U.S. patent application number 14/937512 was filed with the patent office on 2016-03-03 for cu-ai-mn-based alloy rod and sheet exhibiting stable superelasticity, method of producing the same, vibration damping material using the same, and vibration damping structure constructed by using vibration damping material.
This patent application is currently assigned to TOHOKU UNIVERSITY. The applicant listed for this patent is FURUKAWA ELECTRIC CO., LTD., FURUKAWA TECHNO MATERIAL CO., LTD., TOHOKU UNIVERSITY. Invention is credited to Misato FUJII, Kiyohito ISHIDA, Koji ISHIKAWA, Ryosuke KAINUMA, Sumio KISE, Tomoe KUSAMA, Kenji NAKAMIZO, Toshihiro OMORI, Toyonobu TANAKA, Satoshi TESHIGAWARA.
Application Number | 20160060740 14/937512 |
Document ID | / |
Family ID | 51867124 |
Filed Date | 2016-03-03 |
United States Patent
Application |
20160060740 |
Kind Code |
A1 |
OMORI; Toshihiro ; et
al. |
March 3, 2016 |
Cu-AI-Mn-BASED ALLOY ROD AND SHEET EXHIBITING STABLE
SUPERELASTICITY, METHOD OF PRODUCING THE SAME, VIBRATION DAMPING
MATERIAL USING THE SAME, AND VIBRATION DAMPING STRUCTURE
CONSTRUCTED BY USING VIBRATION DAMPING MATERIAL
Abstract
A Cu--Al--Mn-based alloy rod having superelastic characteristics
and having a recrystallized microstructure substantially formed of
a .beta. single phase, wherein, for a longitudinal direction cross
section of the rod, a region, in which a grain size of each of
grains is a radius of the rod or more, is 90% or more of the
longitudinal direction cross section at any location of the rod,
and wherein an average grain size of the grains, in which the grain
size is the radius of the rod or more, is 80% or more of a diameter
of the rod; a Cu--Al--Mn-based alloy sheet; a production method
thereof; a vibration damping material using thereof; a vibration
damping structure constructed by using the vibration damping
material.
Inventors: |
OMORI; Toshihiro;
(Sendai-shi, JP) ; KUSAMA; Tomoe; (Sendai-shi,
JP) ; KAINUMA; Ryosuke; (Sendai-shi, JP) ;
ISHIDA; Kiyohito; (Sendai-shi, JP) ; TANAKA;
Toyonobu; (Hiratsuka-shi, JP) ; KISE; Sumio;
(Hiratsuka-shi, JP) ; NAKAMIZO; Kenji;
(Hiratsuka-shi, JP) ; ISHIKAWA; Koji;
(Hiratsuka-shi, JP) ; FUJII; Misato;
(Hiratsuka-shi, JP) ; TESHIGAWARA; Satoshi;
(Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOHOKU UNIVERSITY
FURUKAWA TECHNO MATERIAL CO., LTD.
FURUKAWA ELECTRIC CO., LTD. |
Sendai-shi
Hiratsuka-shi
Tokyo |
|
JP
JP
JP |
|
|
Assignee: |
TOHOKU UNIVERSITY
Sendai-shi
JP
FURUKAWA ELECTRIC CO., LTD.
Tokyo
JP
FURUKAWA TECHNO MATERIAL CO., LTD.
Hiratsuka-shi
JP
|
Family ID: |
51867124 |
Appl. No.: |
14/937512 |
Filed: |
November 10, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2014/060586 |
Apr 14, 2014 |
|
|
|
14937512 |
|
|
|
|
Current U.S.
Class: |
148/563 ;
148/402 |
Current CPC
Class: |
C22C 9/01 20130101; B22D
21/025 20130101; C22C 9/05 20130101; C22F 1/08 20130101; C22F 1/00
20130101; C22F 1/006 20130101 |
International
Class: |
C22F 1/00 20060101
C22F001/00; B22D 21/02 20060101 B22D021/02; C22F 1/08 20060101
C22F001/08; C22C 9/01 20060101 C22C009/01; C22C 9/05 20060101
C22C009/05 |
Foreign Application Data
Date |
Code |
Application Number |
May 10, 2013 |
JP |
2013-099996 |
Claims
1. A Cu--Al--Mn-based alloy rod having superelastic characteristics
and having a recrystallized microstructure substantially formed of
a .beta. single phase, wherein, for a longitudinal direction cross
section of the rod, a region, in which a grain size of each of
grains is a radius of the rod or more, is 90% or more of the
longitudinal direction cross section at any location of the rod,
and wherein an average grain size of the grains, in which the grain
size is the radius of the rod or more, is 80% or more of a diameter
of the rod.
2. The Cu--Al--Mn-based alloy rod as claimed in claim 1, wherein
the average grain size is the diameter of the rod or more.
3. The Cu--Al--Mn-based alloy rod as claimed in claim 1, wherein
the Cu--Al--Mn-based alloy has a composition containing 3 to 10
mass % of Al; 5 to 20 mass % of Mn; optionally 1 mass % or less of
Ni; and optionally 0.001 to 10 mass % in total of at least one
element selected from the group consisting of Co, Fe, Ti, V, Cr,
Si, Nb, Mo, W, Sn, Mg, P, Be, Sb, Cd, As, Zr, Zn, and Ag, with the
balance being Cu and unavoidable impurities.
4. A method of producing a Cu--Al--Mn-based alloy rod having a
composition containing 3 to 10 mass % of Al, 5 to 20 mass % of Mn,
optionally 1 mass % or less of Ni; and optionally 0.001 to 10 mass
% in total of at least one element selected from the group
consisting of Co, Fe, Ti, V, Cr, Si, Nb, Mo, W, Sn, Mg, P, Be, Sb,
Cd, As, Zr, Zn, and Ag, with the balance being Cu and unavoidable
impurities, comprising through [Step 1] to [Step 3], in this order:
melting and casting an alloy material which gives the composition
[Step 1]; subjecting to hot working [Step 2]; and performing memory
heat treatment [Step 3], wherein, for the memory heat treatment
[Step 3], heating is carried out from a room temperature to a
temperature range to be a .beta. phase [Step 3-1]; heating for
maintaining the heating temperature for 1 to 120 minutes; and then,
cooling [Step 3-2] and heating [Step 3-3] are each repeated once or
more; heating is carried out, in which the cooling [Step 3-2] and
the heating [Step 3-3] are set to a temperature to be an
.alpha.+.beta. phase at a low temperature and are set to a
temperature to be a .beta. phase at a high temperature, and in
which a cooling speed and a temperature-raising speed at the time
of the cooling [Step 3-2] and the heating [Step 3-3] are
respectively set to 0.1 to 100.degree. C./minute; and, after final
heating, heating for quenching from the temperature to be the
.beta. phase [Step 3-4] is carried out.
5. The method of producing a Cu--Al--Mn-based alloy rod as claimed
in claim 4, wherein, after the subjecting to hot working [Step 2],
intermediate annealing that is carried out at 400 to 600.degree. C.
for 1 to 120 minutes [Step 2-1] and cold-working at a working ratio
of 30% or more [Step 2-2] are carried out at least one time each in
this order, and then, the memory heat treatment [Step 3] is carried
out.
6. A vibration damping material being composed of the
Cu--Al--Mn-based alloy rod as claimed in claim 1.
7. A vibration damping structure constructed of the vibration
damping material as claimed in claim 6.
8. A Cu--Al--Mn-based alloy sheet having superelastic
characteristics and having a recrystallized microstructure
substantially formed of a .beta. single phase, wherein, for a cross
section of a sheet thickness direction and a longitudinal direction
of the sheet, a region, in which a grain size of each of grains is
a half of a sheet thickness or more, is 90% or more of the cross
section of the sheet thickness direction and the longitudinal
direction at any location of the sheet, and wherein an average
grain size of the grains, in which the grain size is the half of
the sheet thickness or more, is 80% or more of the sheet
thickness.
9. The Cu--Al--Mn-based alloy sheet as claimed in claim 8, wherein
the average grain size is the sheet thickness or more.
10. The Cu--Al--Mn-based alloy sheet as claimed in claim 8, wherein
the Cu--Al--Mn-based alloy has a composition containing 3 to 10
mass % of Al; 5 to 20 mass % of Mn; optionally 1 mass % or less of
Ni; and optionally 0.001 to 10 mass % in total of at least one
element selected from the group consisting of Co, Fe, Ti, V, Cr,
Si, Nb, Mo, W, Sn, Mg, P, Be, Sb, Cd, As, Zr, Zn, and Ag, with the
balance being Cu and unavoidable impurities.
11. A method of producing a Cu--Al--Mn-based alloy sheet having a
composition containing 3 to 10 mass % of Al, 5 to 20 mass % of Mn,
optionally 1 mass % or less of Ni; and optionally 0.001 to 10 mass
% in total of at least one element selected from the group
consisting of Co, Fe, Ti, V, Cr, Si, Nb, Mo, W, Sn, Mg, P, Be, Sb,
Cd, As, Zr, Zn, and Ag, with the balance being Cu and unavoidable
impurities, comprising through [Step 1] to [Step 3], in this order:
melting and casting an alloy material which gives the composition
[Step 1]; subjecting to hot working [Step 2]; and performing a
memory heat treatment [Step 3], wherein, for the memory heat
treatment [Step 3], heating is carried out from a room temperature
to a temperature range to be a .beta. phase [Step 3-1]; heating for
maintaining the heating temperature for 1 to 120 minutes; and then,
cooling [Step 3-2] and heating [Step 3-3] are each repeated once or
more; heating is carried out, in which the cooling [Step 3-2] and
the heating [Step 3-3] are set to a temperature to be an
.alpha.+.beta. phase at a low temperature and are set to a
temperature to be a .beta. phase at a high temperature, and in
which a cooling speed and a temperature-raising speed at the time
of the cooling [Step 3-2] and the heating [Step 3-3] are
respectively set to 0.1 to 100.degree. C./minute; and, after final
heating, heating for quenching from the temperature to be the
.beta. phase [Step 3-4] is carried out.
12. The method of producing a Cu--Al--Mn-based alloy sheet as
claimed in claim 11, wherein, after the subjecting to the hot
working [Step 2], intermediate annealing that is carried out at 400
to 600.degree. C. for 1 to 120 minutes [Step 2-1] and cold-working
at a working ratio of 30% or more [Step 2-2] are carried out at
least one time each in this order, and then, the memory heat
treatment [Step 3] is carried out.
13. A vibration damping material being composed of the
Cu--Al--Mn-based alloy sheet as claimed in claim 8.
14. A vibration damping structure constructed of the vibration
damping material as claimed in claim 13.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of PCT International
Application No. PCT/JP2014/060586 filed on Apr. 14, 2014, which
claims priority under 35 U.S.C. .sctn.119 (a) to Japanese Patent
Application No. 2013-099996 filed in Japan on May 10, 2013. Each of
the above applications is hereby expressly incorporated by
reference, in its entirety, into the present application.
TECHNICAL FIELD
[0002] The present invention relates to a Cu--Al--Mn-based alloy
rod and sheet exhibiting excellent stable superelastic
characteristics, a method of producing the same, a vibration
damping material, and a vibration damping structure constructed by
using the vibration damping material.
