U.S. patent application number 12/310588 was filed with the patent office on 2010-07-29 for steel and processing method for the manufacture of high strength, fracture-splittable machinery components.
This patent application is currently assigned to Georgsmarienhuette GmbH. Invention is credited to Roman Diederichs, Robert Lange, Axel Stueber.
Application Number | 20100186855 12/310588 |
Document ID | / |
Family ID | 38989625 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100186855 |
Kind Code |
A1 |
Diederichs; Roman ; et
al. |
July 29, 2010 |
Steel and processing method for the manufacture of high strength,
fracture-splittable machinery components
Abstract
The invention relates to a steel and a processing method for
high-strength fracture-splittable machine components that are
composed of at least two fracture-splittable parts. The steel and
method are characterized in that the chemical composition of the
steel (expressed in percent by weight) is as follows:
0.40%.ltoreq.C.ltoreq.0.60%; 0.20%.ltoreq.Si.ltoreq.1.00%;
0.50%.ltoreq.Mn.ltoreq.1.50%; 0%.ltoreq.Cr.ltoreq.1.00%;
0%.ltoreq.Ni.ltoreq.0.50%; 0%.ltoreq.Mo.ltoreq.0.20%;
0%.ltoreq.Nb.ltoreq.0.050%; 0%.ltoreq.V.ltoreq.0.30%;
0%.ltoreq.Al.ltoreq.0.05%; 0.005%.ltoreq.N.ltoreq.0.020%, the rest
being composed of iron and smelting-related impurities and residual
matter.
Inventors: |
Diederichs; Roman;
(Osnabrueck, DE) ; Stueber; Axel; (Osnabrueck,
DE) ; Lange; Robert; (Osnabrueck, DE) |
Correspondence
Address: |
COLLARD & ROE, P.C.
1077 NORTHERN BOULEVARD
ROSLYN
NY
11576
US
|
Assignee: |
Georgsmarienhuette GmbH
|
Family ID: |
38989625 |
Appl. No.: |
12/310588 |
Filed: |
July 27, 2007 |
PCT Filed: |
July 27, 2007 |
PCT NO: |
PCT/DE2007/001337 |
371 Date: |
February 27, 2009 |
Current U.S.
Class: |
148/328 ;
420/104; 420/105; 420/108; 420/109; 420/110; 420/111; 420/112;
420/119; 420/120; 420/123; 420/124; 420/127; 420/128 |
Current CPC
Class: |
C22C 38/02 20130101;
C22C 38/48 20130101; C22C 38/04 20130101; C22C 38/06 20130101; C22C
38/001 20130101; C22C 38/46 20130101 |
Class at
Publication: |
148/328 ;
420/104; 420/105; 420/108; 420/109; 420/112; 420/119; 420/120;
420/123; 420/124; 420/127; 420/128; 420/110; 420/111 |
International
Class: |
C22C 38/46 20060101
C22C038/46; C22C 38/18 20060101 C22C038/18; C22C 38/44 20060101
C22C038/44; C22C 38/40 20060101 C22C038/40; C22C 38/08 20060101
C22C038/08; C22C 38/04 20060101 C22C038/04; C22C 38/12 20060101
C22C038/12; C22C 38/26 20060101 C22C038/26; C22C 38/22 20060101
C22C038/22; C22C 38/00 20060101 C22C038/00; C22C 38/24 20060101
C22C038/24; C22C 38/28 20060101 C22C038/28 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 1, 2006 |
DE |
10 2006 041 146.3 |
Claims
1. A steel and the processing method for the manufacture of high
strength, fracture-splittable machinery components, wherein they
consist of at least two fracture-splittable parts, wherein their
chemical composition has the following components in percentages by
weight: 0.40%.ltoreq.C.ltoreq.0.60% 0.20%.ltoreq.Si.ltoreq.1.00%
0.50%.ltoreq.Mn.ltoreq.1.50% 0%.ltoreq.Cr.ltoreq.1.00%
0%.ltoreq.Ni.ltoreq.0.50% 0%.ltoreq.Mo.ltoreq.0.20%
0%.ltoreq.Nb.ltoreq.0.050% 0%.ltoreq.V.ltoreq.0.30%
0%.ltoreq.Al.ltoreq.0.05% 0.005%.ltoreq.N.ltoreq.0.020% whereby the
remainder consists of iron and impurities from the melting process
and residues.
