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EP0035681B1 - Use of a steel having high strength and toughness - Google Patents

Use of a steel having high strength and toughness Download PDF

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Publication number
EP0035681B1
EP0035681B1 EP81101268A EP81101268A EP0035681B1 EP 0035681 B1 EP0035681 B1 EP 0035681B1 EP 81101268 A EP81101268 A EP 81101268A EP 81101268 A EP81101268 A EP 81101268A EP 0035681 B1 EP0035681 B1 EP 0035681B1
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yield
values
steel
cooling
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German (de)
French (fr)
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EP0035681A1 (en
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Helmut Dr. Ing. Brandis
Dr. Ing. Serosh
Albert Dr. Ing. Von Den Steinen
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Thyssen Stahl AG
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Thyssen Edelstahlwerke AG
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/12Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium

Definitions

  • the invention relates to the use of steel as a material for components which, after cooling in still or moving air, optionally after controlled cooling of forging temperatures or annealing temperatures above 1,150 ° C., have a structure made of ferrite and pearlite and thereby have stretch or 2 limit values of at least 490 N / nm 2 and an impact energy (measured on the DVM sample) of at least 30 J or at least 25 J.
  • a micro-alloyed carbon-manganese steel with vanadium or niobium has been used for forged components such as B. crankshafts used (DE-A-23 50 370).
  • Such steel is e.g. B. the 49 Mn VS3 (short name according to DIN).
  • the following analysis range is specified for him in the steel-iron list (material no. 1.119 9):
  • the characteristic of this steel is that after forging it at temperatures between 1,000 and 1,250 ° C, preferably in the die between 1,180 and 1,250 ° C, with subsequent storage in still or moving air, a minimum 0.2 limit of 450 N / mm 2 - without subsequent heat treatment. This value is caused by the precipitation hardening of vanadium carbides or carbonitrides.
  • the impact strength of this material is low, however, so that it can be used on certain components, such as, for example. limited the crankshaft and the connecting rod, where mechanical properties other than toughness are paramount.
  • Typical characteristic values, which at 49 MnVS 3 after annealing at approx. 1 225 ° C and after forging in the die to form crankshafts are listed in Example 1. After annealing at 1225 ° C, somewhat higher strength values are achieved with lower impact energy values than after forging in the die.
  • the strength values can be obtained by adjusting the carbon and manganese contents in the upper or lower region of the G are Renz analysis varied while the impact energy values-especially after the annealing or forging at temperatures around 1200 ° C thereby are not significantly changed.
  • the structure of the 49 MnVS 3 after treatment 1 225 ° C 0.5 h / air (example 1) can be seen in Figure 1.
  • the pre-eutectoid ferrite mainly lies on the former austenite grain boundaries, which enables the determination of the grain size at 1 225 ° C. According to the ASTM E 112 image alignment series, this structure can be assigned to image numbers 1 to 3.
  • the object of this invention is therefore to provide a steel with improved toughness with similar strength values, this being achieved by simple air cooling of annealing or hot-forming temperatures without further heat treatment.
  • the steel is particularly suitable for objects with larger cross sections, the smallest cross section of which is at least 100 cm 2 .
  • FIG. 4 Another example is the structure shown in Figure 4 of a steel containing silicon, manganese and vanadium, but with a silicon content of 0.3%, which is below that in this patent claimed range.
  • grain sizes of 2 to 3 are also estimated according to ASTM and impact energy values between 10 and 14 J at a 0.2 limit of approx. 500 N / mm 2 have been determined.
  • characteristic values were determined on the steel according to the invention after rolling or forging in the usual temperature ranges with subsequent storage in air.
  • This steel has silicon and manganese contents at the upper limit of the stressed range.
  • the values listed show that even on larger cross-sections there is a high 0.2 limit, here e.g. B. approx. 580 N / mm 2 , with at the same time low impact energy values.
  • These values are of the order of magnitude that can be achieved with low-alloy structural steels, which, however, have to be subjected to an expensive treatment.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

