EP0296439A2 - Austenitic steel for valves of internal combustion engines - Google Patents

Austenitic steel for valves of internal combustion engines Download PDF

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Publication number
EP0296439A2
EP0296439A2 EP88109345A EP88109345A EP0296439A2 EP 0296439 A2 EP0296439 A2 EP 0296439A2 EP 88109345 A EP88109345 A EP 88109345A EP 88109345 A EP88109345 A EP 88109345A EP 0296439 A2 EP0296439 A2 EP 0296439A2
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EP
European Patent Office
Prior art keywords
austenitic steel
steel
carbon
internal combustion
combustion engines
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EP88109345A
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German (de)
French (fr)
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EP0296439A3 (en
EP0296439B1 (en
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Richard Dr. Dipl.-Ing. Weintz
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TRW Thomson GmbH
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TRW Thomson GmbH
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
    • C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum

Definitions

  • the invention relates to an austenitic, high-strength and hot corrosion-resistant steel for gas exchange valves of internal combustion engines.
  • powder metallurgy succeeds in producing very high-alloy steels which, because of their alloy structure, are difficult to produce in a conventional way via ingot casting, forging and rolling and with little output or no longer at all.
  • Powder metallurgy offers the possibility of cold compacting these high-alloy materials as atomized powder and then extruding them into bars with almost finished dimensions during hot extrusion.
  • the corrosion-chemical properties of the aforementioned precipitation-hardenable valve steels are also optimized with solution annealing, because only then does the high chromium content in the matrix required for corrosion protection go into solid solution.
  • the hot corrosion properties deteriorate because chromium is then preferably fixed in the precipitates and the finally coagulating precipitates and is removed from the alloy as a corrosion-protecting element.
  • the strength-increasing precipitates formed as precipitates by solution annealing and precipitation hardening are so largely aged that the coagulated precipitates can no longer contribute to increasing the strength and also impair the resistance of these steels to hot corrosion.
  • the object of the invention is to create a steel alloy of the type mentioned in the introduction, the properties of which can hardly be changed by the action of heat, in particular by the thermal stresses of the engine.
  • the solution to the invention problem is characterized by a Steel with the following alloy additives in mass percent: Carbon 0.30 - 0.70 Silicon 0.50 max.
  • valve steel proposed according to the invention would have very special properties and advantages. It was found that his behavior can be changed very little by the effects of heat; because neither by solution annealing and precipitation hardening, nor by thermal stresses in the engine could its properties be influenced more than insignificantly. This means a considerable practical advantage. Gas exchange valves made from this steel can be used without any concerns without heat treatments such as solution annealing and / or precipitation hardening.
  • the steel with the proposed composition and produced by powder metallurgy has virtually unchangeable stable mechanical properties in all in the heat treatment Motor thermal stresses to be expected.
  • its superior corrosion resistance is not only created by the heat treatment solution annealing, but is already predetermined without this and other heat treatments due to the advantageous alloy structure and the homogeneous distribution of the alloy elements due to the extremely fine-grained structure by the powder metallurgical production.
  • the good corrosion resistance is therefore not affected by the thermal stresses in the engine, which was previously not considered achievable. Disadvantages of an economic nature, which cause the required heat treatments for the conventional steels, are avoided in the steel according to the invention.
  • the steel produced according to the invention has heat resistance and wear properties without heat treatment, which are due in part to the high carbon and nitrogen content, but also to the alloying matrix consolidation mentioned, and apparently due to the fine grain and the extraordinarily fine carbide and nitride - Distribution are supported.
  • the high carbide and carbonitride content in the fine structure which is in the finest distribution, leads, despite the lack of strength-enhancing heat treatment, to such high wear resistance on the abrasively loaded valve seat that this steel appears to be particularly suitable for unarmored gas exchange valves for diesel engines on the valve seat, for one - and exhaust valves to be used.
  • the strength properties and corrosion rates of the steel according to the invention in the case of oxidative attack are compared with the corresponding values of previously known steels with a similar alloy structure.
  • the selected embodiment of the steel according to the invention had the following chemical composition in mass percent: C 0.53 Si 0.40 Mn 9.9 Cr 24.6 Ni 9.6 Mon 3.03 V 0.05 Nb 1.97 N 0.50 Weight loss in g / dm2 due to corrosion attack in air treatment Alloy according to the invention Known alloy, e.g.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Powder Metallurgy (AREA)
  • Heat Treatment Of Articles (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Abstract

