U.S. patent application number 10/580896 was filed with the patent office on 2007-03-29 for method for the production of drop forge parts containing ti, zr, hf.
This patent application is currently assigned to DaimlerChrysler AG. Invention is credited to Andreas Barth.
Application Number | 20070068608 10/580896 |
Document ID | / |
Family ID | 34625400 |
Filed Date | 2007-03-29 |
United States Patent
Application |
20070068608 |
Kind Code |
A1 |
Barth; Andreas |
March 29, 2007 |
Method for the production of drop forge parts containing ti, zr,
hf
Abstract
The invention relates to a method for the production of drop
forge parts essentially comprising titanium, zirconium, hafnium or
a corresponding alloy, enabling rigidity thereof to be
increased.
Inventors: |
Barth; Andreas;
(Leinfelden-Echterdingen, DE) |
Correspondence
Address: |
AKERMAN SENTERFITT
P.O. BOX 3188
WEST PALM BEACH
FL
33402-3188
US
|
Assignee: |
DaimlerChrysler AG
|
Family ID: |
34625400 |
Appl. No.: |
10/580896 |
Filed: |
November 16, 2004 |
PCT Filed: |
November 16, 2004 |
PCT NO: |
PCT/EP04/12952 |
371 Date: |
May 26, 2006 |
Current U.S.
Class: |
148/668 ;
148/421; 148/670; 148/672 |
Current CPC
Class: |
C22C 27/00 20130101;
C22C 16/00 20130101; C22F 1/183 20130101; C22F 1/18 20130101; C22C
14/00 20130101; C22F 1/186 20130101 |
Class at
Publication: |
148/668 ;
148/670; 148/672; 148/421 |
International
Class: |
C22C 14/00 20060101
C22C014/00; C22C 16/00 20060101 C22C016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 2003 |
DE |
103 55 892.6 |
Claims
1-10. (canceled)
11. A process for production of a drop forged part made of a metal
alloy containing 80 wt. % or more Ti and/or Zr and/or Hf, wherein
the drop forged part during deforming is heated 5-15 K above the
.alpha./.beta. phase boundary to form .beta. phases and is
subsequently cooled.
12. A process according to claim 11, wherein said drop forged part
is a moving part of a motor.
13. A process according to claim 11, wherein said drop forged part
is a connecting rod, crankshaft, camshaft or a valve.
14. A process according to claim 11, wherein the material is heated
for 20-60 minutes.
15. A process according to claim 11, wherein the relaxation thermal
treatment occurs at 600-700.degree. C. after cooling.
16. A process according to claim 11, wherein the E-modulus and the
rigidity of the Ti and/or Zr and/or Hf containing materials, or
alloys thereof, are increased.
17. A process according to claim 11, wherein the alloy is a
titanium alloy containing 1-20 wt. % Zr and/or Hf and optionally
incidental amounts of other light or heavy metals.
18. A process according to claim 11, wherein the alloy is a
titanium alloy containing 5-15 wt. % Zr and/or Hf and optionally
incidental amounts of other light or heavy metals.
19. A process according to claim 11, wherein the alloy is a
titanium alloy containing 90 wt. % titanium.
20. A process according to claim 11, wherein the alloy is a
titanium alloy selected from Ti Al 6 V 4 and Ti Al 6 Fe2 Si.
21. A process according to claim 11, wherein an .alpha./.beta.
micro structure or composite material is formed.
22. A process according to claim 11, wherein the drop forge part
after forging is slowly cooled in air.
23. A drop forged part made of a metal alloy containing 80 wt. % or
more Ti and/or Zr and/or Hf, made by a process comprising: heating,
during deforming, 5-15 K above the .alpha./.beta. phase boundary to
form .beta. phases; and subsequently cooling.
24. A drop forged part as in claim 23, wherein said part is a
connecting rod, a crankshaft, a camshaft or a valve part.
25. A drop forged part made of a metal alloy containing 80 wt. % or
more Ti and/or Zr and/or Hf, made by a process comprising: heating,
during deforming, 5-15 K above the .alpha./.beta. phase boundary to
form .beta. phases; and subsequently cooling in such a manner that
the E-modulus is increased.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a national stage of PCT/EP2004/012952
filed Nov. 16, 2004 and based upon DE 103 55 892.6 filed on Nov.