1. Use of a steel containing 0.3 to 0.4 % of carbon 0.65 to 1.2 % of silicon 0.55 to 1.3 % of manganese 0.05 to 0.18 % of vanadium 0 to 0.5 % of chromium 0 to 0.2 % of sulphur 0 to 0.1 % of aluminium 0 to 0.04 % of nitrogen, the remainder being iron, and impurities resulting from the melting process, as a material for components which, after cooling in still air, or in moving air, or, if appropriate, after controlled cooling from forging or annealing temperatures above 1,150 degrees C, possess a structure composed of ferrite or pearlite, associated with yield-point values and/or 0.2 % yield-strength values of not less than 490 N/mm2, and absorbed-energy values, measured in notched-bar impact tests on DVM-type test pieces, of not less than 30 J.

Description

Die Erfindung betrifft die Verwendung eines Stahls als Werkstoff für Bauteile, die nach dem Abkühlen an ruhender oder bewegter Luft gegebenenfalls nach gesteuerter Abkühlung von Schmiedetemperaturen oder von Glühtemperaturen über 1 150 °C ein Gefüge aus Ferrit und Perlit aufweisen und dabei Streck- bzw- 0,2-Grenzwerte von mindestens 490 N/nm2 und eine Kerbschlagarbeit (gemessen an der DVM-Probe) von mindestens 30 J bzw. mindestens 25 J haben.The invention relates to the use of steel as a material for components which, after cooling in still or moving air, optionally after controlled cooling of forging temperatures or annealing temperatures above 1,150 ° C., have a structure made of ferrite and pearlite and thereby have stretch or 2 limit values of at least 490 N / nm 2 and an impact energy (measured on the DVM sample) of at least 30 J or at least 25 J.

Seit etwa 10 Jahren wird ein mikrolegierter Kohlenstoff-Mangan-Stahl mit Vanadium oder Niob für geschmiedete Bauteile wie z. B. Kurbelwellen verwendet (DE-A-23 50 370). Ein solcher Stahl ist z. B. der 49 Mn VS3 (Kurzname nach DIN). Für ihn wird in der Stahl-Eisen-Liste (Werkstoff Nr. 1.119 9) nachstehender Analysenbereich angegeben :

Figure imgb0001
A micro-alloyed carbon-manganese steel with vanadium or niobium has been used for forged components such as B. crankshafts used (DE-A-23 50 370). Such steel is e.g. B. the 49 Mn VS3 (short name according to DIN). The following analysis range is specified for him in the steel-iron list (material no. 1.119 9):
Figure imgb0001

Das Merkmal dieses Stahles ist, daß er nach dem Schmieden bei Temperaturen zwischen 1 000 und 1 250°C, vorzugsweise im Gesenk zwischen 1 180 und 1 250°C, mit anschließendem Ablegen an ruhender oder bewegter Luft eine Mindest-0,2-Grenze von 450 N/mm2 - ohne eine nachträgliche Wärmebehandlung - erreicht. Dieser Wert wird durch die Ausscheidungshärtung von Vanadiumkarbiden oder -karbonitriden hervorgerufen.The characteristic of this steel is that after forging it at temperatures between 1,000 and 1,250 ° C, preferably in the die between 1,180 and 1,250 ° C, with subsequent storage in still or moving air, a minimum 0.2 limit of 450 N / mm 2 - without subsequent heat treatment. This value is caused by the precipitation hardening of vanadium carbides or carbonitrides.