For producing charge cycle valves for internal combustion engines, a steel alloy is proposed whose properties are scarcely changeable by thermal effects, especially by the thermal stresses of the engine. Such a steel is distinguished by the following alloy additions in per cent by mass: carbon 0.03 - 0.70 silicon 0.50 max. manganese 8.00 - 16.00 chromium 24.00 - 32.00 nickel 8.00 - 16.00 molybdenum 2.00 - 5.00 niobium/tantalum 1.5 - 4.00 vanadium 0.3 max. nitrogen 0.30 - 0.70

Description

Die Erfindung betrifft einen austenitischen, hochfesten und heißkorrosionsbeständigen Stahl für Gaswechselventile von Verbrennungsmotoren.The invention relates to an austenitic, high-strength and hot corrosion-resistant steel for gas exchange valves of internal combustion engines.

Die Verwendung von austenitischen Stählen zur Herstellung von Gaswechselventilen mit Chrom, Nickel und Mangan sowie Gehal­ten an Wolfram, Molybdän und Vanadium oder mit Anteilen von Niob/Tantal, Titan, Aluminium und Cer sowie entsprechenden Gehalten an Kohlenstoff und Stickstoff ist an sich bekannt und wird durch zahlreiche Schutzrechte belegt. Nur beispiels­weise seien folgende Vorveröffentlichungen genannt:
DE-PS      9 34 836
DE-AS      10 44 131
AT-PS      2 66 900
US-PS      24 96 245
US-PS      24 95 731
US-PS      26 03 738
US-PS      26 57 130
US-PS      26 71 726
US-PS      28 39 391
DE-PS      25 35 516
US-Reissue-PS      24 431The use of austenitic steels for the production of gas exchange valves with chromium, nickel and manganese as well as contents of tungsten, molybdenum and vanadium or with parts of niobium / tantalum, titanium, aluminum and cerium as well as corresponding contents of carbon and nitrogen is known per se and is known by numerous property rights are documented. For example, the following previous publications are mentioned:
DE-PS 9 34 836
DE-AS 10 44 131
AT-PS 2 66 900
U.S. Patent No. 24 96 245
U.S. Patent No. 24 95 731
U.S. Patent No. 26 03 738
U.S. Patent No. 2,657,130
U.S. Patent No. 26 71 726
U.S. Patent No. 28,39,391
DE-PS 25 35 516
U.S. Reissue PS 24,431

Bekannt ist auch die pulvermetallurgische Herstellung von austenitischen Stählen. Beispielsweise wird auf die Druck­schrift "Pulvermetallurgisch hergestellte Produkte in Edel­stahl-Rostfrei" der Fa. Avesta Nyby, Torshälla, Schweden hingewiesen.The powder metallurgical production of austenitic steels is also known. For example, reference is made to the publication "Powder metallurgically manufactured products in stainless steel" from Avesta Nyby, Torshälla, Sweden.

Es ist ferner bekannt, daß es über die Pulvermetallurgie ge­lingt, sehr hochlegierte Stähle herzustellen, die wegen ihres Legierungsaufbaues auf konventionellem Wege über Blockguß, Schmieden und Walzen nur schwierig und mit geringem Ausbringen oder gar nicht mehr herstellbar sind.It is also known that powder metallurgy succeeds in producing very high-alloy steels which, because of their alloy structure, are difficult to produce in a conventional way via ingot casting, forging and rolling and with little output or no longer at all.

Die Pulvermetallurgie bietet die Möglichkeit, diese hochle­gierten Werkstoffe als verdüstes Pulver kalt zu kompaktieren und anschließend beim Heiß-Fließpressen zu Stäben mit nahezu Fertigabmessungen zu extrudieren.Powder metallurgy offers the possibility of cold compacting these high-alloy materials as atomized powder and then extruding them into bars with almost finished dimensions during hot extrusion.