2. A steel in accordance with claim 1, wherein its chemical
composition is the same except that:
0.10%.ltoreq.V.ltoreq.0.20%
3. A steel in accordance with claim 1, wherein its chemical
composition is the same except that:
0.020%.ltoreq.Nb.ltoreq.0.030%
4. A steel in accordance with claim 1, wherein its chemical
composition is the same except that:
0.010%.ltoreq.N.ltoreq.0.020%
5. A steel in accordance with claim 1, wherein its chemical
composition is the same except that: 0.45%.ltoreq.C.ltoreq.0.55%
0.50%.ltoreq.Si.ltoreq.0.70% 0.90%.ltoreq.Mn.ltoreq.1.10%
0.10%.ltoreq.Cr.ltoreq.0.40% 0.10%.ltoreq.Ni.ltoreq.0.30%
0.10%.ltoreq.V.ltoreq.0.20% 0.010%.ltoreq.Al.ltoreq.0.020%
0.020%.ltoreq.Nb.ltoreq.0.030% 0.010%.ltoreq.N.ltoreq.0.020%
6. A steel in accordance with claim 1, wherein its chemical
composition is the same except that: 0.45%.ltoreq.C.ltoreq.0.55%
0.50%.ltoreq.Si.ltoreq.0.70% 0.90%.ltoreq.Mn.ltoreq.1.10%
0.10%.ltoreq.Cr.ltoreq.0.40% 0.10%.ltoreq.Ni.ltoreq.0.30%
0.10%.ltoreq.V.ltoreq.0.20% 0.010%.ltoreq.Al.ltoreq.0.020%
0.020%.ltoreq.Nb.ltoreq.0.030% 0.010%.ltoreq.N.ltoreq.0.020%
0.020%.ltoreq.Ti.ltoreq.0.030%
7. A steel in accordance with claim 1, wherein its chemical
composition is the same except that: 0.45%.ltoreq.C.ltoreq.0.55%
0.50%.ltoreq.Si.ltoreq.0.70% 0.90%.ltoreq.Mn.ltoreq.1.10%
0.30%.ltoreq.Cr.ltoreq.0.40% 0%.ltoreq.Ni.ltoreq.0.20%
0.10%.ltoreq.V.ltoreq.0.20% 0.010%.ltoreq.Al.ltoreq.0.020%
0.020%.ltoreq.Nb.ltoreq.0.030% 0.015%.ltoreq.N.ltoreq.0.020%
8. The use of a steel in accordance with claim 1 to manufacture
fracture-splittable components used in the construction of
vehicles, whereby they have a predominantly pearlitic structure
from the precipitation of special carbides after forging and
controlled cooling.
9. A component in accordance with claim 8, wherein the apparent
limit of elasticity is over 750 N/mm.sup.2 after cooling down from
the forming temperature.
10. A component in accordance with claim 9, wherein the tensile
strength falls between 950 N/mm.sup.2 and 1200 N/mm.sup.2 after
cooling down from the forming temperature.
11. A component in accordance with claim 10, wherein the elongation
to fracture exceeds 10% after cooling down from the forming
temperature.
12. A component in accordance with claim 11, wherein the reduction
in area at fracture exceeds 25% after cooling down from the forming
temperature.
13. A component in accordance with claim 12, wherein it is fracture
splittable.
14. A component in accordance with claim 13, wherein it is suitable
for induction hardening.
15. A component in accordance with claim 14, wherein the mechanical
properties can be adjusted both in the material prior to forging as
well as in the component through the use of thermomechanical
treatment.
Description
[0001] The invention concerns a steel and the processing method for
the manufacture of high strength, fracture-splittable machinery
components. This material was developed, for example, for the
manufacture of crack connecting rods.
[0002] The steel must be suitable for forging or for other heat
forming processes. The heat used in the forging is dissipated by
controlled cooling to produce a largely pearlitic structure that
has an apparent limit of elasticity in excess of 750 N/mm.sup.2, a
tensile strength between 1000 and 1200 N/mm.sup.2, elongation to
fracture of over 10% and reduction in area at fracture of over 25%.