Die Kerbschlagzähigkeit dieses Werkstoffes ist jedoch gering, so daß seine Verwendung sich auf bestimmte Bauteile, wie z.,B. die Kurbelwelle und den Pleuel beschränkt, bei denen andere mechanische Eigenschaften als die Zähigkeit im Vordergrund stehen. Typische Kennwerte, die an 49 MnVS 3 nach dem Glühen bei rd. 1 225 °C und nach dem Schmieden im Gesenk zu Kurbelwellen erreicht werden, sind in Beispiel 1 aufgeführt. Nach dem Glühen bei 1225°C werden etwas höhere Festigkeitswerte bei geringeren Kerbschlagarbeitswerten erzielt als nach dem Schmieden im Gesenk. Die Festigkeitswerte können durch Einstellen der Kohlenstoff- und Mangangehalte im oberen oder unteren Bereich der Grenzanalyse variiert werden, während die Kerbschlagarbeitswerte -insbesondere nach dem Glühen oder Schmieden bei Temperaturen um 1 200 °C dadurch nicht wesentlich verändert werden.The impact strength of this material is low, however, so that it can be used on certain components, such as, for example. limited the crankshaft and the connecting rod, where mechanical properties other than toughness are paramount. Typical characteristic values, which at 49 MnVS 3 after annealing at approx. 1 225 ° C and after forging in the die to form crankshafts are listed in Example 1. After annealing at 1225 ° C, somewhat higher strength values are achieved with lower impact energy values than after forging in the die. The strength values can be obtained by adjusting the carbon and manganese contents in the upper or lower region of the G are Renz analysis varied while the impact energy values-especially after the annealing or forging at temperatures around 1200 ° C thereby are not significantly changed.

Das Gefüge des 49 MnVS 3 nach der Behandlung 1 225 °C 0,5 h/Luft (Beispiel 1) ist aus Bild 1 ersichtlich. Der voreutektoidische Ferrit liegt überwiegend auf den ehemaligen Austenitkorngrenzen, wodurch die Bestimmung der bei 1 225 °C vorhandenen Korngröße ermöglicht wird. Nach der Bildrichtreihe von ASTM E 112 ist dieses Gefüge den Bildnummern 1 bis 3 zuzuordnen.The structure of the 49 MnVS 3 after treatment 1 225 ° C 0.5 h / air (example 1) can be seen in Figure 1. The pre-eutectoid ferrite mainly lies on the former austenite grain boundaries, which enables the determination of the grain size at 1 225 ° C. According to the ASTM E 112 image alignment series, this structure can be assigned to image numbers 1 to 3.

Die Kerbschlagarbeit dieses Stahls ist jedoch für viele Verwendungszwecke zu niedrig.However, the impact energy of this steel is too low for many uses.

Dieser Erfindung liegt daher nun die Aufgabe zugrunde, einen Stahl mit verbesserter Zähigkeit bei ähnlichen Festigkeitswerten bereitzustellen, wobei dies durch einfache Luftabkühlung von Glüh- bzw. Warmformgebungstemperaturen ohne weitere Wärmebehandlung erreicht werden soll.The object of this invention is therefore to provide a steel with improved toughness with similar strength values, this being achieved by simple air cooling of annealing or hot-forming temperatures without further heat treatment.

Zur Lösung dieser Aufgabe wird die Verwendung eines Stahls der in den Ansprüchen angegebenen Analyse für den eingangs genannten Zweck vorgeschlagen. Besonders eignet sich der Stahl für Gegenstände mit größeren Querschnitten, deren kleinster Querschnitt mindestens 100 cm2 beträgt.To solve this problem, the use of a steel of the analysis specified in the claims is proposed for the purpose mentioned at the beginning. The steel is particularly suitable for objects with larger cross sections, the smallest cross section of which is at least 100 cm 2 .

Die Ergebnisse von Untersuchungen haben überraschenderweise gezeigt, daß durch eine bestimmte Kombination von Silizium, Mangan und Vanadium ein feinkörniges Gefüge nach dem Glühen von Temperaturen über 1 200 °C mit anschließendem Ablegen an Luft erreicht werden kann. Dafür sind ein Siliziumgehalt von mindestens 0,65 %, ein Vanadiumgehalt von wenigstens 0,05 % und ein Mangangehalt von wenigstens 0,55% notwendig. Das durch diese Kombination der Legierungselemente erreichbare typische Gefüge nach dem Glühen bei 1225°C ist in Bild 2 abgebildet, und die augenscheinlich wahrnehmbare Korngröße liegt nach ASTM zwischen den Bildnummern 7 bis 8.The results of investigations have surprisingly shown that a fine combination of silicon, manganese and vanadium can be used to achieve a fine-grained structure after annealing at temperatures above 1200 ° C. with subsequent storage in air. This requires a silicon content of at least 0.65%, a vanadium content of at least 0.05% and a manganese content of at least 0.55%. The typical structure that can be achieved by this combination of the alloying elements after annealing at 1225 ° C is shown in Figure 2, and the apparently perceptible grain size, according to ASTM, lies between Figures 7 to 8.