BACKGROUND ART
[0003] Shape memory alloys/superelastic alloys exhibit a remarkable
shape memory effect and superelastic characteristics concomitantly
to reverse transformation of the thermoelastic martensite
transformation, and have excellent functions near the living
environment temperature. Accordingly, these alloys have been put to
practical use in various fields. Representative alloys of the shape
memory alloys/superelastic alloys include TiNi alloys and Cu-based
alloys. Copper-based shape memory alloys/superelastic alloys
(hereinafter, those are simply referred to copper-based alloys)
have characteristics inferior to those of TiNi alloys in terms of
repetition characteristics, corrosion resistance, and the like. On
the other hand, since the cost is inexpensive, there has been a
movement to extend the application range of copper-based alloys.
However, although the copper-based alloys are advantageous in terms
of costs, those alloys are poor in cold workability and low in
superelastic characteristics. For those reasons, despite that a
variety of studies are being conducted, it is the current situation
that practicalization of copper-based alloys has not been
necessarily sufficiently progressed.
[0004] Heretofore, various investigations have been conducted on
copper-based alloys. For example, Cu--Al--Mn-based shape memory
alloys of which a grain size is controlled and which has a .beta.
single phase structure with excellent cold workability have been
reported in Patent Literatures 1 to 3 described below.
CITATION LIST
Patent Literatures
[0005] Patent Literature 1: JP-A-2005-298952 ("JP-A" means
unexamined published Japanese patent application)
Patent Literature 2: JP-A-2001-20026
Patent Literature 3: International Publication WO 2011/152009
A1
SUMMARY OF INVENTION
Technical Problem
[0006] In Patent Literature 1, Cu--Al--Mn--Ni alloys are controlled
to be ultrafine crystalline grain microstructure of 10 .mu.m or
less. Further, Cu--Al--Mn--Ni alloys described in Patent Literature
1 contain Ni necessarily, and Ni content up to 10 mass % is allowed
to be contained. By including Ni, even though crystals are refined,
a vibration damping performance is exhibited. Therefore, the
crystalline orientation of a .beta. single phase (austenitic single
phase) is easily controlled. However, a quenching property is
reduced. Herein, the quenching property (or quench-hardening
sensitivity) indicates the relationship between the cooling speed
in the quenching and the stability of microstructure in the
quenching just before the quenching. In detail, when the cooling
speed is slow at the time of the quenching, the phenomenon, in
which an a phase is precipitated, and thus, superelastic
characteristic is poor, is said that the quenching property is
sensitive. It is confirmed that since an a phase is started to be
precipitated at higher temperature in the Ni-containing copper
alloys, a wire diameter becomes thick, and thus, the cooling time
period becomes slightly longer, thereby making a quenching property
poor, and thereby, satisfactory superelastic characteristic may not
be obtained.
[0007] In copper-based alloys described in Patent Literatures 2 and
3, the shape memory characteristics and superelastic
characteristics to be manifested by those alloys are less stable,
and, from the viewpoint that these characteristics are not stable,
the copper-based alloys are at a level having a room for further
improvement. In Patent Literature 2, in order to improve the shape
memory characteristics and superelastic characteristics of the
copper-based alloys, there have been proposed that the crystalline
orientations of a .beta. single phase are controlled; in the case
of a rod, the average grain size is to be the half of the rod
diameter or more or in the case of a sheet, it is to be the sheet
thickness or more; and also, the region having the grain diameter
is to be 30% or more of the total length of the rod or the total
region of the sheet. Further, in Patent Literature 3, in order to
improve the shape memory characteristics of the copper-based alloys
and also to make the copper-based alloys to have a large cross
sectional size that can be applied for a structure, there has been
proposed a large crystalline microstructure, in which the maximum
grain size is larger than 8 mm. However, with the methods disclosed
in Patent Literatures 2 and 3, the grain size distribution of the
grains having a predetermined large grain diameter in the
Cu--Al--Mn-based alloys is still controlled insufficiently, and
shape memory characteristics and superelastic characteristics are
still yet insufficiently stable.
[0008] As such, in regard to those shape memory copper-besed alloys
that have been hitherto obtained, the investigation on the effect
of the control of the grain size distribution of grains having a
predetermined large grain size on the superelastic characteristics
is insufficient, and thus, the stability and reproducibility of
superelastic characteristic are still insufficient.
[0009] The present invention is implemented for providing a
Cu--Al--Mn-based alloy rod and sheet which stably exhibits
satisfactory superelastic characteristics; for providing a method
of producing the same; for providing a vibration damping material
using the same; and for providing a vibration damping structure
constructed by using the vibration damping material.
Solution to Problem
[0010] The inventors of the present invention conducted a thorough
investigation in order to solve the problems of the related art as
described above. As a result, the inventors found that, in
Cu--Al--Mn-based copper alloys having a coarse crystalline grain
microstructure that is close to so-called bamboo microstructure
(which is a metal microstructure having a crystalline structure, in
which a grain boundary is situated like bamboo joints), with most
of the regions thereof being configured by large grains in a
predetermined size or more, and the area ratio of the large grains
in the predetermined size or more and the average grain size of the
large grains in the predetermined size or more being controlled in
the proper range, respectively, Cu--Al--Mn-based alloys which
stably exhibit satisfactory superelastic characteristics can be
obtained. The inventors also found that the controlling of the
grain size distribution and average grain size could be obtained by
performing the memory heat treatment at the memory heating
conditions by a specific slow-lowering speed or raising speed in
temperature. The present invention was completed based on these
findings.
[0011] That is, the present invention provides the following
means:
(1) A Cu--Al--Mn-based alloy rod having superelastic
characteristics and having a recrystallized microstructure
substantially formed of a .beta. single phase,
[0012] wherein, for a longitudinal direction cross section of the
rod, a region, in which a grain size of each of grains is a radius
of the rod or more, is 90% or more of the longitudinal direction
cross section at any location of the rod, and wherein an average
grain size of the grains, in which the grain size is the radius of
the rod or more, is 80% or more of a diameter of the rod.
(2) The Cu--Al--Mn-based alloy rod described in the item (1),
wherein the average grain size is the diameter of the rod or more.
(3) The Cu--Al--Mn-based alloy rod described in the item (1) or
(2), wherein the Cu--Al--Mn-based alloy has a composition
containing 3 to 10 mass % of Al; 5 to 20 mass % of Mn; optionally 1
mass % or less of Ni; and optionally 0.001 to 10 mass % in total of
at least one element selected from the group consisting of Co, Fe,
Ti, V, Cr, Si, Nb, Mo, W, Sn, Mg, P, Be, Sb, Cd, As, Zr, Zn, and
Ag, with the balance being Cu and unavoidable impurities. (4) A
method of producing a Cu--Al--Mn-based alloy rod having a
composition containing 3 to 10 mass % of Al, 5 to 20 mass % of Mn,
optionally 1 mass % or less of Ni; and optionally 0.001 to 10 mass
% in total of at least one element selected from the group
consisting of Co, Fe, Ti, V, Cr, Si, Nb, Mo, W, Sn, Mg, P, Be, Sb,
Cd, As, Zr, Zn, and Ag, with the balance being Cu and unavoidable
impurities, comprising through [Step 1] to [Step 3], in this
order:
[0013] melting and casting [Step 1] an alloy material which gives
the composition;
[0014] subjecting to hot working [Step 2]; and
[0015] performing memory heat treatment [Step 3],
[0016] wherein, for the memory heat treatment [Step 3], heating
[Step 3-1] is carried out from a room temperature to a temperature
range to be a .beta. phase; heating for maintaining the heating
temperature for 1 to 120 minutes; and then, cooling [Step 3-2] and
heating [Step 3-3] are each repeated once or more; heating is
carried out, in which the cooling [Step 3-2] and the heating [Step
3-3] are set to a temperature to be an .alpha.+.beta. phase at a
low temperature and are set to a temperature to be a .beta. phase
at a high temperature, and in which a cooling speed and a
temperature-raising speed at the time of the cooling [Step 3-2] and
the heating [Step 3-3] are respectively set to 0.1 to 100.degree.
C./minute; and, after final heating, heating for quenching [Step
3-4] from the temperature to be the .beta. phase is carried
out.
(5) The method of producing a Cu--Al--Mn-based alloy rod described
in the item (4), wherein, after the hot working [Step 2],
intermediate annealing [Step 2-1] that is carried out at 400 to
600.degree. C. for 1 to 120 minutes and cold-working [Step 2-2] at
a working ratio of 30% or more are carried out at least one time
each in this order, and then, the memory heat treatment [Step 3] is
carried out. (6) A vibration damping material being composed by
using the Cu--Al--Mn-based alloy rod described in any one of the
items (1) to (3). (7) A Cu--Al--Mn-based alloy sheet having
superelastic characteristics and having a recrystallized
microstructure substantially formed of a .beta. single phase,
[0017] wherein, for a cross section of a sheet thickness direction
and a longitudinal direction of the sheet, a region, in which a
grain size of each of grains is a half of a sheet thickness or
more, is 90% or more of the cross section of the sheet thickness
direction and the longitudinal direction at any location of the
sheet, and wherein an average grain size of the grains, in which
the grain size is the half of the sheet thickness or more, is 80%
or more of the sheet thickness.
(8) The Cu--Al--Mn-based alloy sheet described in the item (7),
wherein the average grain size is the sheet thickness or more. (9)
The Cu--Al--Mn-based alloy sheet described in the item (7) or (8),
wherein the Cu--Al--Mn-based alloy has a composition containing 3
to 10 mass % of Al; 5 to 20 mass % of Mn; optionally 1 mass % or
less of Ni; and optionally 0.001 to 10 mass % in total of at least
one element selected from the group consisting of Co, Fe, Ti, V,
Cr, Si, Nb, Mo, W, Sn, Mg, P, Be, Sb, Cd, As, Zr, Zn, and Ag, with
the balance being Cu and unavoidable impurities. (10) A method of
producing a Cu--Al--Mn-based alloy sheet having a composition
containing 3 to 10 mass % of Al, 5 to 20 mass % of Mn, optionally 1
mass % or less of Ni; and optionally 0.001 to 10 mass % in total of
at least one element selected from the group consisting of Co, Fe,
Ti, V, Cr, Si, Nb, Mo, W, Sn, Mg, P, Be, Sb, Cd, As, Zr, Zn, and
Ag, with the balance being Cu and unavoidable impurities,
comprising through [Step 1] to [Step 3], in this order:
[0018] melting and casting [Step 1] an alloy material which gives
the composition;
[0019] subjecting to hot working [Step 2]; and
[0020] performing a memory heat treatment [Step 3],
[0021] wherein, for the memory heat treatment [Step 3], heating
[Step 3-1] is carried out from a room temperature to a temperature
range to be a .beta. phase; heating for maintaining the heating
temperature for 1 to 120 minutes; and then, cooling [Step 3-2] and
heating [Step 3-3] are each repeated once or more; heating is
carried out, in which the cooling [Step 3-2] and the heating [Step
3-3] are set to a temperature to be an .alpha.+.beta. phase at a
low temperature and are set to a temperature to be a .beta. phase
at a high temperature, and in which a cooling speed and a
temperature-raising speed at the time of the cooling [Step 3-2] and
the heating [Step 3-3] are respectively set to 0.1 to 100.degree.