Its fracture-splittability is a particularly important feature.
[0003] The desired properties can be obtained by intentionally
creating a pearlitic structure with the precipitation of special
carbides (niobium and vanadium carbide) and of manganese sulphides
by an appropriately formulated chemical composition, controlled
temperature management during the heat forming when producing the
preliminary material as well as when forging the finished
components (thermomechanical treatment), and a suitable heat
treatment after completion of the forging or heat forming, as the
case may be.
[0004] Up to now, examples of the steels used for this purpose are
either mostly eutectoid compositions with approximately 0.7% C, 0.5
to 0.9% Mn, 0.06 to 0.07% S and possibly 0.1 to 0.2% V (C70S6,
70MnVS4), or an average carbon content of approximately 0.4%, about
1% Mn, 0.06 to 0.07% S and about 0.3% V (36MnVS4) according to
customers' technical specifications.
[0005] These steels have a predominantly pearlitic structure with
vanadium carbides and manganese sulphides and conform to
requirements regarding mechanical properties. The drawbacks in the
various known material alternatives are that the versions used to
this point need considerable resources in terms of expensive and
scarce alloying materials. Vanadium in particular is currently used
increasingly in the field of precipitation hardening
ferritic-pearlitic steels (AFP steels), making vanadium an
increasingly scarce commodity.
[0006] The aim of this invention is to avoid the cited
disadvantages by proposing a new steel which has the required
mechanical properties regarding strength (and fatigue strength)
and, additionally, good toughness characteristics in tensile tests,
combined at the same time with good splittability. The steel must
also be easy to continuously cast and forge. Furthermore, the new
steel must use fewer resources when being produced than the known
steels by partially substituting the vanadium content with niobium
using an appropriately adapted forming and cooling strategy.
[0007] The high value for the apparent limit of elasticity is
achieved, other than with the basic composition, by the
precipitation of extremely finely dispersed carbides of special
carbide formers niobium and vanadium. This requires a solution of
the present carbides before the final hot forming process as well
as controlled temperature management during the hot forming,
followed by a final cooling off stage. Finely dispersed
precipitation can be achieved, in particular, by having a low final
forming temperature, ending with slightly accelerated cooling. This
raises the apparent limit of elasticity in particular, thus
improving the elastic limit ratio considerably.
[0008] The tensile strength value of the basic composition
comprising 0.5% C, 0.6% Si, 1.0% Mn, 0.23% Cr, 0.2% Ni and 0.14% V
can be adjusted to the desired level by slightly accelerated
cooling after hot forming.
[0009] The toughness characteristic values are controlled, in
particular, by selective alloying with 0.06 to 0.07% sulphur. The
carbon content and relatively high nitrogen content also act
positively in this regard.
[0010] A crystalline fracture or macroscopic deformation is
essential for the material to split properly. This is achieved by
designing the alloy with high contents of carbon, nitrogen and
sulphur, and comparatively low contents of chromium, nickel and
molybdenum.
[0011] According to the solution proposed, the invention concerns a
steel for the manufacture of fracture-splittable components for the
vehicle industry with the following chemical composition in
percentages by weight:
[0012] 0.4%.ltoreq.C.ltoreq.0.6%; 0.2%.ltoreq.Si.ltoreq.1.0%;
0.5%.ltoreq.Mn.ltoreq.1.5%; 0%.ltoreq.Cr.ltoreq.1.0%;
0%.ltoreq.Ni.ltoreq.0.5%; 0%.ltoreq.Mo.ltoreq.0.2%;
0%.ltoreq.Nb.ltoreq.0.05%; 0%.ltoreq.V.ltoreq.0.3%;
0%.ltoreq.Al.ltoreq.0.05%; 0.005%.ltoreq.N.ltoreq.0.020%
[0013] whereby the remainder consists of iron and impurities from
the melting process.
[0014] Disadvantages of Old Alternatives? [0015] Partly the high
cost of alloying with 0.29% V (with 36MnVS4) [0016] scarcely any
alternatives to patented steel grade
[0017] Benefits of the new alternatives? [0018] Low alloying costs
(only 0.14% V) [0019] Customer not dependent on a single patented
steel grade
* * * * *