Überraschend war auch die Feststellung, daß die allgemein angenommene Gleichwertigkeit von Niob und Vanadium im vorliegenden Fall nicht gilt. Vanadium wäre also durch Niob nicht ersetzbar. Die vorteilhaften Eigenschaften, die mit Vanadium erzielt werden, erreichen Stähle mit Niob statt Vanadium nicht.It was also surprising to find that the generally accepted equivalence of niobium and vanadium does not apply in the present case. Vanadium would not be replaceable with niobium. Steels with niobium instead of vanadium do not achieve the advantageous properties that are achieved with vanadium.

Fehlt eines der Elemente Silizium, Mangan oder Vanadium, so wird die voreutektoidische Ferritbildung innerhalb der ehemaligen Austenitkörner unterdrückt, und es ergibt sich somit ein grobes Sekundärkorn.If one of the elements silicon, manganese or vanadium is missing, the pre-eutectoid ferrite formation within the former austenite grains is suppressed and a coarse secondary grain is thus obtained.

Dies veranschaulicht die Gefügeaufnahme in Bild 3, die von einem Stahl stammt mit den in diesem Patent beanspruchten Gehalten an Silizium und Mangan, jedoch ohne Vanadiumzusatz. Die Korngröße beträgt 2 bis 3 nach ASTM. In diesem Zustand ist eine 0,2-Grenze von rd. 500 N/mm2 bei einer Kerbschlagarbeit von 10 bis 15 J, gemessen an der DVM-Probe, ermittelt worden.This is illustrated by the micrograph in Figure 3, which comes from a steel with the silicon and manganese contents claimed in this patent, but without the addition of vanadium. The grain size is 2 to 3 according to ASTM. In this state there is a 0.2 limit of approx. 500 N / mm 2 with an impact energy of 10 to 15 J, measured on the DVM sample, were determined.

Ein weiteres Beispiel ist das in Bild 4 dargestellte Gefüge eines Silizium, Mangan und Vanadium enthaltenden Stahls, jedoch mit einem Siliziumgehalt von 0,3 %, welcher unterhalb des in diesem Patent beanspruchten Bereichs liegt. In diesem Falle sind ebenfalls Korngrößen von 2 bis 3 nach ASTM geschätzt und Kerbschlagarbeitswerte zwischen 10 bis 14 J bei einer 0,2-Grenze von rd. 500 N/mm2 bestimmt worden.Another example is the structure shown in Figure 4 of a steel containing silicon, manganese and vanadium, but with a silicon content of 0.3%, which is below that in this patent claimed range. In this case, grain sizes of 2 to 3 are also estimated according to ASTM and impact energy values between 10 and 14 J at a 0.2 limit of approx. 500 N / mm 2 have been determined.

Die Beispiele der Vergleichsstähle, deren Gefüge in den Bildern 1, 3 und 4 abgebildet, sind, heben deutlich hervor, welche niedrigen Kerbschlagarbeitswerte (10-15 J) bei 0,2-Grenzen zwischen 500 und 570 N/mm2 erzielt werden.The examples of the comparative steels, the structure of which are shown in Figures 1, 3 and 4, clearly highlight the low impact energy values (10-15 J) achieved at 0.2 limits between 500 and 570 N / mm 2 .