C./minute; and, after final heating, heating for quenching [Step
3-4] from the temperature to be the .beta. phase is carried
out.
(11) The method of producing a Cu--Al--Mn-based alloy sheet
described in the item (10), wherein, after the hot working [Step
2], intermediate annealing [Step 2-1] that is carried out at 400 to
600.degree. C. for 1 to 120 minutes and cold-working [Step 2-2] at
a working ratio of 30% or more are carried out at least one time
each in this order, and then, the memory heat treatment [Step 3] is
carried out. (12) A vibration damping material being composed by
using the Cu--Al--Mn-based alloy sheet described in any one of the
items (7) to (9). (13) A vibration damping structure constructed by
using the vibration damping material described in the items (6) or
(12).
[0022] The Cu-Ai-Mn-based alloy rod and sheet of the present
invention is preferably such that, as the superelastic
characteristics, the residual strain after 6% strain loading is
1.0% or less, and the elongation at breakage is 6% or more.
[0023] Herein, the expression `having superelastic characteristics`
or `superelastic characteristics are excellent`, the strain
remaining when a predetermined loading strain or loading stress is
applied thereto and then the load is eliminated, is referred to as
residual strain, and it is meant that this residual strain is
small. It is more desirable as this residual strain is smaller. In
the present invention, it is meant that the residual strain after
6% deformation is generally 1.0% or less, preferably 0.5% or less,
and more preferably 0.2% or less.
[0024] Also, the expression `having a recrystallized microstructure
substantially formed from a .beta. single phase` means that the
proportion occupied by the .beta. phase in the recrystallization
structure is generally 90% or more, and preferably 95% or more.
Advantageous Effects of Invention
[0025] The Cu--Al--Mn-based superelastic alloy rod and sheet of the
present invention can be used in various applications where
superelastic characteristic are required, and applications are
expected, for example, in antennas of mobile phones, spectacle
frames, as well as orthodontic wires, guide wires, stents,
correcting tools for ingrown nails, and orthoses for hallux valgus,
as medical products. Further, the Cu--Al--Mn-based superelastic
alloy rod and sheet of the present invention is suitable as a
vibration damping material, such as a bus bar, due to its excellent
superelastic characteristics. Further, a vibration damping
structure may be constructed by using such a vibration damping
material.
[0026] Other and further features and advantages of the invention
will appear more fully from the following description,
appropriately referring to the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0027] FIG. 1 is a schematic diagram illustrating a method for
evaluating a grain size.
[0028] FIG. 2-1 illustrates an example of the process chart of a
working and heat treatment. In this example, no intermediate
annealing [Step 2-1] or cold-working [Step 2-2] are conducted.
[0029] FIG. 2-2 illustrates another example of the process chart of
the working and heat treatment. In this example, the intermediate
annealing [Step 2-1] and cold-working [Step 2-2] after a hot
working [Step 2] are repeatedly carried out at least one time in
this order, and then, a memory heat treatment [Step 3] is carried
out.
[0030] FIG. 3a is a stress-strain curve (S-S curve) illustrating
residual strain as superelastic characteristics in the rod (Example
1) of Examples according to this invention, obtained by the
following Examples.
[0031] FIG. 3b is a stress-strain curve (S-S curve) illustrating
residual strain as superelastic characteristics in the rod
(Comparative Example 2) of Comparative Examples, obtained by the
following Examples.
[0032] FIG. 4 is a phase diagram illustrating Cu--Al-10 atom % Mn
alloys.
MODE FOR CARRYING OUT THE INVENTION
[0033] For the Cu--Al--Mn-based alloy rod and sheet of the present
invention, the cooling and heating in the memory heat treatment
(also called a shape memory heat treatment) before the quenching
are carried out at the predetermined slow temperature lowering and
slow temperature raising, respectively, and thus, the grains
thereof are sufficiently grown to the predetermined large size, and
also, the grain size distribution thereof can be properly
controlled. As a result, satisfactory superelastic characteristic
can be stably exhibited.
<Definitions of Grain Size and Grain Size Distribution and
Controls Thereof>
[0034] In the Cu--Al--Mn-based copper alloys constituting the rod
and sheet of the present invention, a small amount of the grains
having a small grain size may be present, but the most grains have
a large grain size.
[0035] In other words, in the case of a rod, in the longitudinal
direction cross section of the rod, the region, in which the grain
size of the respective grains is the radius of the rod or more, is
90% or more of the longitudinal direction cross section at any
locations of the rod, and the average grain size of the grains, in
which the grain size is the radius of the rod or more, is 80% or
more of the diameter of the rod. It is preferable that the average
grain size is the diameter of the rod or more.
[0036] On the other hand, in the case of a sheet, in the cross
section of the longitudinal direction and the sheet thickness
direction of the sheet, the region, in which the grain size of the
respective grains is the half of the sheet thickness or more, is
90% or more of the cross section of the sheet thickness direction
and the longitudinal direction at any locations of the sheet, and
the average grain size of the grains, in which the grain size is
the half of the sheet thickness or more, is 80% or more of the
sheet thickness. It is preferable that the average grain size is
the sheet thickness or more.
[0037] Herein, when the present ratio of the large grains in the
predetermined range is expressed, it is defined as the area ratio,
in which the grains in the predetermined size or more occupy the
rod or sheet. Further, by defining the average grain size of the
grains in the predetermined size or more, the structural
characteristics are defined.
[0038] Unlike the rod, the shape of the sheet is not a round-shaped
cross section, and thus, has a low symmetric property. Thus, the
standard of the grain size is a sheet thickness, not a sheet width.
The reason is based on the fact that, after the grains penetrate
through the sheet thickness or sheet width, the driving force of
the growth of the grain boundary interface by the grains is
lowered, and thus, the grains are increased in their sizes, but it
is difficult to penetrate through the sheet width as well as the
sheet thickness.
[0039] In the Cu--Al--Mn-based alloy rod and sheet of the present
invention, the average grain size of the matrix (the base material)
is to be the proper size. This is because in the Cu--Al--Mn-based
alloys, when the average grain size is too small, the restriction
between the grains is generated from the surrounding grains at the
time of being deformed, and thus, the resistance to the deformation
becomes larger, thereby deteriorating the superelastic
characteristics. In the present invention, the upper limit of the
average grain size is not particularly limited, and for example,
there are particularly no problems as long as the upper limit is
practically obtained (for example, about 150 mm). Further, even
when the grains having a large grain size are unevenly distributed,
and thus, the non-uniform distribution is generated, the
deformation of the copper alloy rod and sheet of the present
invention becomes unevenness, which is undesirable. Therefore, in
the present invention, as described above, "the region, in which
the grain size of the respective grains is the radius of the rod or
more, is 90% or more of the longitudinal direction cross section at
any locations of the rod" or "the region, in which the grain size
of the respective grains is the half of the sheet thickness or
more, is 90% or more of the cross section of the sheet thickness
direction and the longitudinal direction at any locations of the
sheet," and the grain size distribution is defined by the
respective area ratio.
[0040] In the present invention, for the wire (rod) and sheet, by
controlling the grain size distribution and average grain size as
described above, it is possible to stabilize the superelastic
characteristics. In the present invention, because of the
difference of the shapes of the rod or sheet products, the rod and
sheet are defined as different product inventions. However, in
terms of the wrought alloy of Cu--Al--Mn-based superelastic alloys,
the rod and sheet are different each other in that the grain size
is defined to the diameter of the rod or the grain size is defined
to the sheet thickness, but the special technical features of both
inventions are common, and thus, both the inventions have the
common technical significance (features). Further, in the
inventions of the method of producing a rod and the method of
producing a sheet, the same can be said to the product inventions.
Therefore, it can be interpreted that both the inventions have the
common technical significance.
[0041] For the Cu--Al--Mn-based alloy rod and sheet of the present
invention, the grains in the predetermined grain size distribution
and the predetermined size or more have the average grain size in
the predetermined size or more. This is because the effect of the
grains each having the size that is considered less than the
predetermined size may be ignored, since the grain size of the
grains each having the size that is the predetermined size or more
is defined, the amount of the grains each having the size that is
less than the predetermined size is conspicuously low as compared
to the grains each having the size that is the predetermined size
or more, and the effect to the superelastic characteristics is
small.
[0042] Further, the Cu--Al--Mn-based alloy rod and sheet of the
present invention is substantially composed of a .beta. single
phase. Herein, the expression `being substantially composed of a
.beta. single phase` means that the existence ratio of a phase
other than the .beta. phase, for example, an a phase, is generally
10% or less, and preferably 5% or less.
[0043] For example, a Cu-8.1 mass % Al-11.1 mass % Mn alloy is a
.beta. (BCC) single phase at 900.degree. C., but is the two phases
of an a (FCC) phase+the .beta. phase at 700.degree. C. or less.
<Method of Producing Cu--Al--Mn-Based Superelastic Alloy Rod and
Sheet>
[0044] In regard to the Cu--Al--Mn-based superelastic copper-based
alloy rod and sheet of the present invention, a production process
such as described below may be mentioned, in connection with the
production conditions for obtaining the superelastic alloy rod and
sheet which stably exhibit satisfactory superelastic
characteristics such as described above. Further, a preferred
example of the production process is illustrated in FIGS. 2-1 and
2-2. The treatment temperatures and treatment times (maintaining
time periods) in the heat treatments illustrated in the figures,
and the working ratio in the cold-working are representatively
represented as the values utilized in the Examples, but the present
invention is not limited thereto.
[0045] In the entire production process, particularly by
controlling both the temperature lowering speed in the memory heat
treatment and the temperature raising speed after the cooling each
in the predetermined slow ranges, the grains can be sufficiently
grown to the predetermined large sizes, and also, by controlling
properly the grain size distribution thereof, a Cu--Al--Mn-based
alloy is obtained, which stably exhibits satisfactory superelastic
characteristics.
[0046] Furthermore, the intermediate annealing at 400 to
600.degree. C. for 1 to 120 minutes and the cold-working, in which
the working ratio of the cold-rolling or cold-drawing is in the
range of 30% or more, may be repeatedly performed at least each one
time after the hot working and before the memory heat treatment.
Alternatively, after the hot working, the intermediate annealing is
only performed at 400 to 600.degree. C. for 1 to 120 minutes, and
after the intermediate annealing, the memory heat treatment may be
performed without performing the cold working.
[0047] Herein, for the memory heat treatment, the heating may be
performed to raise the temperature to the temperature range of the
transformation temperature or more in the .beta. phase, in which
the .alpha.+.beta. phase is first changed to the .beta. phase, and
such a heating temperature is maintained for 1 to 120 minutes. At
that time, the heating to the temperature range of the
transformation temperature or more, in which the initial
.alpha.+.beta. phase is changed into the .beta. phase at the time
of memory heat treatment, is performed from a room temperature
after cooling the temperature to a room temperature in general.