Gemeinsam ist den ausscheidungshärtbaren, hochwarmfesten, heiß­korrosionsbeständigen Ventilstählen mit Gehalten an Kohlen­stoff, Stickstoff, Chrom, Nickel und Mangan sowie möglicher­weise an Wolfram, Molybdän und Vanadium oder auch zusätzlich Niob/Tantal, Titan, Aluminium und Cer, daß deren verbesserte mechanische Eigenschaften nur durch eine Wärmebehandlung zum Ausscheidungshärten erreichbar sind, wobei im allgemeinen eine Optimierung der mechanischen Festigkeitswerte dann erzielt wird, wenn vor dem Ausscheidungshärten lösungsgeglüht wird.Common to the precipitation-hardenable, highly heat-resistant, hot-corrosion-resistant valve steels with contents of carbon, nitrogen, chromium, nickel and manganese as well as possibly of tungsten, molybdenum and vanadium or also additionally niobium / tantalum, titanium, aluminum and cerium that their improved mechanical properties can only be achieved through a Heat treatment for precipitation hardening can be achieved, wherein an optimization of the mechanical strength values is generally achieved if solution annealing is carried out before the precipitation hardening.

Die durch die meist sehr teueren Wärmebehandlungen eingestell­ten optimierten Eigenschaften, bewegen sich jedoch außerhalb der thermodynamischen Lösungsgleichgewichte der herkömmlichen Stähle, so daß sich deren mechanische Eigenschaften mit der Annäherung an das thermodynamische Gleichgewicht wieder ver­schlechtern. Die durch Wärmebehandlung erzeugten Eigenschaften besitzen somit eine nur temporäre Lebensdauer, wenn die Tem­peraturen und Zeiten während des Motorbetriebs zu einem Fort­ schreiten der Ausscheidungsreaktionen führen, was für die ho­hen Beanspruchungen der Ventile in den modernen, verbrauchs­armen Verbrennungsmotoren in aller Regel zutrifft.However, the optimized properties set by the usually very expensive heat treatments move outside the thermodynamic solution equilibria of conventional steels, so that their mechanical properties deteriorate again as the thermodynamic equilibrium is approached. The properties generated by heat treatment therefore have only a temporary service life if the temperatures and times during engine operation continue lead to excretion reactions, which generally applies to the high stresses on the valves in modern, low-consumption internal combustion engines.

Auch die korrosionschemischen Eigenschaften der vorerwähnten ausscheidungshärtbaren Ventilstähle werden mit dem Lösungs­glühen optimiert, weil erst hierdurch der für den Korrosions­schutz erforderliche hohe Chromgehalt in der Matrix in feste Lösung geht. Beim Ausscheidungshärten von während der Produk­tion lösungsgeglühten Ventilen, entweder unmittelbar während der Herstellung oder später während des Motorbetriebs, ver­schlechtern sich die Heißkorrosionseigenschaften, weil dann vorzugsweise Chrom in den Präzipitaten und den schließlich koagulierenden Ausscheidungen fixiert und der Legierung als korrosionsschützendes Element entzogen wird.The corrosion-chemical properties of the aforementioned precipitation-hardenable valve steels are also optimized with solution annealing, because only then does the high chromium content in the matrix required for corrosion protection go into solid solution. During precipitation hardening of valves annealed during production, either immediately during manufacture or later during engine operation, the hot corrosion properties deteriorate because chromium is then preferably fixed in the precipitates and the finally coagulating precipitates and is removed from the alloy as a corrosion-protecting element.

Je nach der Höhe der thermischen Belastung im Motor nähern sich also die mit großem Aufwand durch Lösungsglühen und Aus­scheidungshärten wärmebehandelten Stähle mehr oder weniger schnell und vollständig und in aller Regel unkontrolliert dem thermodynamischen Lösungsgleichgewicht, das dem Überalterungs­zustand des jeweiligen Stahls entspricht. In diesem Zustand werden die durch Lösungsglühen und Ausscheidungshärten gebil­deten festigkeitssteigernden Ausscheidungen als Präzipitate so weitgehend überaltert, daß die grob koagulierten Ausscheidun­gen dann nicht mehr zur Festigkeitssteigerung beitragen können und auch die Beständigkeit dieser Stähle gegen Heißkorrosion verschlechtern.Depending on the level of the thermal load in the engine, the steels heat-treated with great effort through solution annealing and precipitation hardening approach more or less quickly and completely and generally uncontrolled the thermodynamic solution equilibrium, which corresponds to the aging condition of the respective steel. In this state, the strength-increasing precipitates formed as precipitates by solution annealing and precipitation hardening are so largely aged that the coagulated precipitates can no longer contribute to increasing the strength and also impair the resistance of these steels to hot corrosion.

