WO2016055098A1 - Alliage d'acier - Google Patents

Alliage d'acier Download PDF

Info

Publication number
WO2016055098A1
WO2016055098A1 PCT/EP2014/071440 EP2014071440W WO2016055098A1 WO 2016055098 A1 WO2016055098 A1 WO 2016055098A1 EP 2014071440 W EP2014071440 W EP 2014071440W WO 2016055098 A1 WO2016055098 A1 WO 2016055098A1
Authority
WO
WIPO (PCT)
Prior art keywords
alloy
rom
steel alloy
steel
vanadium
Prior art date
Application number
PCT/EP2014/071440
Other languages
English (en)
Inventor
John Beswick
Mohamed Sherif
Original Assignee
Aktiebolaget Skf
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Aktiebolaget Skf filed Critical Aktiebolaget Skf
Priority to DE112014007041.6T priority Critical patent/DE112014007041T5/de
Priority to PCT/EP2014/071440 priority patent/WO2016055098A1/fr
Publication of WO2016055098A1 publication Critical patent/WO2016055098A1/fr

Links

Classifications

    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
    • B22F5/106—Tube or ring forms
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
    • 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
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • C22C37/06—Cast-iron alloys containing chromium
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/36—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.7% by weight of carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/004—Dispersions; Precipitations
    • 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
    • C21D6/04—Hardening by cooling below 0 degrees Celsius
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/36—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for balls; for rollers
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races