However, alternatively, the heating may be performed, just after
the hot working without cooling the temperate to the room temperate
after the hot working, or the heating may be performed, in the
cooling process after the hot working. Herein, the transformation
temperature from the .alpha.+.beta. phase to the .beta. phase is
the boundary temperature between the .alpha.+.beta. phase and the
.beta. phase in the phase diagram as illustrated in FIG. 4. Such a
temperature is determined, for example, by measuring the caloric
change at the time of heating the materials from a low temperature
to a high temperature by a differential scanning calorimetry (DSC)
measuring device, and the like. Then, the heat treatment cycle, in
which the temperature is lowered by the cooling to be the
temperature range that is less than the transformation temperature,
and then, immediately, the temperature is raised by the heating to
be the temperature range that is to be the .beta. phase, is
repeated at least one time, such that the .beta. phase becomes the
.alpha.+.beta. phase. Further, in order to make the microstructure
to be a .beta. single phase and make the grains grow to satisfy the
definition of the present invention, the heating temperature is
preferably higher than the transformation temperature by 50.degree.
C. or more. Further, in the case where the temperature is lowered
by the cooling to be the temperature range that is less than the
transformation temperature for the .alpha.+.beta. phase, the
temperature is preferably lower than the transformation temperature
by 50.degree. C. or less. Herein, the temperature lowering speed at
the time of cooling to less than the transformation temperature
(the cooling of [Step 3-2]), and the temperature raising speed at
the time of heating to the transformation temperature or more (the
heating of [Step 3-3]) are preferably slow as described below.
Then, finally, the solid-solution treatment including the quenching
(the quenching of [Step 3-4]) is performed.
[0048] Herein, for the memory heat treatment, the temperature
lowering speed (the temperature lowering speed at the cooling of
[Step 3-2]) and the temperature raising speed (the temperature
raising speed at the heating of [Step 3-3]) are both set to be slow
(in this specification, called a temperature slow-lowering speed
and a temperature slow-raising speed). The temperature lowering
speed at the time of the temperature slow-lowering and the
temperature raising speed at the time of the temperature
slow-raising each are generally 0.1 to 100.degree. C./minutes,
preferably 0.1 to 10.degree. C./minutes, more preferably 0.1 to
3.degree. C./minutes, and particularly preferably 0.2 to 1.degree.
C./minutes. Further, in the memory heat treatment, in order for the
solid-solution treatment after the heat treatment (the temperature
raising to the .beta. single phase (in the figures, abbreviated as
"6", and the same is applied to as above).fwdarw.the temperature
lowering to the .alpha.+.beta. phase (.alpha.+.beta.).fwdarw.the
temperature raising to the .beta. single phase (.beta.).fwdarw.),
the quenching is performed. For example, such a quenching may be
performed by the water-cooling, in which the Cu--Al--Mn-based
alloys subjected to the heat treatment are put into the cooling
water.
[0049] Preferably, the production process such as follows may be
mentioned.
[0050] As an example, after melting and casting [Step 1] of an
alloy raw material to give the following predetermined composition
and hot working [Step 2] of hot rolling or hot forging, the memory
heat treatment [Step 3] is carried out in this order. Then, after
the memory heat treatment [Step 3], aging-heating [Step 4] may be
carried out.
[0051] As another example, the melting and casting [Step 1] and the
hot working [Step 2] are carried out; then, the intermediate
annealing [Step 2-1] and cold-working [Step 2-2] are carried out
each at least one time; and then, the memory heat treatment [Step
3] is carried out, in this order. After the memory heat treatment
[Step 3], the aging-heating [4] may be carried out.
[0052] Further, as still another example, the melting and casting
[Step 1] and the hot working [Step 2] are carried out; then, the
intermediate annealing [Step 2-1] is carried out; and then, the
memory heat treatment [Step 3] is carried out, in this order. After
the memory heat treatment [Step 3], the aging-heating [4] may be
carried out.
[0053] The memory heat treatment [Step 3] contains the steps of:
heating by the temperature range to be the .beta. phase;
maintaining such a heating temperature for 1 to 120 minutes;
temperature-raising treatment [Step 3-1] for making such a heating
temperature to be the .beta. single phase temperature range, for
example, 700 to 950.degree. C. (preferably, 800 to 920.degree. C.);
temperature-lowering treatment [Step 3-2] for cooling the
temperature from such a heating temperature to the temperature
range to be the .alpha.+.beta. phase at the temperature-lowering
speed, for example, 300 to 700.degree. C. (preferably, 400 to
550.degree. C.); temperature-raising treatment [Step 3-3] for
heating the temperature from such a temperature-lowering
temperature to the temperature range to be the .beta. phase at the
temperature-raising speed, and maintaining such a heating
temperature for certain time periods (preferably, 1 to 120
minutes); and then quenching [Step 3-4], for example, by cold
water. For the temperature-raising treatment [Step 3-1], the
temperature-raising speed is not particularly limited, but the
temperature-raising speed in the temperature-raising treatment
[Step 3-3] may be used or a faster speed than the above speed may
be used. When the heating maintaining time at the .beta. phase in
the temperature-raising treatment [Step 3-1] is less than 1 minute,
the heating is insufficient, and when it exceeds 120 minutes, the
heating is already sufficient, and even if maintaining over the
time, there are no newly improvement and also a waste of thermal
energy. Therefore, the heating maintaining time at the .beta. phase
in the temperature-raising treatment [Step 3-1] is set to be 1 to
120 minutes. Herein, the heat treatment cycle including the
temperature-lowering treatment [Step 3-2] and the
temperature-raising treatment [Step 3-3] may be repeatedly carried
out each at least one time as described above. The cooling speed at
the time of quenching [Step 3-4] is generally 30.degree. C./second
or more, preferably 100.degree. C./second or more, and more
preferably, 1,000.degree. C./second or more.
[0054] In the present invention, the intermediate annealing [Step
2-1] and the cold-working [Step 2-2] may be carried out or may not
be carried out. Even if any intermediate annealing [Step 2-1] and
cold-working [Step 2-2] are to be carried out, they may be carried
out each once in this order or may be repeatedly carried out once
two times in this order.
[0055] Alternatively, the cold-working [Step 2-2] may not be
carried out, but the intermediate annealing [Step 2-1] may be only
carried out.
[0056] After the memory heat treatment [Step 3], the aging-heating
[Step 4] at 80 to 250.degree. C. for 5 to 60 minutes may be carried
out. Any aging-heating [Step 4] may be preferably carried out. When
the aging temperature is too low, the 6 phase is unstable, and when
putting at a room temperature, the martensite transformation
temperature may be changed. On the other hand, when the aging
temperature is too high, the precipitation of a phase may be
carried out, and thus, there may be a trend that the shape memory
characteristic and superelastic characteristics are conspicuously
lowered.
[0057] The intermediate annealing [Step 2-1] and cold-rolling or
cold-wire-drawing [Step 2-2] may be repeatedly carried out at a
plurality of times, and thereby, grain growth may be more stable.
The repetition number of intermediate annealings [Step 2-1] and
cold-rollings or cold-wire-drawings [Step 2-2] is preferably 2
times or more, and more preferably 3 times or more. This repetition
number is not particularly limited in terms of the upper limit, but
generally 10 times or less, and preferably 7 times or less. As the
repetition number of intermediate annealings [Step 2-1] and
cold-rollings or cold-wire-drawings [Step 2-2] is high, the driving
force of the grain growth becomes high, and thus, it is easy to
uniformly make the size of the grain coarse.
[0058] Preferred conditions for the steps are as follows.
[0059] The intermediate annealing [Step 2-1] is preferably carried
out at 400 to 600.degree. C. for 1 minute to 120 minutes. It is
preferable that this intermediate annealing temperature be set to a
lower temperature within this range; and the intermediate annealing
temperature is more preferably set to 400 to 550.degree. C.,
further preferably 400 to 500.degree. C., and particularly
preferably 400.degree. C. to 450.degree. C. The annealing time is
more preferably 30 minute to 120 minutes, and even if the influence
of the sample size is considered, an annealing time of 60 minutes
is sufficient for a round rod with diameter .phi.20 mm.
[0060] For the cold-rolling or cold-wire-drawing [Step 2-2], it is
preferable to carry out the step at a working ratio of 30% or
higher, more preferably 40% or higher, further preferably from 45
to 75%, and particularly preferably from 45 to 60%. Herein, the
working ratio is a value defined by formula:
Working ratio(%)={(A.sub.1-A.sub.2)/A.sub.1}.times.100
wherein A.sub.1 represents the cross-sectional area (mm.sup.2)
obtained before cold-rolling or cold-wire-drawing; and A.sub.2
represents the cross-sectional area (mm.sup.2) obtained after
cold-rolling or cold-wire-drawing.
<Composition of Cu--Al--Mn-Based Superelastic Alloy Rod and
Sheet>
[0061] The Cu--Al--Mn-based alloy rod and sheet of the present
invention is formed of a copper alloy which has the .beta. single
phase at a high temperature, and a two-phase microstructure of
.beta.+.alpha. at a low temperature, and is formed of a
copper-based alloy containing at least Al and Mn. The
Cu--Al--Mn-based alloy that forms the rod and sheet of the present
invention has a composition containing 3 to 10 mass % of Al and 5
to 20 mass % of Mn, with the balance being Cu and unavoidable
impurities. If the content of elemental Al is too small, the .beta.
single phase cannot be formed, and if the content is too large, the
resultant alloy becomes very brittle. The content of elemental Al
may vary depending onto the content of elemental Mn, but a
preferred content of elemental Al is 6 to 10 mass %. When the alloy
contains elemental Mn, the range of existence of the .beta. phase
extends to a lower Al-content side, and cold workability is
markedly enhanced, for thereby making the form-working readily. If
the amount of addition of elemental Mn is too small, satisfactory
workability is not obtained, and the region of the .beta. single
phase cannot be formed. Also, if the amount of addition of
elemental Mn is too large, sufficient shape recovery
characteristics are not obtained. A preferred content of Mn is 8 to
12 mass %. The Cu--Al--Mn alloy having the above-described
composition has high hot workability and cold workability, and
enables to obtain a working ratio of 20 to 90% or higher in cold
working. Thus, the alloy can be readily worked by forming into
sheets and wires (rods), as well as fine wires, foils, pipes and
the like that have been conventionally difficult to produce.
[0062] In addition to the essential alloying elements described
above, the Cu--Al--Mn-based alloy that forms the rod and sheet of
the present invention can further contain, as an optionally adding
alloying element(s), at least one selected from the group
consisting of Co, Fe, Ti, V, Cr, Si, Nb, Mo, W, Sn, Mg, P, Be, Sb,
Cd, As, Zr, Zn, and Ag. These elements enhance the physical
strength of the resultant Cu--Al--Mn-based alloy, while maintaining
cold workability. The content in total of these elements is
preferably 0.001 to 10 mass %, and particularly preferably 0.001 to
5 mass %. If the content of these elements is too large, the
martensite transformation temperature is lowered, and the .beta.
single phase microstructure becomes unstable. Regarding these
optionally adding alloying elements, use can be made of the
aforementioned elements that are generally used by being contained
into copper-base alloys, for example, for the purpose of
strengthening of copper alloys.
[0063] Co, Fe and Sn are elements that are effective for
strengthening of the matrix microstructure. Co makes the grains
coarse by forming CoAl; however, Co in an excess amount causes
lowering of toughness of the alloy. A preferred content of Co is
0.001 to 2 mass %. A preferred content of Fe is 0.001 to 3 mass %.