Ausgehend von diesem Stand der Technik liegt der Erfindung die Aufgabe zu Grunde, eine Stahllegierung der einleitend genann­ten Art zu schaffen, deren Eigenschaften sich durch Wärmeein­wirkungen, insbesondere durch die thermischen Beanspruchungen des Motors, kaum verändern lassen.
Die Lösung der Erfindungsaufgabe zeichnet sich durch einen Stahl mit folgenden Legierungszusätzen in Masse-Prozenten aus:
Kohlenstoff      0,30 - 0,70
Silicium      0,50 max.
Mangan      8,00 - 16,00
Chrom      24,00 - 32,00
Nickel      8,00 - 16,00
Molybdän      2,00 - 5,00
Niob/Tantal      1,5 - 4,00
Vanadium      0,3 max.
Stickstoff      0,30 - 0,70Starting from this prior art, the object of the invention is to create a steel alloy of the type mentioned in the introduction, the properties of which can hardly be changed by the action of heat, in particular by the thermal stresses of the engine.
The solution to the invention problem is characterized by a Steel with the following alloy additives in mass percent:
Carbon 0.30 - 0.70
Silicon 0.50 max.
Manganese 8.00-16.00
Chrome 24.00 - 32.00
Nickel 8.00-16.00
Molybdenum 2.00 - 5.00
Niobium / tantalum 1.5 - 4.00
Vanadium 0.3 max.
Nitrogen 0.30 - 0.70

Wenngleich erwartet werden mußte, daß ein Stahl innerhalb der Grenzen dieses Zusammensetzungsbereiches auf konventionellem Wege über Blockguß, Schmieden und Walzen schwierig herstellbar ist, so war insgesamt nicht davon auszugehen, daß der erfin­dungsgemäß vorgeschlagene Ventilstahl ganz spezielle Eigenschaf­ten und Vorteile besitzen würde. So wurde festgestellt, daß sich sein Verhalten durch Wärmeeinwirkungen nur sehr wenig ver­ändern läßt; denn weder durch Lösungsglühen und Ausscheidungs­härten, noch durch thermische Beanspruchungen im Motor konnten seine Eigenschaften mehr als nur unerheblich beeinflußt werden. Das bedeutet einen erheblichen praktischen Vorteil. Aus diesem Stahl hergestellte Gaswechselventile können nämlich ohne Wärme­behandlungen, wie Lösungsglühen und/oder Ausscheidungshärten ohne Bedenken verwendet werden.Although it had to be expected that a steel within the limits of this composition range would be difficult to produce conventionally by block casting, forging and rolling, on the whole it was not to be assumed that the valve steel proposed according to the invention would have very special properties and advantages. It was found that his behavior can be changed very little by the effects of heat; because neither by solution annealing and precipitation hardening, nor by thermal stresses in the engine could its properties be influenced more than insignificantly. This means a considerable practical advantage. Gas exchange valves made from this steel can be used without any concerns without heat treatments such as solution annealing and / or precipitation hardening.

Weitere, die Erfindung vorteilhaft ergänzende Maßnahmen sind in den Unteransprüchen enthalten.Further measures which advantageously supplement the invention are contained in the subclaims.

Der Stahl mit der vorgeschlagenen Zusammensetzung und pulverme­tallurgisch hergestellt, besitzt ohne Wärmebehandlung praktisch unveränderlich stabile mechanische Eigenschaften bei allen im Motor zu erwartenden thermischen Beanspruchungen. Außerdem wird auch seine überlegene Korrosionsbeständigkeit nicht erst durch die Wärmebehandlung Lösungsglühen erzeugt, sondern ist ohne diese und andere Wärmebehandlungen bereits auf Grund des vor­teilhaften Legierungsaufbaues und der homogenen Verteilung der Legierungselemente infolge der äußerst feinkörnigen Struktur durch die pulvermetallurgische Herstellung vorgegeben. Die gute Korrosionsbeständigkeit wird also durch die thermischen Be­anspruchungen im Motor nicht beeinflußt, was bisher nicht als erreichbar galt. Nachteile wirtschaftlicher Art, die die er­forderlichen Wärmebehandlungen bei den üblichen Stählen verur­sachen, werden bei dem erfindungsgemäßen Stahl vermieden.The steel with the proposed composition and produced by powder metallurgy has virtually unchangeable stable mechanical properties in all in the heat treatment Motor thermal stresses to be expected. In addition, its superior corrosion resistance is not only created by the heat treatment solution annealing, but is already predetermined without this and other heat treatments due to the advantageous alloy structure and the homogeneous distribution of the alloy elements due to the extremely fine-grained structure by the powder metallurgical production. The good corrosion resistance is therefore not affected by the thermal stresses in the engine, which was previously not considered achievable. Disadvantages of an economic nature, which cause the required heat treatments for the conventional steels, are avoided in the steel according to the invention.