Die günstige Wirkung des Gefüges des erfindungsgemäßen Stahls (Bild 2) auf die mechanischen Eigenschaften nach dem Glühen von 1 225 °C mit anschließendem Ablegen an Luft wird anhand von zwei Beispielen verdeutlicht.The favorable effect of the structure of the steel according to the invention (Figure 2) on the mechanical properties after annealing at 1 225 ° C with subsequent storage in air is illustrated by two examples.

Beispiel 2Example 2

Enthält die Kennwerte eines Stahls mit rd. 0,35 % C und mit Silizium- und Mangangehalten im unteren beanspruchten Bereich. Bei 0,2-Grenzen von rd. 500 N/mm2 -also ähnlich denjenigen der Vergleichsstähle mit den in Bildern 3 und 4 gezeigten Gefügen-, ergeben sich bedeutend höhere Kerbschlagarbeitswerte von rd. 38 J.Contains the characteristic values of a steel with approx. 0.35% C and with silicon and manganese contents in the lower stressed area. With 0.2 limits of approx. 500 N / mm 2 - similar to that of the comparative steels with the structure shown in Figures 3 and 4 - results in significantly higher notched bar impact values of approx. 38 yrs

Beispiel 3Example 3

Eine Erhöhung des Kohlenstoffgehaltes des erfindungsgemäßen Stahls von 0,33 auf 0,43 % führt zu einer höheren 0,2-Grenze von rd. 570 N/mm2 bei Kerbschlagarbeitswerten von rd. 28 J. Verglichen mit 49 MnVS 3 (Beispiel 1) hat dieser Stahl eine fast dreifach höhere Kerbschlagarbeit bei praktisch gleicher 0,2-Grenze.An increase in the carbon content of the steel according to the invention from 0.33 to 0.43% leads to a higher 0.2 limit of approx. 570 N / mm 2 with impact strength values of approx. 28 J. Compared to 49 MnVS 3 (example 1), this steel has an almost three times higher notch impact energy with practically the same 0.2 limit.

Beispiel 4Example 4

Hier wurden Kennwerte, die an dem erfindungsgemäßen Stahl nach dem Walzen oder Schmieden in den üblichen Temperaturbereichen mit anschließendem Ablegen an Luft ermittelt. Dieser Stahl weist Silizium- und Mangangehalte an der oberen Grenze des beanspruchten Bereichs auf. Den aufgeführten Werten ist zu entnehmen, daß auch an größeren Querschnitten eine hohe 0,2-Grenze, hier z. B. rd. 580 N/mm2, bei zugleich günstigen Kerbschlagarbeitswerten zu erzielen ist. Diese Werte liegen in der Größenordnung, die an niedriglegierten Baustählen erreicht werden, die aber einer aufwendigen Vergütungsbehandlung unterworfen werden müssen.Here, characteristic values were determined on the steel according to the invention after rolling or forging in the usual temperature ranges with subsequent storage in air. This steel has silicon and manganese contents at the upper limit of the stressed range. The values listed show that even on larger cross-sections there is a high 0.2 limit, here e.g. B. approx. 580 N / mm 2 , with at the same time low impact energy values. These values are of the order of magnitude that can be achieved with low-alloy structural steels, which, however, have to be subjected to an expensive treatment.

Beispiel 1example 1

Figure imgb0002
Figure imgb0002

BehandlungszustandTreatment status

Figure imgb0003
Figure imgb0003

Beispiel 2Example 2

Figure imgb0004
Figure imgb0004
Figure imgb0005
Figure imgb0005

Beispiel 3Example 3

Figure imgb0006
Figure imgb0006
Figure imgb0007
Figure imgb0007

Beispiel 4Example 4

Figure imgb0008
Figure imgb0008
Figure imgb0009
Figure imgb0009

Claims (4)