Definitions

  • the present invention relates to the field of steels and bearings. More specifically, the present invention relates to a novel steel alloy, a bearing component comprising the steel alloy and a method of forming the bearing component.
  • Rolling element bearings are devices that permit constrained relative motion between two parts.
  • Rolling element bearings comprise inner and outer raceways and a plurality of rolling elements (balls or rollers) disposed therebetween.
  • rolling elements balls or rollers
  • Ceramic rolling elements have been considered for use in bearing applications, including highly loaded main shaft aero engines. There are, however, perceived intrinsic limitations associated with the use of ceramic materials in safety critical applications. Powder metallurgy (PM) high speed steels (HSS) offer an alternative for specific, very highly loaded, high temperature aero engine requirements.
  • PM Powder metallurgy
  • HSS high speed steels
  • the high speed steel M62 exhibits high hardness and typically comprises from 1 .25 to 1 .35 wt.% carbon, from 0.15 to 0.4 wt.% silicon, from 0.15 to 0.4 wt.% manganese, from 3.5 to 4 wt.% chromium, from 10 to 1 1 wt.% molybdenum, from 1 .8 to 2.2 wt.% vanadium, from 5.75 to 6.5 wt.% tungsten and a balance of iron and unavoidable impurities.
  • Rolling elements formed of the high speed steel M62 have been employed in high temperature aero engines.
  • Such rolling elements may be produced by re-melting and solidification techniques such as, for example, vacuum induction melting (VIM) and vacuum arc refining (VAR).
  • VIM vacuum induction melting
  • VAR vacuum arc refining
  • M62 comprises high levels of tungsten. Since tungsten is an expensive element, the cost of M62 is high. There is a need for a steel alloy having comparable hardness to M62, but which does not contain high levels of expensive elements such as, for example, cobalt and tungsten. It is an objective of the present invention to address or at least mitigate some of the problems associated with prior art or to provide a commercially acceptable alternative thereto. Summary
  • the present invention provides a cobalt-free steel alloy comprising:
  • the steel alloy typically exhibits a microstructure comprising vanadium-rich carbides and/or carbonitrides. Such a microstructure results in the steel alloy exhibiting a high hardness, for example a hardness of 60 HRC or more, typically 65 HRC or more. Accordingly, the steel alloy may be effectively used in high load environments such as, for example, aerospace bearings. Advantageously, the alloy may achieve such a high hardness without containing high levels of high cost elements such as cobalt and tungsten.
  • the steel alloy may be a bearing steel alloy.
  • conventional high-carbon steels e.g. Fe-1 C-1 .5Cr
  • Fe-1 C-1 .5Cr typically have a pearlitic structure, and therefore have to be softened prior to fabrication into a bearing component and the final hardening heat treatment.
  • One way of softening the steel involves a long heat treatment at temperatures where only cementite and ferrite are stable, causing the lamellae of cementite to spheroidise, driven by a reduction in the total amount of cementite/ferrite interfacial area.
  • Such a spheroidising heat treatment can be uneconomical, and may increase the cost of manufacturing the bearing component.
  • An alternative method of softening certain high-carbon steels is to form a so-called divorced pearlite microstructure, in which ferrite and cementite grow from the austenite in a non-cooperative manner, resulting in the formation of a ferritic matrix within which spherical cementite particles are embedded.
  • a divorced pearlite structure may be obtained by employing a particularly economical spheroidising heat treatment, i.e. a heat treatment employing relatively low temperatures and/or short heating times.
  • a particularly economical spheroidising heat treatment i.e. a heat treatment employing relatively low temperatures and/or short heating times.
  • many high carbon steels, including M62 are not able to form such a divorced pearlite structure.
  • the steel alloy of the present invention is able to form a divorced pearlite structure, meaning that it can be used to manufacture a bearing component more economically.
  • the steel alloy of the present invention may form a divorced pearlite structure after heat treatment at about 875 °C for just over 5 hours.
  • the steel alloy comprises from 2 to 3 wt.% carbon.
  • the steel alloy preferably comprises from 2.2 to 2.8 wt.% carbon, more preferably from 2.4 to 2.6 wt.% carbon, even more preferably from 2.45 to 2.55 wt.% carbon.
  • the steel alloy comprises about 2.5 wt.% carbon. In combination with the other alloying elements, this results in the desired microstructure and mechanical properties, particularly hardness.
  • the high level of carbon in the steel is necessary given the vanadium concentration of the alloy, which causes a significant amount of carbon to be tied in vanadium-rich carbides and/or carbonitrides.
  • the steel alloy comprises 4 to 6 wt.% chromium.
  • the steel alloy preferably comprises from 4.5 to 5.5 wt.% chromium, more preferably from 4.8 to 5.2 wt.% chromium, even more preferably from 4.9 to 5.1 wt.% chromium. In a preferred embodiment, the steel alloy comprises about 5 wt.% chromium.
  • Chromium acts to increase hardenability. Chromium also provides an improved corrosion resistance property to the steel. Chromium controls the stability of various forms of carbides so that no carbide is allowed to grow excessively, meaning that the steel's properties do not deteriorate during heat treatment.
  • the steel alloy comprises from 0.1 to 0.5 wt.% manganese.
  • the steel alloy preferably comprises from 0.25 to 0.45 wt.% manganese, more preferably from 0.3 to 0.4 wt.% manganese. In a preferred embodiment, the steel alloy comprises about 0.35 wt.% manganese.
  • Manganese may prevent hot-shortness of the steel.
  • the steel alloy comprises from 0.1 to 0.9 wt.% silicon.
  • the steel alloy preferably comprises from 0.2 to 0.7 wt.% silicon, more preferably from 0.3 to 0.4 wt.% silicon. In a preferred embodiment, the steel alloy comprises about 0.35 wt.% silicon.
  • Silicon may be added during the steel making process as a deoxidizer. Silicon may also act to increase strength and hardness, in particular hardness in the martensite-tempered condition. Higher levels of silicon may increase the risk of over-heating the steel during hardening (austenitisation).
  • the steel alloy comprises from 9 to 1 1 wt.% molybdenum.
  • the steel alloy preferably comprises from 9.55 to 10.5 wt.% molybdenum, more preferably from 9.8 to 10.2 wt.% molybdenum. In a preferred embodiment, the steel alloy comprises about 10 wt.% molybdenum.