Darüber hinaus besitzt der nach der Erfindung hergestellte Stahl ohne eine Wärmebehandlung Warmfestigkeits- und Ver­schleißeigenschaften, die zum Teil auf den hohen Kohlenstoff- ­und Stickstoffgehalt, aber auch auf die erwähnte legierungs­technische Matrixverfestigung zurückzuführen sind und offen­bar durch das Feinkorn und die außerordentlich feine Carbid- ­und Nitrid-Verteilung unterstützt werden. Der hohe Carbid- und Carbonitridanteil im Feingefüge der in feinster Verteilung vorliegt, führt trotz einer fehlenden festigkeitssteigernden Wärmebehandlung zu einem so hohen Verschleißwiderstand am abrasiv belasteten Ventilsitz, daß dieser Stahl besonders da­zu geeignet erscheint, für am Ventilsitz ungepanzerte Gaswech­selventile für Dieselmotoren, und zwar für Ein- und Auslaßven­tile, eingesetzt zu werden.In addition, the steel produced according to the invention has heat resistance and wear properties without heat treatment, which are due in part to the high carbon and nitrogen content, but also to the alloying matrix consolidation mentioned, and apparently due to the fine grain and the extraordinarily fine carbide and nitride - Distribution are supported. The high carbide and carbonitride content in the fine structure, which is in the finest distribution, leads, despite the lack of strength-enhancing heat treatment, to such high wear resistance on the abrasively loaded valve seat that this steel appears to be particularly suitable for unarmored gas exchange valves for diesel engines on the valve seat, for one - and exhaust valves to be used.

Von besonderer Bedeutung ist, daß gleichzeitig die korrosions­chemischen Eigenschaften durch den vorgeschlagenen Legierungs­aufbau in Verbindung mit der pulvermetallurgischen Herstellung trotz fehlendem Lösungsglühen optimiert werden konnten. Damit ist es gelungen, bei sehr guten mechanischen Eigenschaften einen Stahl mit sehr niedrigen Korrosionsraten sowohl bei oxi­dativem als auch bei einem Angriff in schwefelhaltiger Atmos­ phäre zu realisieren. Bei den erwähnten vorbekannten Stählen mit ähnlichem Legierungsaüfbau konnten entweder hohe Festig­keitseigenschaften durch Lösungsglühen und Ausscheidungshär­ten bei nur mäßigen Heißkorrosionseigenschaften realisiert werden oder eine hohe Heißkorrosionsfestigkeit war nur auf Kosten der mechanischen Festigkeit möglich. Das heißt, daß sich bei den vorbekannten Stählen der erwähnten Legierungs­gruppe beide Eigenschaften zur gleichen Zeit bislang weitge­hend ausgeschlossen haben.It is of particular importance that the corrosion-chemical properties could be optimized at the same time by the proposed alloy structure in connection with the powder metallurgical production in spite of the lack of solution annealing. With very good mechanical properties, it was thus possible to use a steel with very low corrosion rates, both in the case of an oxidative and an attack in a sulfur-containing atmosphere to realize the sphere. In the aforementioned known steels with a similar alloy structure, either high strength properties could be achieved by solution annealing and precipitation hardening with only moderate hot corrosion properties, or high hot corrosion resistance was only possible at the expense of mechanical strength. This means that both properties have hitherto largely been ruled out for the previously known steels of the alloy group mentioned.