A preferred content of Sn is 0.001 to 1 mass %.
[0064] Ti is bonded to N and O, which are inhibitory elements, and
forms oxynitride. A preferred content of Ti is 0.001 to 2 mass
%.
[0065] V, Nb, Mo and Zr have an effect of enhancing hardness, and
enhance abrasion resistance. Further, since these elements are
hardly solid-solubilized into the matrix, the elements precipitate
as the .beta. phase (bcc crystals), for thereby enhancing the
physical strength. Preferred contents of V, Nb, Mo and Zr are
respectively 0.001 to 1 mass %.
[0066] Cr is an element effective for retaining abrasion resistance
and corrosion resistance. A preferred content of Cr is 0.001 to 2
mass %.
[0067] Si has an effect of enhancing corrosion resistance. A
preferred content of Si is 0.001 to 2 mass %.
[0068] W is hardly solid-solubilized into the matrix, and thus has
an effect of precipitation strengthening. A preferred content of W
is 0.001 to 1 mass %.
[0069] Mg eliminates N and O, which are inhibitory elements, fixes
S that is an inhibitory element as sulfide, and has an effect of
enhancing hot workability or toughness. Addition of a large amount
of Mg brings about grain boundary segregation, and causes
embrittlement. A preferred content of Mg is 0.001 to 0.5 mass
%.
[0070] P acts as a de-oxidation agent, and has an effect of
enhancing toughness. A preferred content of P is 0.01 to 0.5 mass
%.
[0071] Be, Sb, Cd, and As have an effect of strengthening the
matrix microstructure. Preferred contents of Be, Sb, Cd and As are
respectively 0.001 to 1 mass %.
[0072] Zn has an effect of raising the shape memory treatment
temperature. A preferred content of Zn is 0.001 to 5 mass %.
[0073] Ag has an effect of enhancing cold workability. A preferred
content of Ag is 0.001 to 2 mass %.
[0074] The superelastic Cu--Al--Mn-based alloy that forms the rod
and sheet of the present invention preferably has a Ni content of 1
mass % or less, and more preferably 0.15 mass % or less, and it is
particularly preferable that the alloy does not contain Ni. It is
because if the alloy contains Ni in a large amount, but the
quench-hardening property previously explained is deteriorated.
<Physical Properties>
[0075] The superelastic Cu--Al--Mn-based alloy rod and sheet of the
present invention has the following physical properties.
[0076] Regarding the superelastic characteristics, the residual
strain after 6% deformation is generally 1.0% or less, preferably
0.5% or less, and more preferably 0.2% or less.
[0077] The elongation (elongation at breakage) is generally 6% or
more, preferably 8% or more, and more preferably 10% or more.
[0078] Further, the residual strain as the superelastic
characteristics and the elongation have no unevenness in the
performance, even if specimens are cut out from at any sites from a
same alloy and analyzed. Herein, the expression `having unevenness`
means that, in regard to the residual strain and elongation, for
example, when three specimens are cut out from a same alloy and
analyzed, one or more specimens have a residual strain value of
more than 1.0%, or have an elongation value of less than 6%.
<Size of Rod and Sheet>
[0079] There are also no particular limitations on the sizes of the
Cu--Al--Mn-based alloy rod and sheet of the present invention, and,
for example, in the case of the rod, the diameter thereof is
generally 8 mm or more, and for example, 8 mm to 50 mm may also be
employed. The diameter of the rod may be the size of 8 mm to 16 mm
depending on the use thereof. Further, the sheet may have the
thickness of generally 1 mm or more, and for example, 1 mm to 15
mm.
[0080] Further, the rod of the present invention may have the shape
of a tube having a tube wall and a hollow shape.
<Vibration Damping Material>
[0081] The vibration damping material of the present invention is
constituted of the rod or sheet. Examples of the vibration damping
material are not particularly limited, but for example, may include
brace, fastener, anchor bolt, and the like.
<Vibration Damping Structure>
[0082] The vibration damping structure of the present invention is
constructed of the vibration damping material. Examples of the
vibration damping structure are not particularly limited, but any
kinds of the structures may be used as long as the structures are
constructed of using the above-described brace, fastener, anchor
bolt, and the like.
EXAMPLES
[0083] The present invention will be described in more detail based
on examples given below, but the invention is not meant to be
limited by these.
Example 1
[0084] Samples (specimen) of rods (wires) were produced under the
following conditions.
[0085] As the copper alloys that give the compositions as indicated
in Table 1-1 and Table 1-2, pure copper, pure Mn, pure Al, and
materials of other optionally adding alloying elements were
subjected respectively to melting in a high-frequency induction
furnace. The copper alloys thus melted were cooled, to obtain
ingots with diameter of 80 mm.times.length of 300 mm. The ingots
thus obtained were subjected to hot forging at 800.degree. C., to
obtain round rods with diameter 20 mm.
[0086] The round rods were again subjected to (1) hot forging or
(2) cold-wire-drawing, if necessary, to obtain the rods having the
diameters as indicated in Table 2-1 and Table 2-2 with the
conditions as follows.
[0087] That is, according to the respective working and heat
treatment process as illustrated in FIG. 2-1 or FIG. 2-2, the
working and heat treatment were carried out at the conditions
listed in Table 2-1 and Table 2-2. In detail, after the hot working
[Step 1], the intermediate annealing [Step 2-1] and the
cold-wire-drawing [Step 2-2] were not carried out, and the memory
heat treatment [Step 3] was carried out (Examples 1 to 23, Example
28, respective Comparative Examples) (Process of FIG. 2-1), or
after the hot working [Step 1], the intermediate annealing [Step
2-1] at 500.degree. C. for 1 hour and then the cold-wire-drawing
[Step 2-2] were carried out once each or were repeatedly carried
out at a plurality of times (Examples 24 to 27) (Process of FIG.
2-2). For all the cases subjected to any kinds of those processes,
then, the rods in Examples and Comparative Examples, which have the
diameters listed in Table 2-1 and Table 2-2, were prepared by:
temperature-raising at the temperature-raising speed of 30.degree.
C./minutes to be 900.degree. C. (the temperature to the .beta.
single phase); maintaining this temperature for 5 minutes;
temperature-lowering at the temperature-lowering speed listed in
Table 2-1 and Table 2-2 to be 500.degree. C. (the temperature to
the .alpha.+.beta. phase); immediately, temperature-raising at the
temperature-raising speed listed in Table 2-1 and Table 2-2 to be
900.degree. C. (the temperature to the .beta. single phase);
maintaining this temperature for 1 hour; and finally, quenching
from 900.degree. C. by cold water cooling.
[0088] FIG. 2-1 and FIG. 2-2 are charts illustrating the examples
of respective process, and the working ratio of cold-working and
the numbers of repetition cycles of the cold-workings and
intermediate annealings were changed to be as listed in Table 2-1
and Table 2-2, to carry out the respective process. In Table 2-1
and Table 2-2, the working ratios in the respective cold workings
(the working ratio by cold-wire-drawing in Examples) indicates one
time working ratio.fwdarw.second time working ratio.fwdarw.third
time working ratio.fwdarw. . . . working ratios, in order, from the
left side to the right side in the column of "cold-working ratio
(%)". Further, the numbers of repetition cycles of the intermediate
annealings and cold-workings indicate "the numbers of cycles of
cold-workings". In other words, before the respective
cold-wire-drawings [Step 2-2], the intermediate annealing [Step
2-1] at 500.degree. C. for 1 hour was carried out, and then, the
respective cold-wire-drawings [Step 2-2] in the numbers of cycles
(the numbers of cycles in Tables) of cold-working ratios and
cold-workings listed in Table 2-1 and Table 2-2 were carried out.
Further, in FIG. 2-1 and FIG. 2-2, the aging-heating [Step 4] was
omitted, but was carried out as the following conditions to all
Test Examples.
[0089] As described above, there were Test Examples without
carrying out neither of intermediate annealing [Step 2-1] nor
cold-working [Step 2-2], and also, there were Test examples that
the second or third intermediate annealings and cold-workings were
carried out or were not carried out.
[0090] Hereinafter, representative working process examples will be
described along with the rod diameters and working ratios.
Rod Working Process Example 1
[0091] Round rod with diameter .phi.20 mm.times.length L 500 mm
(hot forged up)
[0092] Round rod with diameter .phi.15 mm.times.length L 890 mm
(hot forged up) (working ratio of 43%)
[0093] Round rod with diameter .phi.12 mm.times.length L 1,390 mm
(cold-wire-drawn up) (working ratio of 36%)
[0094] Round rod with diameter .phi.10 mm.times.length L 2,000 mm
(cold-wire-drawn up) (working ratio of 36%.fwdarw.31.fwdarw.%)
[0095] Round rod with diameter .phi.8 mm.times.length L 3,120 mm
(cold-wire-drawn up) (working ratio of
36%.fwdarw.31%.fwdarw.36%)
Rod Working Process Example 2
[0096] Round rod with diameter .phi.20 mm.times.length L 500 mm
(hot forged up)
[0097] Round rod with diameter .phi.17 mm.times.length L 690 mm
(hot forged up) (working ratio of 28%)
[0098] Round rod with diameter .phi.12 mm.times.length L 1,380 mm
(cold-wire-drawn up) (working ratio of 50%)
Rod Working Process Example 3
[0099] Round rod with diameter .phi.20 mm.times.length L 500 mm
(hot forged up)
[0100] Round rod with diameter .phi.18.7 mm.times.length L 570 mm
(hot forged up) (working ratio of 13%) [0101] Round rod with
diameter .phi.15 mm.times.length L 885 mm (cold-wire-drawn up)
(working ratio of 36%)
[0102] Round rod with diameter .phi.12 mm.times.length L 1,380 mm
(cold-wire-drawn up) (working ratio of 36%.fwdarw.36%)
[0103] Rod specimens thus obtained, which were subjected through
the working and heat treatment processes, and to final quenching
(rapid cooling) by water cooling, thereby for obtaining samples of
the .beta. (BCC) single phase.
[0104] The respective sample was, then, subjected to age-heating at
200.degree. C. for 15 minutes.
[0105] Among Comparative Examples, the rods of Comparative Examples
3 to 8 were obtained in the same manner as in Examples 1 to 23,
except for Comparative Examples 4 and 5, in which the productions
were stopped due to the forging cracks occurred in the mid way of
productions. On the other hand, the rods of Comparative Examples 1
and 2 were obtained in the same manner as in Examples 1 to 23,
except that, in the memory heat treatment of Examples 1 to 23, the
temperature-lowering step [Step 3-2] (.beta..fwdarw..alpha.+.beta.)
was carried out at the temperature-lowering speed of 150.degree.
C./minute of the rapid temperature-lowering (Comparative Example 2)
or the temperature-raising step [Step 3-3]
(.alpha.+.beta..fwdarw..beta.) was carried out at the
temperature-raising speed of 150.degree. C./minute of the rapid
temperature-raising (Comparative Example 1).