  • Molybdenum acts to avoid austenite grain boundary embrittlement owing to impurities such as, for example, phosphorus. Molybdenum also acts to increase
  • Molybdenum is a strong carbide former and may contribute to secondary hardening upon tempering the steel at temperatures typically around 500 e C or above. Accordingly, the steel alloy may exhibit high hot-hardness. Molybdenum imparts toughness for heavy service, particularly to overcome peak structural loads, and provides especially heat-resistant alloys.
  • the steel alloy comprises from 6 to 8 wt.% vanadium.
  • the steel alloy preferably comprises from 6.5 to 7.5 vanadium, more preferably from 6.8 to 7.2 wt.% vanadium, even more preferably from 6.9 to 7.1 wt.% vanadium. In a preferred embodiment, the steel alloy comprises about 7 wt.% vanadium.
  • vanadium and carbon form vanadium carbides and/or cabonitrides. Vanadium carbides and carbonitrides are very hard and incredibly stable compared with other types of carbides and carbonitrides that are common in tool steels. Accordingly, the steel alloy exhibits high hardness combined with structural stability.
  • the steel alloy comprises from 2.2 to 2.8 wt.% carbon, from 4.5 to 5.5 wt.% chromium, from 0.25 to 0.45 wt.% manganese, from 0.25 to 0.45 wt.% silicon, from 9.5 to 10.5 wt.% molybdenum and from 6.5 to 7.5 wt.% vanadium.
  • Such an alloy may exhibit particularly high hardness following heat treatment, and may form a divorced pearlite structure after undergoing a particularly favourable spheroidisation heat treatment.
  • the steel alloy comprises from 2.4 to 2.6 wt.% carbon, from 4.8 to 5.2 wt.% chromium, from 0.3 to 0.4 wt.% manganese, from 0.3 to 0.4 wt.% silicon, from 9.8 to 10.2 wt.% molybdenum and from 6.8 to 7.2 wt.% vanadium.
  • Such an alloy may exhibit particularly high hardness following heat treatment, and may form a divorced pearlite structure after undergoing a particularly favourable spheroidisation heat treatment.
  • the steel alloy may optionally comprise from 0 to 0.3 wt.% copper, for example from 0.01 to 0.1 wt.% copper. This may be as a result of melting steel scrap to form the alloy.
  • the steel alloy may optionally comprise from 0 to 0.2 wt.% nickel, for example from 0.01 to 0.1 wt.% nickel. This may be as a result of melting steel scrap to form the alloy. Nickel may act to increase hardenability and impact strength.
  • the steel alloy may optionally comprise from 0 to 0.1 wt.% aluminium, for example from 0.01 to 0.1 wt.% aluminium. Aluminium may be used as a deoxidizer. Aluminium, together with nitrogen (aluminium nitrides), may also act to control the prior austenite grain size in the alloy.
  • the steel alloy may be tungsten-free. Alternatively, the steel alloy may optionally comprise from 0 to 0.1 wt.% tungsten, for example from 0.01 to 0.1 wt.% tungsten. While tungsten is preferably kept to a minimum in view of costs, small levels of tungsten may serve to avoid carbide coarsening during prolonged tempering.
  • the steel alloy may optionally comprise from 0 to 0.1 wt.%, for example from 0.01 to 0.1 wt.%, of one or more of titanium, niobium, tantalum, boron, nitrogen and calcium.
  • oxygen oxygen
  • phosphorus phosphorus
  • sulphur sulphur
  • the content thereof should generally not exceed 0.05 wt.%.
  • the phosphorus content will be about 0.004 wt.%.
  • sulphur is present, the content should generally not exceed 0.05 wt.%.
  • the sulphur content will be about 0.003 wt.%.
  • oxygen is present, the content should generally not exceed 0.1 wt.%.
  • the oxygen content does not exceed 0.01 wt.%, more preferably, the oxygen content does not exceed 50 ppm.
  • the steel for use in the bearing component according to the present invention may contain unavoidable impurities although, in total, these are unlikely to exceed 0.5 wt.% of the composition.
  • the alloys contain unavoidable impurities in an amount of not more than 0.3 wt.% of the composition, more preferably not more than 0.1 wt.% of the composition.
  • the content of these three elements is preferably kept to a minimum.
  • the alloys according to the present invention may consist essentially of the recited elements. It will therefore be appreciated that in addition to those elements which are mandatory other non-specified elements may be present in the composition provided that the essential characteristics of the composition are not materially affected by their presence.
  • the steel alloy preferably has a microstructure comprising a tempered martensitic matrix within which carbides and/or carbonitrides, typically vanadium carbide precipitates, are embedded.
  • a microstructure results in the favourable mechanical properties of the steel alloy, in particular high hardness.
  • the microstructure may typically comprise up to 20 vol.% carbides, more typically from 15 to 19 vol. % carbides, for example about 17 vol. % carbides.
  • the steel alloy is preferably formed by a powder metallurgical technique. Such a technique may enable the production of a highly alloyed steel with higher hardness and strength after secondary hardening operations, in particular a steel having a microstructure comprising fine vanadium carbide precipitates. Accordingly, this route is advantageous for high load bearing applications.
  • Suitable powder metallurgical techniques include, for example, vacuum induction melting (e.g. by the technique of Crucible Compaction Metals - CPM) or electro slag processes (e.g. the ASEA Stora Process - ASP
  • the steel alloy typically has a strength of at least 60 HRC, preferably at least 65 HRC. Such a strength may enable the alloy to be effectively used in a bearing component, in particular a bearing component operating in a high load environment.
  • the present invention provides a bearing component comprising the steel alloy as described herein.
  • the bearing component may be at least one of a rolling element (for example, ball or roller), an inner ring, and an outer ring.
  • the bearing component could also be part of a linear bearing such as ball and roller screws.
  • the present invention provides a bearing comprising the bearing component as described herein.
  • the present invention provides a process for manufacturing the steel alloy as described herein, the process comprising:
  • the process can be used to manufacture the steel alloy described herein.
  • Powder metallurgy typically relies on a forming and fabrication technique comprising three major processing stages:-
  • Powdering the material to be handled is physically powdered and divided into many small individual particles.