In den nachstehenden Tabellen sind Festigkeitseigenschaften sowie Korrosionsraten des erfindungsgemäßen Stahls bei oxi­dativem Angriff den entsprechenden Werten vorbekannter Stähle mit ähnlichem Legierungsaufbau gegenübergestellt. Das gewähl­te Ausführungsbeispiel des erfindungsgemäßen Stahls hatte folgende chemische Zusammensetzung in Masse-Prozenten:
C      0,53
Si      0,40
Mn      9,9
Cr      24,6
Ni      9,6
Mo      3,03
V      0,05
Nb      1,97
N      0,50 Gewichtsverlust in g/dm² durch Korrosionsangriff an Luft Behandlung Erfindungsgemäße Legierung Bekannte Legierung z.B. 1.4785 750° C / 500 h 0,12 0,41 850° C / 500 h 0,60 2,83 950° C / 500 h 14,50 totaler Verlust der Proben durch Oxidation Gewichtsverlust in g/dm² durch Schwefel-Korrosion Behandlung Erfindungsgemäße Legierung Bekannte Legierung z.B. 1.4785 870° C / 80 h 2,69 6,80 Eigenschaften bei RT Behandlung Erfindungsgemäße Legierung Bekannte Legierung z. B. 1.4785 Kerbschlagzähigkeit [J/cm²] Lösungsglühen: 1180°C, 30′ 50 40 LG + 2 h 760°C ≧ 38 3,5 LG + 2 h 800°C 28 < 3 LG + 100 h 800°C 19 < 2 ohne Lösungsglühen 48 < 2 * 2 h 760°C 42 < 2 * 2 h 800°C 39 < 2 * 100 h 800°C 16 < 2 * Härte HB 2,5/187,5 Lösungsglühen: 1180°C, 30′ 347 310 LG + 4 h 760°C 342 400 LG + 4 h 800°C 340 355 ohne Lösungsglühen 350 > 400 * 4 h 760°C 342 > 400 * 4 h 800°C 335 > 400 * Zugfestigkeit Rm [N/mm²] Lösungsglühen: 1180°C, 30′ 1100 1000 LG + 4 h 760°C 1100 1350 LG + 20 h 760°C 1100 1050 ohne Lösungsglühen 1150 > 1350 * 4 h 760°C 1200 > 1350 * 20 h 760°C 1200 > 1100 * Der bekannte Werkstoff z. B. 1.4785 läßt sich im nicht lösungsgeglühten Zustand nicht verarbeiten. In the tables below, the strength properties and corrosion rates of the steel according to the invention in the case of oxidative attack are compared with the corresponding values of previously known steels with a similar alloy structure. The selected embodiment of the steel according to the invention had the following chemical composition in mass percent:
C 0.53
Si 0.40
Mn 9.9
Cr 24.6
Ni 9.6
Mon 3.03
V 0.05
Nb 1.97
N 0.50 Weight loss in g / dm² due to corrosion attack in air treatment Alloy according to the invention Known alloy, e.g. 1.4785 750 ° C / 500 h 0.12 0.41 850 ° C / 500 h 0.60 2.83 950 ° C / 500 h 14.50 total loss of samples due to oxidation Weight loss in g / dm² due to sulfur corrosion treatment Alloy according to the invention Known alloy, e.g. 1.4785 870 ° C / 80 h 2.69 6.80 Properties at RT treatment Alloy according to the invention Known alloy z. B. 1.4785 Notched impact strength [J / cm²] Solution annealing: 1180 ° C, 30 ′ 50 40 LG + 2 h 760 ° C ≧ 38 3.5 LG + 2 h 800 ° C 28 <3 LG + 100 h 800 ° C 19th <2 without solution annealing 48 <2 * 2 h 760 ° C 42 <2 * 2 h 800 ° C 39 <2 * 100 h 800 ° C 16 <2 * Hardness HB 2.5 / 187.5 Solution annealing: 1180 ° C, 30 ′ 347 310 LG + 4 h 760 ° C 342 400 LG + 4 h 800 ° C 340 355 without solution annealing 350 > 400 * 4 h 760 ° C 342 > 400 * 4 h 800 ° C 335 > 400 * Tensile strength Rm [N / mm²] Solution annealing: 1180 ° C, 30 ′ 1100 1000 LG + 4 h 760 ° C 1100 1350 LG + 20 h 760 ° C 1100 1050 without solution annealing 1150 > 1350 * 4 h 760 ° C 1200 > 1350 * 20 h 760 ° C 1200 > 1100 * The well-known material z. B. 1.4785 cannot be processed in the non-solution-annealed state.