[0106] Among those, Comparative Examples 1 and 2 are Test Examples
simulating JP-A-2001-20026 (Patent Literature 2) and WO 2011/152009
A1 (Patent Literature 3), respectively. In JP-A-2001-20026 (Patent
Literature 2) and WO 2011/152009 A1 (Patent Literature 3), any
kinds of reviews are not carried out on the temperature-lowering
speed or temperature-raising speed at the time of carrying the
memory heat treatment out, and thus, in detail, there are no
disclosures in that the tests are carried out using what kinds of
the temperature-raising speed or temperature-lowering speed. Thus,
as the temperature-raising speed or temperature-lowering speed that
is conventionally and generally used, the tests were carried out at
rapid speeds (rapid temperature-raising or rapid
temperature-lowering) that is outside of the slow
temperature-raising or slow cooling as defined in the present
invention.
[0107] As another Comparative Examples, the rods listed in Table
2-2 (Comparative Examples 7 and 8) were obtained in the same manner
as the present invention but using copper alloys containing Ni in
the too high contents that were outside of the range defined in the
present invention as indicated in Table 1-1. It was confirmed that
the Comparative Examples 7 and 8 were poor in quench-hardening
sensitivity, and also poor in superelastic characteristics.
[0108] For evaluating the superelastic characteristics, the stress
loading-unloading by a tensile test was carried out, to obtain a
stress-strain curve (S-S curve), thereby for obtaining and
evaluating a residual deformation and an elongation. For the
tensile test, three test pieces (N=3) were cut out from one
specimen, to test. In the following test results, the residual
strain and elongation were the average value obtained from those
three values.
[0109] The methods for tests and evaluations are described in
detail below.
a-1. Grain Size of Rod
[0110] The samples were prepared by cutting each of the rods at any
locations of longitudinal direction and then cutting the half of
the cut rod. The cut length a (mm) was not particularly defined,
but was five times or more of the diameter thereof. The cross
sections of the samples were polished, and then, etched with
aqueous ferric chloride solution, and the microstructures thereof
were photographed. The schematic diagram is illustrated in FIG. 1.
When the number of points, in which the edge lines ((1) and (3))
and center line ((2)) of the longitudinal direction of the cross
section intersect with the grain boundary, is defined as n, the
grain size d (mm) is determined by the following formula.
d=3.times.a/n
[0111] Among the grains of the rods, in which the grain size was
measured by the above-described method, the case where the region,
in which the grain sizes were the radius of the rod or more, was
90% or more of the whole length, was judged excellent and was rated
as "A"; and the case where the region was less than 90%, was judged
poor and was rated as "D".
[0112] The case where the grain average size (the average grain
size to the grains satisfying the following size) of the respective
grains of the rod, which was the diameter of the rod or more, in
which the grain size was the radius of the rod or more, was judged
excellent and was rated as "A"; the case where the average grain
size was 80% of the diameter of the rod or more and was less than
the diameter of the rod, was determined good and was rated as "B";
and the case where the average grain size was less than 80% of the
diameter of the rod, was judged poor and was rated as "D".
b. Superelastic Characteristics [Residual Strain (%) after 6%
Deformation]
[0113] A stress-strain curve (S-S curve) was determined by
performing a tensile test, and the residual strain was determined
and evaluated.
[0114] Three test pieces each having a length of 150 mm were cut
out from each of the specimens and supplied to the test. The
residual strain after 6% deformation was determined from the
stress-strain curve (S-S curve), and the values are presented in
the tables.
[0115] Regarding the test conditions, the tensile test of
alternately repeating strain loading and elimination by repeatedly
loading predetermined strains of different levels over a gauge
length of 25 mm, while temporarily increasing the amount of strain
from 1% to 8% by 1% in each step, was carried out at a test rate of
2%/min. The cycle of strain loading used herein was as follows: as
0 MPa (strain at zero load).fwdarw.1%.fwdarw.0
MPa.fwdarw.2%.fwdarw.0 MPa.fwdarw.3%.fwdarw.0 MPa.fwdarw.4%
MPa.fwdarw.5%.fwdarw.0 MPa.fwdarw.6%.fwdarw.0
MPa.fwdarw.7%.fwdarw.0 MPa.fwdarw.8%.fwdarw.0 MPa, the loading and
unloading of the load were repeated by turns alternately, and while
the strain at the time of loading was increased from 1% by 1% each,
the loading and unloading of eight strain were repeated till adding
8% of the loading strain.
[0116] The case where the residual strain was 0.2% or less, was
judged to have excellent superelastic characteristics and was rated
as "A"; the case where the residual strain was more than 0.2% but
not more than 0.5%, was judged to have satisfactory superelastic
characteristics and was rated as "B"; the case where the residual
strain was more than 0.5% but not more than 1.0%, was judged to
have acceptable superelastic characteristics and was rated as "C";
and the case where the residual strain was large such as more than
1.0%, was judged to have unacceptable superelastic characteristics
and was rated as "D".
[0117] For the representative residual strain, a stress-strain
curve (S-S curve) was illustrated in FIG. 3a and FIG. 3b. FIG. 3a
illustrates the rod of Example (Example 1), and FIG. 3b illustrates
the rod of Comparative Example (Comparative Example 2),
respectively.
c. Elongation (El) (%)
[0118] The elongation at breakage was measured, according to the
method defined in JIS H7103.
[0119] The case where the elongation was 10% or more, was judged
excellent and was rated as "A"; the case where the elongation was
8% or more but less than 10%, was judged satisfactory and was rated
as "B"; the case where the elongation was 6% or more but less than
8%, was judged acceptable and was rated as "C"; and the case where
the elongation was less than 6%, was judged poor and was rated as
"D".
d. Quench-Hardening Sensitivity
[0120] For the quench-hardening sensitivity, the amount of
precipitation of the .alpha. phase obtained when a sample was
cooled at a cooling speed of 300.degree. C./sec after heating, was
evaluated as the volume proportion based on an image analysis of
SEM images.
[0121] The case where the volume proportion of the .alpha. phase
was 10% or less, was judged to be excellent in quench-hardening
sensitivity and was rated as "A"; and the case where the volume
proportion was more than 10%, was judged to be poor in
quench-hardening sensitivity and was rated as "D".
[0122] The results are shown in Tables 2-1 to 2-2.
TABLE-US-00001 TABLE 1-1 Alloying elements Alloy (mass %) No. Al Mn
Others Remarks 1 8.1 10.7 -- This 2 8.1 11.1 -- invention 3 8.2
19.5 -- 4 8.1 5.5 -- 5 3.5 10.1 -- 6 9.5 11.0 -- 7 8.1 10.2 Co 0.5
8 8.1 10.2 Fe 0.5 9 8.1 9.0 Ni 1.0 10 2.0 11.0 -- Comparative 11
12.0 11.0 -- example 12 8.0 4.0 -- 13 8.0 24.0 -- 14 8.0 9.0 Ni 2.0
15 8.0 9.0 Ni 2.0, Fe 0.5 Note: `--` means not contained The
balance was Cu and unavoidable impurities
TABLE-US-00002 TABLE 1-2 Alloy Alloying elements (mass %) No. Al Mn
Ti V Cr Si Sn Zn Remarks 16 8.1 10.2 0.5 -- -- -- -- -- This 17 8.1
10.2 -- 0.5 -- -- -- -- invention 18 8.1 10.2 -- -- 0.5 -- 0.1 --
19 8.1 10.2 0.3 -- -- 0.05 -- -- 20 8.1 10.2 -- 0.1 -- -- 0.5 -- 21
8.1 10.2 -- 0.1 -- -- -- 0.5 22 8.1 10.2 -- -- 0.4 -- 0.1 -- 23 8.1
10.2 0.2 -- 0.3 -- -- -- Note: `--` means not contained The balance
was Cu and unavoidable impurities
TABLE-US-00003 TABLE 2-1 Rod Shape memory heat-treatment Cold- The
number diameter Temp.-lowering Temp.-raising speed Alloy working
(times) of cycles of specimen speed to .alpha. .fwdarw. .beta. +
.alpha. to .beta. + .alpha. .fwdarw. .beta. Remarks No. ratio (%)
in cold-working (mm) (.degree. C./min) (.degree. C./min) Ex 1 1 --
-- 15 1 1 Ex 2 1 -- -- 15 1 3 Ex 3 1 -- -- 15 3 1 Ex 4 1 -- -- 15 1
10 Ex 5 1 -- -- 15 10 1 Ex 6 1 -- -- 15 100 100 Ex 7 1 -- -- 15 1 1
Ex 8 2 -- -- 15 1 1 Ex 9 3 -- -- 15 1 1 Ex 10 4 -- -- 15 1 1 Ex 11
5 -- -- 15 1 1 Ex 12 6 -- -- 15 1 1 Ex 13 7 -- -- 15 1 1 Ex 14 8 --
-- 15 1 1 Ex 15 9 -- -- 15 1 1 Ex 16 16 -- -- 15 1 1 Ex 17 17 -- --
15 1 1 Ex 18 18 -- -- 15 1 1 Ex 19 19 -- -- 15 1 1 Ex 20 20 -- --
15 1 1 Ex 21 21 -- -- 15 1 1 Ex 22 22 -- -- 15 1 1 Ex 23 23 -- --
15 1 1 Ex 24 1 36 1 12 1 3 Ex 25 1 50 1 12 1 3 Ex 26 1 36 + 36 2 12
1 3 Ex 27 1 36 + 31 + 36 3 8 1 3 Ex 28 1 -- -- 20 1 1 Ratio of av.
Super-elasticity Quench-hardening Region (%) in which grain size
performance sensitivity the respective grain [grain size/rod
[Residual strain (%) El [.alpha.-phase Remarks size is a rod radius
or more diameter] when 6% deformed] (%) occupied ratio] Ex 1 A 99 A
1.3 A 0.13 A 16.2 A 0.1% Ex 2 A 94 B 0.8 B 0.43 B 9.5 A 0.1% Ex 3 A
95 B 0.9 B 0.26 B 9.8 A 0.1% Ex 4 A 92 B 0.8 C 0.64 B 8.9 A 0.1% Ex
5 A 94 B 0.9 B 0.35 B 9.4 A 0.1% Ex 6 A 91 B 0.8 C 0.90 B 8.2 A
0.1% Ex 7 A 99 A 1.3 A 0.10 A 15.8 A 0.1% Ex 8 A 99 A 1.4 A 0.17 A
16.0 A 0.1% Ex 9 A 99 A 1.0 A 0.18 A 10.4 A 0.1% Ex 10 A 99 A 1.2 A
0.10 A 11.9 A 0.1% Ex 11 A 99 A 1.1 A 0.17 A 10.5 A 0.1% Ex 12 A 99
A 1.0 A 0.13 A 10.6 A 0.1% Ex 13 A 99 A 1.3 A 0.12 A 12.4 A 0.1% Ex
14 A 99 A 1.2 A 0.14 A 12.7 A 0.1% Ex 15 A 99 A 1.2 A 0.12 A 13.1 A
1.7% Ex 16 A 99 A 1.1 A 0.15 A 11.2 A 0.1% Ex 17 A 99 A 1.4 A 0.16
A 12.0 A 0.1% Ex 18 A 99 A 1.3 A 0.14 A 12.5 A 0.1% Ex 19 A 99 A
1.2 A 0.15 A 14.6 A 0.1% Ex 20 A 99 A 1.4 A 0.11 A 12.9 A 0.1% Ex
21 A 99 A 1.2 A 0.15 A 13.1 A 0.1% Ex 22 A 99 A 1.3 A 0.13 A 12.1 A
0.1% Ex 23 A 99 A 1.2 A 0.17 A 11.8 A 0.1% Ex 24 A 97 A 1.1 A 0.14
A 12.1 A 0.1% Ex 25 A 99 A 1.4 A 0.10 A 15.4 A 0.1% Ex 26 A 99 A
1.4 A 0.09 A 14.8 A 0.1% Ex 27 A 99 A 1.6 A 0.07 A 16.3 A 0.1% Ex
28 A 99 A 1.0 A 0.14 A 14.7 A 0.1% Note: `Ex` means example
according to this invention.