  • Moulding the powder is injected into a mould or passed through a die to produce a weakly cohesive structure close in dimension to the desired product.
  • the moulded article is subjected to compression and optionally high temperature to form the final article.
  • compression the moulded article is subjected to compression and optionally high temperature to form the final article.
  • powder metallurgical steps is conventional in the art.
  • the powder metallurgical technique comprises the steps of gas powder atomization of the bearing steel composition, followed by hot-isotactic pressing.
  • the gas powder atomization preferably uses an inert gas (for example, a gas comprising or consisting of nitrogen) in a closed system, so that contamination of the powder is reduced.
  • composition used in the process preferably corresponds to the composition of the final article produced. However, while the weight percentage of most of the elements will remain essentially constant, any nitrogen content may decrease slightly, perhaps due to degassing.
  • the present invention provides a method of forming the bearing component as described herein, the method comprising:
  • the temperature of step (II) is preferably from 825 to 925 °C, more preferably from 850 to 900 °C, even more preferably at about 875 °C. Such temperatures are typically just above a temperature at which all the ferrite is dissolved, and the alloy is typically maintained at such temperatures for a sufficient time to form austenite and a small amount of undissolved carbides.
  • Step (II) may further comprise slow cooling to a temperature of from 650 to 720 °C, preferably from 670 to 690 °C, over a period of from 1 to 4 hours, preferably from 2 to 3 hours. Such slow cooling may result in the divorced pearlite reaction occurring. The alloy may then be cooled to room temperature.
  • Step (IV) preferably comprises:
  • step (C) carrying out a tempering heat-treatment.
  • the composition is at least partially austenitised, preferably completely austenitised, with some retained undissolved carbides. This is achieved by heating the alloy composition to a temperature of from 1050 to 1200 °C, preferably from 1 100 to 1 160 °C, more preferably from 1 120 to 1 140 °C, and most preferably about 1 130 °C. The composition may be maintained in this temperature regime for up to about 10 minutes.
  • Step (B) may result in the retention of vanadium carbides.
  • the method may further comprise a vacuum hardening pre-heating step prior to step (IV).
  • the pre-heating step may comprise, for example:
  • heating to a temperature of from 1050 to 1 100 °C (typically about 1080 ⁇ €).
  • Heating to a temperature of from 1050 to 1 100 °C is typically carried out at a rate of from 1 to 10 °C per minute, more typically about 5 ⁇ per minute.
  • the steel alloy is typically cleaned and degreased prior to the pre-heating step.
  • the pre-heating step may be carried out using a conventional furnace.
  • the steel alloy is preferably inserted into the furnace at a temperature of 250 °C or less.
  • the pre-heating step may increase the hardness of the steel alloy, which may be advantageous when the steel alloy is used in a bearing component.
  • Step (B) preferably comprises gas quenching using, for example nitrogen gas, with pressure of from 6 to 8 bar.
  • the quenching is preferably carried out to a temperature of from 40 to 50 °C.
  • the cooling rate during quenching is sufficiently fast such that the formation of grain boundary carbides may be prevented.
  • Step (C) may advantageously keep the reduced austenite content of the steel alloy to a minimum.
  • Step (C) preferably comprises:
  • the tempering is preferably carried out in a vacuum or inert atmosphere.
  • the tempering is preferably carried out for from 1 to 3 hours. Longer tempering times may be employed.
  • the tempering is preferably carried out at a temperature of from 530 °C to 580 °C, more preferably about 530 °C.
  • the alloy is preferably quenched to a temperature of from -220 to -150 °C, preferably about -196 °C, in between the tempers.
  • the quenching may be carried out using, for example, liquid nitrogen.
  • fast cooling is carried out, for example by the use of liquid nitrogen, the alloy is preferably cooled more slowly to room temperature prior to fast cooling.
  • Step (C) is preferably carried out from 2 to 4 times, more preferably 3 or 4 times.
  • Figure 1 shows a scanning electron microscope image of a steel alloy according to the present invention prior to spheroidisation.
  • Figure 2 shows a plot of the spheroidisation treatment of Example 1 .
  • Figure 3 shows a scanning electron microscope image of a steel alloy according to the present invention after spheroidisation.
  • Figure 4 shows a scanning electron microscope image of a steel alloy according to the present invention after final heat treatment.
  • Table 1 The chemical composition of the PM steel, in wt.%. The balance is iron and unavoidable impurities.
  • the steel structure in the hot-isostatic pressed condition featured a martensitic matrix. This is shown in Figure 1 .
  • the following spheroidisation treatment was carried out on the steel: heating the steel alloy to about 875 °C over a period of about 2 hours; holding the steel at about 875 °C for a period of about 1 .5 hours; cooling the steel to a temperature of about 680 °C over a period of about 2.5 hours; and quenching the steel to room temperature.
  • the steel was cleaned and degreased before carrying out the following hardening heat treatment: vacuum hardening with pre-heating (in 3 steps at: 600 e C and equalise, then at 800 e C and equalise, then increase the temperature to 1080 e C in about 56 minutes (the heating rate between 800 e C and 1080 e C was ⁇ 5 e C/min)); austenitisation at 1 130 e C +/- 5 e C for 10 minutes at temperature; gas quench with nitrogen pressure 6 to 8 bars (transfer time to the quench chamber kept to a minimum - cool down to 40-50 e C); temper immediately at 560 e C x 1 hour minimum at temperature in vacuum; cool to room temperature (25 e C); deep freeze to liquid nitrogen temperature (time at temperature was 1 hour); temper at 560 e C x 1 hour minimum at temperature in vacuum; cool to room temperature (25 e C); deep freeze to liquid nitrogen temperature (time at temperature was 1 hour); temper at 560 e C x 1 hour minimum at temperature in vacuum; cool
  • the steel alloy exhibited the microstructure shown in Figure 4.
  • the microstructure comprised a tempered martensitic matrix within which vanadium carbide precipitates (approximately 16.8 % by area) are embedded.
  • the heat-treated steel alloy exhibited a high Rockwell hardness of 65.2 HRC with a standard deviation of ⁇ 0.04 (average of six measurements).