Claims (5)

1. Austenitischer, hochfester und heißkorrosionsbeständiger Stahl für Gaswechselventile für Verbrennungsmotoren, dadurch gekennzeichnet, daß er auf pulvermetallurgischem Wege mit fol­gender chemischen Zusammensetzung in Masse-Prozenten herge­stellt ist:
Kohlenstoff      0,30 bis 0,70
Silicium      0,50 max.
Mangan      8,00 bis 16,00
Chrom      24,00 bis 32,00
Nickel      8,00 bis 16,00
Molybdän      2,00 bis 5,00
Niob/Tantal      1,50 bis 4,00
Vanadium      0,30 max.
Stickstoff      0,30 bis 0,701. Austenitic, high-strength and hot corrosion-resistant steel for gas exchange valves for internal combustion engines, characterized in that it is made by powder metallurgy with the following chemical composition in mass percent:
Carbon 0.30 to 0.70
Silicon 0.50 max.
Manganese 8.00 to 16.00
Chrome 24.00 to 32.00
Nickel 8.00 to 16.00
Molybdenum 2.00 to 5.00
Niobium / tantalum 1.50 to 4.00
Vanadium 0.30 max.
Nitrogen 0.30 to 0.70 2. Austenitischer Stahl nach Anspruch 1, dadurch gekennzeich­net, daß seine Kohlenstoff- und Stickstoffgehalte in ihrer Summe mindestens 1,10 Masse-Prozent betragen.2. Austenitic steel according to claim 1, characterized in that its carbon and nitrogen contents total at least 1.10 percent by mass. 3. Austenitischer Stahl nach den Ansprüchen 1 und/oder 2, da­ durch gekennzeichnet, daß sein Mindest-Chromgehalt so bemes­sen ist, daß er aus dem Kohlenstoff- und Stickstoffgehalt nach folgender Beziehung zu ermitteln ist:
% Cr ≧ 15 + % C x 15 + % N x 3,53. Austenitic steel according to claims 1 and / or 2, there characterized in that its minimum chromium content is such that it can be determined from the carbon and nitrogen content according to the following relationship:
% Cr ≧ 15 +% C x 15 +% N x 3.5 4. Austenitischer Stahl nach den Ansprüchen 2 und/oder 3, dadurch gekennzeichnet, daß er einen Siliciumgehalt von maxi­mal 0,50 Masse-Prozent besitzt.4. Austenitic steel according to claims 2 and / or 3, characterized in that it has a silicon content of at most 0.50 mass percent. 5. Austenitischer Stahl nach einem oder mehreren der Ansprü­che 1 bis 4, dadurch gekennzeichnet, daß er zusammen oder ein­zeln bis 2,5 Masse-Prozent der Legierungselemente Cer, Alumi­nium und Titan enthält.5. Austenitic steel according to one or more of claims 1 to 4, characterized in that it contains together or individually up to 2.5 mass percent of the alloying elements cerium, aluminum and titanium.
EP88109345A 1987-06-23 1988-06-11 Austenitic steel for valves of internal combustion engines Expired - Lifetime EP0296439B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19873720605 DE3720605A1 (en) 1987-06-23 1987-06-23 AUSTENITIC STEEL FOR GAS EXCHANGE VALVES OF COMBUSTION ENGINES
DE3720605 1987-06-23

Publications (3)

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EP0296439A2 true EP0296439A2 (en) 1988-12-28
EP0296439A3 EP0296439A3 (en) 1989-07-12
EP0296439B1 EP0296439B1 (en) 1992-05-20

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EP (1) EP0296439B1 (en)
DE (2) DE3720605A1 (en)
ES (1) ES2032491T3 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0411569A1 (en) * 1989-08-02 1991-02-06 Hitachi Metals, Ltd. Heat resistant steel for use as material of engine valve
EP0659895A2 (en) * 1993-12-22 1995-06-28 Fuji Oozx Inc. Internal combustion valve having an iron based hard-facing alloy contact surface
EP1917375A1 (en) * 2005-08-24 2008-05-07 Uddeholm Tooling Aktiebolag Steel alloy and tools or components manufactured out of the steel alloy
EP2113581A1 (en) * 2000-12-14 2009-11-04 Caterpillar, Inc. Heat and corrosion resistant cast stainless steels with improved high temperature strength and ductility
US9803267B2 (en) 2011-05-26 2017-10-31 Upl, L.L.C. Austenitic stainless steel
GB2611819A (en) * 2021-10-18 2023-04-19 Alloyed Ltd A heat-resistant austenitic stainless steel