TABLE-US-00004 TABLE 2-2 Rod Shape memory heat-treatment Cold- The
number diameter Temp.-lowering Temp.-raising speed Alloy working
(times) of cycles of specimen speed to .beta. .fwdarw. .beta. +
.alpha. to .beta. + .alpha. .fwdarw. .beta. Remarks No. ratio (%)
in cold-working (mm) (.degree. C./min) (.degree. C./min) CEx 1 1 --
-- 15 1 150 CEx 2 1 -- -- 15 150 1 CEx 3 10 -- -- 15 1 1 CEx 4 11
Cracked in forging, impossible to work CEx 5 12 Cracked in forging,
impossible to work CEx 6 13 -- -- 15 1 1 CEx 7 14 -- -- 15 1 1 CEx
8 15 -- -- 15 1 1 Ratio of av. Super-elasticity Quench-hardening
Region (%) in which grain size performance sensitivity the
respective grain [grain size/rod [Residual strain (%) El
[.alpha.-phase Remarks size is a rod radius or more diameter] when
6% deformed] (%) occupied ratio] CEx 1 D 42 D 0.4 D 1.88 C 6.2 A
0.1% CEx 2 D 59 D 0.7 D 1.20 C 7.8 A 0.1% CEx 3 A 93 B 0.8 D 4.29 A
18.1 A 0.1% CEx 4 Cracked in forging, impossible to work CEx 5
Cracked in forging, impossible to work CEx 6 A 95 B 0.9 D 4.73 A
19.5 A 0.1% CEx 7 A 97 A 1.1 D 3.09 A 12.5 D 20.3% CEx 8 A 96 A 1.2
D 2.98 A 12.1 D 19.4% Note: `CEx` means comparative example.
[0123] Examples 1 to 12 were Test Examples to the alloy
compositions, in which essentially adding elements were only
contained and their contents (composition ratio) were variously
changed. Examples 13 to 15 and 16 to 23 were Test Examples to
various alloy compositions, in which optionally adding elements
(small amounts of optionally adding elements) were added to the
essentially adding elements. Further, Examples 1 to 6 and 24 to 28
were Test Examples, in which the production conditions were
variously changed to Examples 7 to 23.
[0124] As is apparent from the results shown in the tables, and as
shown from the results of Examples 1 to 28, the materials (rods),
each of which satisfy the grain size distribution of the given
large grain size and the average grain size thereof as defined in
the present invention, can be obtained, by satisfying the given
production conditions (for example, the temperature-lowering speed
and temperature-raising speed at the time of the memory heat
treatment, and the like) as defined in the present invention, and
also making the alloy compositions to be in the preferred range of
the present invention, regardless of whether the intermediate
annealing after hot working or the cold-working thereafter was
carried out, or not. Thus, the desired excellent superelastic
characteristics can be obtained, and also the elongation and
quench-hardening sensitivity can become excellent.
[0125] On the other hand, for Comparative Examples 1 and 2, since
the temperature-raising speed in [Step 3-3] or the
temperature-lowering speed in [Step 3-2] in the memory heat
treatment was too fast, it was difficult to satisfy the grain size
distribution of the grain having the predetermined large grain size
as defined in the present invention, and also it was difficult to
satisfy the average grain size thereof. Thus, each of Comparative
Examples 1 and 2 did not exhibit desired superelastic
characteristics, and also, was small in improvement of elongation.
For Comparative Example 3, the content of Al was too small, and for
Comparative Example 6, the content of Mn was too much. Thus, each
of Comparative Examples 3 and 6 satisfied the grain size
distribution of the grain of the predetermined large grain size as
defined in the present invention and the average grain size
thereof, but did not exhibit the desired superelastic
characteristics. For Comparative Example 4, the content of Al was
too large, and for Comparative Example 5, the content of Mn was too
small. Thus, with respect to Comparative Examples 4 and 5, the
workability was poor, the cracks were occurred in the
forging-working, and it was impossible to produce the samples. For
Comparative Examples 7 and 8, Ni was contained in the alloy
component at a too large content, and thus, they satisfied the
grain size distribution of the grain of the predetermined large
grain size as defined in the present invention and the average
grain size thereof. However, in the microstructures of those
materials (rods) of Comparative Examples 7 and 8, it was confirmed
that the precipitation of the .alpha. phase was occurred, the
quench-hardening sensitivity was poor, and the desired superelastic
characteristics was impossible to exhibit.
[0126] Further, the test results were omitted but not shown.
However, for the case of the rod, in which after the hot working,
only the intermediate annealing was carried out, and after the
intermediate annealing, the cold working was not carried out and
the memory heat treatment was carried out, the similar results as
those Examples can be obtained.
Example 2
[0127] Samples (specimens) of sheets were produced under the
following conditions.
[0128] As the copper alloys that give the compositions as indicated
in Table 1-1 and Table 1-2, pure copper, pure Mn, pure Al, and
materials of other optionally adding alloying elements were
subjected respectively to melting in a high-frequency induction
furnace. The copper alloys thus melted were cooled, to obtain
ingots with diameter of 80 mm.times.length of 300 mm. The ingots
thus obtained were subjected to hot forging at 800.degree. C., to
obtain sheets with sheet thickness 15 mm and sheet width 30 mm.
[0129] The sheets were further subjected to hot rolling, to obtain
sheets with sheet thickness of 10 mm, and if necessary, the sheets
were subjected to cold rolling, to obtain sheets with the sheet
thicknesses as indicated in Table 2-3 and Table 2-4 with the
conditions as follows.
[0130] In the similar manner as the rods, according to the
respective working and heat treatment process as illustrated in
FIG. 2-1 or FIG. 2-2, the working and heat treatment were carried
out at the conditions listed in Table 2-3 and Table 2-4. In detail,
after the hot working [Step 1], the intermediate annealing [Step
2-1] and the cold-wire-drawing [Step 2-2] were not carried out, and
the memory heat treatment [Step 3] was carried out (Examples 29 to
51, Example 56, respective Comparative Examples) (Process of FIG.
2-1), or after the hot working [Step 1], the intermediate annealing
[Step 2-1] at 500.degree. C. for 1 hour and then the
cold-wire-drawing [Step 2-2] were carried out once each or were
repeatedly carried out at a plurality of times (Examples 52 to 55)
(Process of FIG. 2-2). For all the cases subjected to any kinds of
those processes, then, the sheets in Examples and Comparative
Examples, which have the sheet thicknesses listed in Table 2-3 and
Table 2-4, were prepared by: temperature-raising at the
temperature-raising speed of 30.degree. C./minutes to be
900.degree. C. (the temperature to the .beta. single phase);
maintaining this temperature for 5 minutes; temperature-lowering at
the temperature-lowering speed listed in Table 2-3 and Table 2-4 to
be 500.degree. C. (the temperature to the .alpha.+.beta. phase);
immediately, temperature-raising at the temperature-raising speed
listed in Table 2-3 and Table 2-4 to be 900.degree. C. (the
temperature to the (3 single phase); maintaining this temperature
for 1 hour; and finally, quenching from 900.degree. C. by cold
water cooling.
[0131] The explanations about FIG. 2-1 and FIG. 2-2 and Table 2-3
and Table 2-4 were the same as FIG. 2-1 and FIG. 2-2 and Table 2-1
and Table 2-2 in the case of the rods.
[0132] As described above, there were Test Examples without
carrying out neither of intermediate annealing [Step 2-1] nor
cold-working [Step 2-2], and also, there were Test examples that
the second or third intermediate annealings and cold-workings were
carried out or were not carried out.
[0133] Hereinafter, representative working process examples will be
described along with the sheet thicknesses and working ratios.
Sheet Working Process Example 1
[0134] Sheet thickness 15 mm.times.sheet width 30 mm.times.length L
500 mm (hot forged up)
[0135] Sheet thickness 10 mm.times.sheet width 33 mm.times.length L
680 mm (hot rolled up)
[0136] Sheet thickness 6 mm.times.sheet width 35 mm.times.length L
1,070 mm (hot rolled up)
[0137] Sheet thickness 4 mm.times.sheet width 35 mm.times.length L
1,600 mm (cold rolled up, working ratio of 33%)
[0138] Sheet thickness 2.5 mm.times.sheet width 35 mm.times.length
L 2,560 mm (cold rolled up, working ratio of 33%.fwdarw.37%)
[0139] Sheet thickness 1.5 mm.times.sheet width 35 mm.times.length
L 4,270 mm (cold rolled up, working ratio of
33%.fwdarw.37%.fwdarw.40%)
Sheet Working Process Example 2
[0140] Sheet thickness 6 mm.times.sheet width 35 mm.times.length L
1,070 mm (hot forged up)
[0141] Sheet thickness 3 mm.times.sheet width 35 mm.times.length L
2,140 mm (cold rolled up, working ratio of 50%)
[0142] Sheet specimens thus obtained, which were subjected through
the working and heat treatment processes, and to final quenching
(rapid cooling) by water cooling, thereby for obtaining samples of
the 6 (BCC) single phase.
[0143] The respective sample was, then, subjected to age-heating at
200.degree. C. for 15 minutes.
[0144] Among Comparative Examples, the sheets of Comparative
Examples 11 to 16 were obtained in the same manner as in Examples
29 and the like, except for Comparative Examples 12 and 13, in
which the productions were stopped due to the forging cracks
occurred in the mid way of productions. On the other hand, the
sheets of Comparative Examples 9 and 10 were obtained in the same
manner as in Examples 29 to 51, except that, in the memory heat
treatment of Examples 29 and the like, the temperature-lowering
step [Step 3-2] (6.fwdarw..alpha.+6) was carried out at the
temperature-lowering speed of 150.degree. C./minute of the rapid
temperature-lowering (Comparative Example 10) or the
temperature-raising step [Step 3-3] (.alpha.+.beta..fwdarw..beta.)
was carried out at the temperature-raising speed of 150.degree.
C./minute of the rapid temperature-raising (Comparative Example
9).
[0145] Among those, Comparative Examples 9 and 10 are Test Examples
simulating JP-A-2001-20026 (Patent Literature 2) and WO 2011/152009
A1 (Patent Literature 3), respectively. In JP-A-2001-20026 (Patent
Literature 2) and WO 2011/152009 A1 (Patent Literature 3), any
kinds of reviews are not carried out on the temperature-lowering
speed or temperature-raising speed at the time of carrying the
memory heat treatment out, and thus, in detail, there are no
disclosures in that the tests are carried out using what kinds of
the temperature-raising speed or temperature-lowering speed. Thus,
as the temperature-raising speed or temperature-lowering speed that
is conventionally and generally used, the tests were carried out at
rapid speeds (rapid temperature-raising or rapid
temperature-lowering) that is outside of the slow
temperature-raising or slow cooling as defined in the present
invention.