29, 2003 under the International Convention.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention concerns a process for production of drop
forged parts, which are essentially comprised of titanium,
zirconium, hafnium or a corresponding alloy. Besides this, the
invention concerns drop forged parts of this type.
[0004] Titanium, in particular, is an interesting light metal,
since it is almost 50% lighter than steel. For this reason Ti, Zr
and Hf components are interesting in the manufacture of motor
vehicles, particularly if unsprung or rotating, for example,
oscillating masses are to be reduced. In this connection drop
forged parts (of bar stock, wires), in particular forged connecting
rods, crankshafts and camshafts or valve parts can be mentioned.
Titanium however exhibits, in comparison to metallic materials, a
comparatively low modulus of elasticity (abbreviated: E-modulus in
GPa; Materials Properties Handbook: Titanium Alloys, Editors:
Boyer, Welsch, Collings, ASM International, Materials Park, OH
44073-002). Thus, the E-modulus of titanium alloy is approximately
90 GPa, that of steel is approximately 210 GPa, that of Al-alloys
is approximately 70 GPa and that of Mg-alloys is approximately
30-40 GPa.
[0005] Drop forged moving titanium parts of motors, such as, for
example, connecting rods, crankshafts, camshafts and/or valve
parts, can as a result tolerate only low loads.
[0006] 2. Description of Related Art
[0007] In the state of the art, coating processes for components
are described, which lead to a hardening of the titanium alloy. DE
36 15 425 concerns a time and labor intensive plasma coating
process for improving abrasion resistance of surface layers of
titanium alloy machine components.
SUMMARY OF THE INVENTION
[0008] It is the task of the present invention to provide a process
for production of drop forge parts, which are comprised essentially
of Ti, Zr, Hf or a corresponding alloy, in which a higher E-modulus
of the drop forge parts is achieved.
[0009] The task is solved by a process, in which materials
containing 80 wt. % or more Ti and/or Zr and/or Hf, or alloys
thereof, during deformation, are heated 5-15K above the
.alpha./.beta. phase boundary (transition temperature) and
subsequently are cooled. Preferably, the heating takes place over a
period of approximately 20-60 minutes. Thereby it is achieved, that
the E-modulus and rigidity of the employed Ti, Zr, Hf materials is
increased in and during the manufacture of drop forge parts.
[0010] With the aid of the inventive process the oscillating mass
in a motor, in particular connecting rods, crankshafts and
camshafts and/or valves, can be reduced up to 35% or more, in
comparison with steel components. Advantages are achieved with
respect to improved motor dynamics, lower noise emissions,
dispensing of the Lancester counter-weight as well as savings in
fuel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Description of the figures:
[0012] FIG. 1:
[0013] .alpha./.beta. web arrangement (microstructure) of a Ti
connecting rod of Ti Al 6 Fe2 Si forged at 975.degree. C. (white
.alpha.- and grey .beta.-lamella).
[0014] FIG. 2:
[0015] .alpha./.beta. web arrangement (microstructure) of a Ti
connecting rod forged at 990.degree. C. of Ti Al 6 Fe2 Si with
isolated white .alpha. islands.
[0016] FIG. 3:
[0017] .alpha./.beta. web arrangement (microstructure) of a Ti
connecting rod of Ti Al 6 Fe2 Si deformed at 975.degree. C. and
then relaxation treated at 650.degree. C. (white .alpha.- and grey
.beta.-lamella).
DETAILED DESCRIPTION OF THE INVENTION
[0018] As the Ti, Zr, Hf materials, suited for purposes of the
invention are titanium as such, zirconium as such, hafnium as such;
preferred however are alloys containing up to 80 wt. % or more Ti
and/or Zr and/or Hf, preferably 90 wt. %. Particularly preferred
are however titanium alloys with 80 wt. % titanium, preferably 90
wt. % titanium. Zr and Hf can be contained as minor components in
the range of 1-20 wt. %, preferably 5-15 wt. %. Likewise,
incidental amounts of conventional metals can be contained, such as
Al, Si, Mg, Se, Ni, Co, Mo, V or other light and heavy metals.