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110236247A1 (en) 2010-03-25 2011-09-29 Daido Tokushuko Kabushiki Kaisha Heat resistant steel for exhaust valve

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2671726A (en) * 1950-11-14 1954-03-09 Armco Steel Corp High temperature articles
US2839391A (en) * 1954-10-21 1958-06-17 Armco Steel Corp Chromium-manganese alloy and products
GB803816A (en) * 1955-03-31 1958-11-05 Hadfields Ltd Corrosion resistant austenitic steel
US3401036A (en) * 1967-08-11 1968-09-10 Crucible Steel Co America Valve steel
US3561953A (en) * 1968-03-19 1971-02-09 Toyota Motor Co Ltd Austenitic heat-resisting steel containing nickel, chromium and manganese
FR2225535A1 (en) * 1973-04-12 1974-11-08 Creusot Loire

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT160410B (en) * 1941-05-26 Krupp Ag Valve cone for internal combustion engines.
US2553330A (en) * 1950-11-07 1951-05-15 Carpenter Steel Co Hot workable alloy
DE1044131B (en) * 1952-07-04 1958-11-20 Armco Int Corp Stainless steel

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2671726A (en) * 1950-11-14 1954-03-09 Armco Steel Corp High temperature articles
US2839391A (en) * 1954-10-21 1958-06-17 Armco Steel Corp Chromium-manganese alloy and products
GB803816A (en) * 1955-03-31 1958-11-05 Hadfields Ltd Corrosion resistant austenitic steel
US3401036A (en) * 1967-08-11 1968-09-10 Crucible Steel Co America Valve steel
US3561953A (en) * 1968-03-19 1971-02-09 Toyota Motor Co Ltd Austenitic heat-resisting steel containing nickel, chromium and manganese
FR2225535A1 (en) * 1973-04-12 1974-11-08 Creusot Loire

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Druckschrift der Fa. Avesta Nyby, "Pulvermetallurgisch hergestellte Produkte", S. 1-12 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0411569A1 (en) * 1989-08-02 1991-02-06 Hitachi Metals, Ltd. Heat resistant steel for use as material of engine valve
US5064610A (en) * 1989-08-02 1991-11-12 Hitachi Metals, Ltd. Heat resistant steel for use as material of engine valve
EP0659895A2 (en) * 1993-12-22 1995-06-28 Fuji Oozx Inc. Internal combustion valve having an iron based hard-facing alloy contact surface
EP0659895A3 (en) * 1993-12-22 1995-10-25 Fuji Valve Internal combustion valve having an iron based hard-facing alloy contact surface.
EP2113581A1 (en) * 2000-12-14 2009-11-04 Caterpillar, Inc. Heat and corrosion resistant cast stainless steels with improved high temperature strength and ductility
USRE41504E1 (en) 2000-12-14 2010-08-17 Caterpillar Inc. Heat and corrosion resistant cast CF8C stainless steel with improved high temperature strength and ductility
EP1917375A1 (en) * 2005-08-24 2008-05-07 Uddeholm Tooling Aktiebolag Steel alloy and tools or components manufactured out of the steel alloy
EP1917375A4 (en) * 2005-08-24 2013-03-06 Uddeholms Ab Steel alloy and tools or components manufactured out of the steel alloy
US8440136B2 (en) 2005-08-24 2013-05-14 Uddeholms Ab Steel alloy and tools or components manufactured out of the steel alloy
US9803267B2 (en) 2011-05-26 2017-10-31 Upl, L.L.C. Austenitic stainless steel
GB2611819A (en) * 2021-10-18 2023-04-19 Alloyed Ltd A heat-resistant austenitic stainless steel
WO2023067317A1 (en) * 2021-10-18 2023-04-27 Alloyed Limited A heat-resistant austenitic stainless steel

Also Published As

Publication number Publication date
DE3720605C2 (en) 1991-04-18
DE3871248D1 (en) 1992-06-25
EP0296439A3 (en) 1989-07-12
DE3720605A1 (en) 1989-01-05
EP0296439B1 (en) 1992-05-20
ES2032491T3 (en) 1993-02-16

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