[0146] As another Comparative Examples, the sheets listed in Table
2-4 (Comparative Examples 15 and 16) were obtained in the same
manner as the present invention but using copper alloys containing
Ni in the too high contents that were outside of the range defined
in the present invention as indicated in Table 1-1. It was
confirmed that the Comparative Examples 15 and 16 were poor in
quench-hardening sensitivity, and also poor in superelastic
characteristics.
[0147] The characteristics of the thus-obtained sheet samples were
tested and evaluated in the same manner as in the rod samples,
except the following explanations.
a-2. Gain Size of Sheet
[0148] The samples were prepared by cutting each of the sheets in
the sheet thickness direction at any locations of longitudinal
direction and then cutting the half of the cut sheet. The cut
length a (mm) was not particularly defined, but five times or more
of the sheet width. The cross sections of the samples were
polished, and then, etched with aqueous ferric chloride solution,
and the microstructures thereof were photographed. In the same
manner as in the rod samples, the schematic diagram is illustrated
in FIG. 1 and the grain size d (mm) is determined in the same
manner as in the rod samples.
[0149] Among the respective grains of the sheets, in which the
grain size was measured by the above-described method, the case
where the region, in which the grain sizes were the half of the
sheet thickness or more, was 90% or more of the whole length, was
judged excellent and was rated as "A"; and the case where the
region was less than 90%, was judged poor and was rated as "D".
[0150] The case where the grain average size (the average grain
size to the grains satisfying such a size) of each of the grains of
the sheet, in which the grain size was the half of the sheet
thickness or more, was the thickness of the sheet or more, was
judged excellent and was rated as "A"; and the case where the
average grain size was 80% of the sheet thickness or more but less
than the sheet thickness, was determined good and was rated as "B";
and the case where the average grain size was less than 80% of the
sheet thickness, was judged poor and was rated as "D".
[0151] The results are shown in Tables 2-3 to 2-4.
TABLE-US-00005 TABLE 2-3 Sheet Shape memory heat-treatment Cold-
The number thickness Temp.-lowering Temp.-raising Alloy working
(times) of cycles of specimen speed to .beta. .fwdarw. .beta. +
.alpha. speed to .beta. + .alpha. .fwdarw. .beta. Remarks No. ratio
(%) in cold-working (mm) (.degree. C./min) (.degree. C./min) Ex 29
1 -- -- 6 1 1 Ex 30 1 -- -- 6 1 3 Ex 31 1 -- -- 6 3 1 Ex 32 1 -- --
6 1 10 Ex 33 1 -- -- 6 10 1 Ex 34 1 -- -- 6 100 100 Ex 35 1 -- -- 6
1 1 Ex 36 2 -- -- 6 1 1 Ex 37 3 -- -- 6 1 1 Ex 38 4 -- -- 6 1 1 Ex
39 5 -- -- 6 1 1 Ex 40 6 -- -- 6 1 1 Ex 41 7 -- -- 6 1 1 Ex 42 8 --
-- 6 1 1 Ex 43 9 -- -- 6 1 1 Ex 44 16 -- -- 6 1 1 Ex 45 17 -- -- 6
1 1 Ex 46 18 -- -- 6 1 1 Ex 47 19 -- -- 6 1 1 Ex 48 20 -- -- 6 1 1
Ex 49 21 -- -- 6 1 1 Ex 50 22 -- -- 6 1 1 Ex 51 23 -- -- 6 1 1 Ex
52 1 33 1 4 1 3 Ex 53 1 50 1 3 1 3 Ex 54 1 33 + 37 2 2.5 1 3 Ex 55
1 33 + 37 + 40 3 1.5 1 3 Ex 56 1 -- -- 10 1 1 Region (%) in which
Ratio of av. Super-elasticity Quench-hardening the respective grain
grain size performance sensitivity size is the half of sheet [grain
size/sheet [Residual strain (%) El [.alpha.-phase Remarks thickness
or more thickness] when 6% deformed] (%) occupied ratio] Ex 29 A 99
A 1.2 A 0.14 A 14.0 A 0.1% Ex 30 A 93 B 0.8 B 0.38 B 9.1 A 0.1% Ex
31 A 94 B 0.8 B 0.27 B 9.6 A 0.1% Ex 32 A 93 B 0.9 C 0.71 B 8.4 A
0.1% Ex 33 A 95 B 0.9 B 0.45 B 9.1 A 0.1% Ex 34 A 92 B 0.8 C 0.88 B
8.3 A 0.1% Ex 35 A 98 A 1.4 A 0.08 A 16.0 A 0.1% Ex 36 A 99 A 1.3 A
0.15 A 15.4 A 0.1% Ex 37 A 99 A 1.1 A 0.14 A 12.8 A 0.1% Ex 38 A 99
A 1.3 A 0.11 A 10.8 A 0.1% Ex 39 A 99 A 1.1 A 0.16 A 11.2 A 0.1% Ex
40 A 98 A 1.2 A 0.15 A 10.9 A 0.1% Ex 41 A 99 A 1.3 A 0.11 A 11.9 A
0.1% Ex 42 A 99 A 1.3 A 0.13 A 11.5 A 0.1% Ex 43 A 99 A 1.3 A 0.14
A 12.9 A 1.9% Ex 44 A 99 A 1.4 A 0.18 A 11.9 A 0.1% Ex 45 A 99 A
1.5 A 0.18 A 14.1 A 0.1% Ex 46 A 99 A 1.4 A 0.17 A 11.3 A 0.1% Ex
47 A 99 A 1.3 A 0.13 A 12.2 A 0.1% Ex 48 A 99 A 1.2 A 0.18 A 14.0 A
0.1% Ex 49 A 99 A 1.4 A 0.14 A 13.0 A 0.1% Ex 50 A 99 A 1.4 A 0.17
A 14.7 A 0.1% Ex 51 A 99 A 1.3 A 0.12 A 13.2 A 0.1% Ex 52 A 96 A
1.1 A 0.11 A 11.6 A 0.1% Ex 53 A 99 A 1.5 A 0.08 A 16.8 A 0.1% Ex
54 A 99 A 1.4 A 0.08 A 15.1 A 0.1% Ex 55 A 99 A 1.8 A 0.06 A 18.3 A
0.1% Ex 56 A 98 A 1.1 A 0.13 A 13.9 A 0.1%
TABLE-US-00006 TABLE 2-4 Sheet Shape memory heat-treatment Cold-
The number thickness Temp.-lowering Temp.-raising Alloy working
(times) of cycles of specimen speed to .beta. .fwdarw. .beta. +
.alpha. speed to .beta. + .alpha. .fwdarw. .beta. Remarks No. ratio
(%) in cold-working (mm) (.degree. C./min) (.degree. C./min) CEx 9
1 -- -- 6 1 150 CEx 10 1 -- -- 6 150 1 CEx 11 10 -- -- 6 1 1 CEx 12
11 Cracked in forging, impossible to work CEx 13 12 Cracked in
forging, impossible to work CEx 14 13 -- -- 6 1 1 CEx 15 14 -- -- 6
1 1 CEx 16 15 -- -- 6 1 1 Region (%) in which Ratio of av.
Super-elasticity Quench-hardening the respective grain grain size
performance sensitivity size is the half of sheet [grain size/sheet
[Residual strain (%) El [.alpha.-phase Remarks thickness or more
thickness] when 6% deformed] (%) occupied ratio] CEx 9 D 49 D 0.5 D
1.69 C 6.4 A 0.1% CEx 10 D 60 D 0.7 D 1.31 C 7.6 A 0.1% CEx 11 A 96
B 0.8 D 4.75 A 18.6 A 0.1% CEx 12 Cracked in forging, impossible to
work CEx 13 Cracked in forging, impossible to work CEx 14 A 92 A
1.0 D 4.63 A 18.8 A 0.1% CEx 15 A 98 A 1.2 D 2.76 A 13.4 D 18.6%
CEx 16 A 98 A 1.1 D 2.81 A 12.9 D 19.6%
[0152] Examples 29 to 40 were Test Examples to the alloy
compositions, in which essentially adding elements were only
contained and their contents (composition ratio) were variously
changed. Examples 41 to 43 and 44 to 51 were Test Examples to
various alloy compositions, in which optionally adding elements
(small amounts of optionally adding elements) were added to the
essentially adding elements. Further, Examples 29 to 34 and 52 to
56 were Test Examples, in which the production conditions were
variously changed to Examples 35 to 51.
[0153] As is apparent from the results shown in the tables, and as
shown from the results of Examples 29 to 56, the materials
(sheets), each of which satisfy the grain size distribution of the
given large grain size and the average grain size thereof as
defined in the present invention, can be obtained, by satisfying
the given production conditions (for example, the
temperature-lowering speed and temperature-raising speed at the
time of the memory heat treatment, and the like) as defined in the
present invention, and also making the alloy compositions to be in
the preferred range of the present invention, regardless of whether
the intermediate annealing after hot working or the cold-working
thereafter was carried out, or not. Thus, the desired excellent
superelastic characteristics can be obtained, and also the
elongation and quench-hardening sensitivity can become
excellent.
[0154] On the other hand, for Comparative Examples 9 and 10, since
the temperature-raising speed in [Step 3-3] or the
temperature-lowering speed in [Step 3-2] in the memory heat
treatment was too fast, it was difficult to satisfy the grain size
distribution of the grain having the predetermined large grain size
as defined in the present invention, and also it was difficult to
satisfy the average grain size thereof. Thus, each of Comparative
Examples 9 and 10 did not exhibit desired superelastic
characteristics, and also, was small in improvement of elongation.
For Comparative Example 11, the content of Al was too small, and
for Comparative Example 14, the content of Mn was too much. Thus,
each of Comparative Examples 11 and 14 satisfied the grain size
distribution of the grains of the predetermined large grain size as
defined in the present invention and the average grain size
thereof, but did not exhibit the desired superelastic
characteristics. For Comparative Example 12, the content of Al was
too large, and for Comparative Example 13, the content of Mn was
too small. Thus, with respect to Comparative Examples 12 and 13,
the workability was poor, the cracks were occurred in the
forging-working, and it was impossible to produce the samples. For
Comparative Examples 15 and 16, Ni was contained in the alloy
component at a too large content, and thus, they satisfied the
grain size distribution of the grain of the predetermined large
grain size as defined in the present invention and the average
grain size thereof. However, in the microstructures of those
materials (sheets) of Comparative Examples 15 and 16, it was
confirmed that the precipitation of the .alpha. phase was occurred,
the quench-hardening sensitivity was poor, and the desired
superelastic characteristics was impossible to exhibit.
[0155] Further, the test results were omitted but not shown.
However, for the case of the sheet, in which after the hot working,
only the intermediate annealing was carried out, and after the
intermediate annealing, the cold working was not carried out and
the memory heat treatment was carried out, the similar results as
those Examples can be obtained.
[0156] Having described our invention as related to the present
embodiments, it is our intention that the invention not be limited
by any of the details of the description, unless otherwise
specified, but rather be construed broadly within its spirit and
scope as set out in the accompanying claims.
* * * * *