1. Use of a steel containing
Figure imgb0014
the remainder being iron, and impurities resulting from the melting process,
as a material for components which, after cooling in still air, or in moving air, or, if appropriate, after controlled cooling from forging or annealing temperatures above 1,150°C, possess a structure composed of ferrite or pearlite, associated with yield-point values and/or 0.2-% yield-strength values of not less than 490 N/mm2, and absorbed-energy values, measured in notched-bar impact tests on DVM-type test pieces, of not less than 30 J.
2. Use of a steel containing
Figure imgb0015
the remainder being iron and impurities resulting from the melting process,
as a material for components which, after cooling in still air, or in moving air, or after controlled cooling from forging or annealing temperatures above 1,150°C. possess a structure composed of ferrite and pearlite, associated with yield-point values and/or 0.2-% yield-strength values of not less than 530 N/mm2 and absorbed-energy values, measured in notched-bar impact tests on DVM-type test pieces, of not less than 25 J.
3. Use of a steel containing
Figure imgb0016
for components which, after hot-shaping by rolling, forging or pressing, the final temperatures during these hot-shaping operations being below 1,150 °C, and after subsequent cooling in still air, or in moving air, possess a ferritic/pearlitic structure, with a yield point or a 0.2-% yield-strength of not less than 550 N/mm2 and absorbed-energy values, measured in notched-bar impact tests on DVM-type test pieces, of not less than 30 J.
4. Use of a steel possessing the composition, treated according to Claim 3, and possessing properties according to Claim 3, as a material for components having a minimum cross-section of not less than 100 cm 2.
EP81101268A 1980-03-12 1981-02-21 Use of a steel having high strength and toughness Expired EP0035681B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81101268T ATE3652T1 (en) 1980-03-12 1981-02-21 USING A STEEL OF HIGH STRENGTH AND Toughness.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3009443 1980-03-12
DE3009443A DE3009443C2 (en) 1980-03-12 1980-03-12 Use of a steel of high strength and toughness

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EP0035681A1 EP0035681A1 (en) 1981-09-16
EP0035681B1 true EP0035681B1 (en) 1983-06-01

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004022248A1 (en) * 2004-05-04 2005-12-15 Zf Friedrichshafen Ag Ball element for two-part ball stud and manufacturing process
RU2441093C2 (en) * 2006-09-01 2012-01-27 Георгсмариенхютте Гмбх Steel and method of processing high-strength parts that may be separated by shearing-off

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3201204C2 (en) * 1982-01-16 1983-12-22 M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8900 Augsburg "Use of a carbon-manganese steel for components with high strength and toughness with simple heat treatment"
FI922461A7 (en) * 1992-05-29 1993-11-30 Imatra Steel Oy Ab SMIDESSTYCKE OCH DESS FRAMSTAELLNINGSFOERFARANDE
WO2013050936A1 (en) 2011-10-07 2013-04-11 Babasaheb Neelkanth Kalyani A process to improve fatigue strength of micro alloy steels, forged parts made from the process and an apparatus to execute the process

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3173782A (en) * 1962-06-13 1965-03-16 Bethlehem Steel Corp Vanadium nitrogen steel
GB1342582A (en) * 1970-03-20 1974-01-03 British Steel Corp Rail steel
DE2350370A1 (en) * 1973-10-08 1975-04-17 Volkswagenwerk Ag Forging carbon-manganese steel - micro-alloyed with vanadium or niobium and cooling in air at room temp.
BE821354A (en) * 1974-03-04 1975-04-23 A HIGH STRENGTH PROPERTY STEEL

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004022248A1 (en) * 2004-05-04 2005-12-15 Zf Friedrichshafen Ag Ball element for two-part ball stud and manufacturing process
DE102004022248B4 (en) * 2004-05-04 2007-06-14 Zf Friedrichshafen Ag Process for the production of balls or ball segments, as well as subsequently manufactured ball element for two-part ball studs
RU2441093C2 (en) * 2006-09-01 2012-01-27 Георгсмариенхютте Гмбх Steel and method of processing high-strength parts that may be separated by shearing-off

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EP0035681A1 (en) 1981-09-16
DE3009443A1 (en) 1981-09-17
DE3009443C2 (en) 1981-11-19
ATE3652T1 (en) 1983-06-15

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