Further preferred alloys for employment in motor vehicle
construction include Ti Al 6 V 4 or Ti Al 6 Fe2 Si.
[0019] In accordance with the invention, .alpha./.beta.-Ti-alloys
or, as the case may be, .alpha./.beta.-Ti containing materials are
employed which have both a high strength, cubic space-centered
.beta.-phase as well as hexagonal .alpha.-phase with high
E-modulus. In the so-called high temperature deformation, more
.beta.-phases are produced and in the low temperature deformation,
more .alpha.-phases are produced. In accordance with the invention,
deformation occurs in the .alpha./.beta. zone, and namely, with
heating 5-15.degree. C., preferably 8-10-12.degree. C. above the
.alpha./.beta. phase boundary (transition temperature). With pure
titanium, for example at 882.5.degree. C., .alpha.-Ti transitions
into .beta.-Ti (so-called .alpha./.beta. phase boundary limit),
that is, the heating should inventively occur at 887-897.degree. C.
For Ti Al 6 V 4 or Ti Al 6 Fe2 Si, the corresponding preferred
heating value is 975.degree. C..+-.15.degree. C.
[0020] The duration of heating in the indicated temperature range
is at least to twenty minutes to forty-five minutes or longer,
preferably however not longer than one hour.
[0021] Thereby, during heating, the .alpha.-low temperature phase
is replaced by the .beta.-high temperature phase in such a manner,
that an .alpha./.beta. microstructure, or as the case may be, an
inventive composite, is produced (FIG. 1), which combines the high
strength characteristics of the .beta. phase with the higher
E-modulus of the .alpha. phase. This temperature-dependent
deformation range is to be selected very narrowly, or as the case
may be, heating or deformation temperatures are to be adjusted to
.+-.15 K, preferably .+-.5 K, from the optimal deformation
temperature of 10 K above the .alpha./.beta. phase limit. Departing
from this range, then either isolated .alpha. or .beta. phases
exists in a .beta. or, as the case may be, .alpha. base matrix
(FIG. 2), so that disadvantageously the low E-modulus of the .beta.
phase results. The desired .alpha./.beta. microstructure or grain
structure can be improved inventively with respect to a stronger
interlacing of the .alpha. and .beta. phases, in that after the
deformation, it is slowly cooled in air or, as the case may be, in
a gas atmosphere. Thereby the .alpha./.beta. microstructure is
further interfused by the .alpha.-phase. As a result, an
alternating of the arrangement of the .alpha. phase and the .beta.
phase in the material is achieved. Basically, a mixed phase in an
.alpha./.beta. web structure is obtained. Inventively, after the
deformation, a relaxation treatment can follow at 650.+-.50.degree.
C. in order to achieve, besides the reduction of undesired
deformation tensions, a stronger intermixing of the .alpha./.beta.
microstructure with the .alpha.-phase with high E-modulus (FIG. 3).
Thereby, the heating or glowing time is to be limited in such a
manner that the .alpha./.beta. microstructure is not destroyed.
With these Ti connecting rods drop forged at 975.degree.
C..+-.5.degree. C., which after the deformation are slowly cooled
in air, there can be achieved in an .alpha./.beta. alloy Ti Al 6 V
with an E-modulus of 130 GPa or, as the case may be, a Ti Al 6 Fe2
Si an E-modulus of 140 GPa be realized. A subsequent relaxation
heating at 650.degree. C. brings about an additional E-modulus
increase of at least 5 GPa. The break elongation achieved by the
inventive process lies, in the case of alloys, (for example, Ti Al
6 V 4 Ti Al 6 Fe2 Si) at above 1,100 MPa or, as the case may be,
the technical elastic limit lies above 1,000 MPa. This corresponds
to the rigidity values of high stiffness .beta.-Ti alloys, which
lie above that of steel. Thus, advantageously the oscillating mass
can be reduced by up to 35%-45% in the case of Ti Al 6 Fe2 Si
connecting rods in comparison to high stiffness steel connecting
rods.
* * * * *