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Rolling Contact Bearings (AREA)

Abstract

L'invention concerne un alliage d'acier sans cobalt qui comprend : (a) 2 à 3 % en poids de carbone, (b) 4 à 6 % en poids de chrome, (c) 0,1 à 0,5 % en poids de manganèse, (d) 0,1 à 0,9 % en poids de silicium, (e) 9 à 11 % en poids de molybdène, (f) 6 à 8 % en poids de vanadium, (g) éventuellement un ou plusieurs des éléments suivants : 0 à 0,3 % en poids de cuivre, 0 à 0,2 % en poids de nickel, 0 à 0,1 % en poids d'aluminium, 0 à 0,05 % en poids de phosphore, 0 à 0,05 % en poids de soufre, 0 à 0,1 % en poids de titane, 0 à 0,1 % en poids de niobium, 0 à 0,1 % en poids de tantale, 0 à 0,1 % en poids de bore, 0 à 0,1 % en poids d'azote, 0 à 0,1 % en poids d'oxygène, 0 à 0,1 % en poids de calcium, 0 à 0,1 % en poids de tungstène, (h) le reste étant du fer, et des impuretés inévitables.
PCT/EP2014/071440 2014-10-07 2014-10-07 Alliage d'acier WO2016055098A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE112014007041.6T DE112014007041T5 (de) 2014-10-07 2014-10-07 Stahllegierung
PCT/EP2014/071440 WO2016055098A1 (fr) 2014-10-07 2014-10-07 Alliage d'acier

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2014/071440 WO2016055098A1 (fr) 2014-10-07 2014-10-07 Alliage d'acier

Publications (1)

Publication Number Publication Date
WO2016055098A1 true WO2016055098A1 (fr) 2016-04-14

Family

ID=51688052

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2014/071440 WO2016055098A1 (fr) 2014-10-07 2014-10-07 Alliage d'acier

Country Status (2)

Country Link
DE (1) DE112014007041T5 (fr)
WO (1) WO2016055098A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108247288A (zh) * 2017-12-18 2018-07-06 贵州航宇科技发展股份有限公司 一种Ti6242钛合金薄壁环件的加工制造方法
WO2020149787A1 (fr) * 2019-01-18 2020-07-23 Vbn Components Ab Acier à haute teneur en carbone imprimé en 3d et son procédé de préparation
CN114959437A (zh) * 2022-05-31 2022-08-30 广东省科学院新材料研究所 一种钒合金化高铬铸铁及其制备方法和应用
US20240110265A1 (en) * 2022-10-04 2024-04-04 Hyundai Motor Company Sintered material for aluminum die casting and manufacturing method thereof

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4276087A (en) * 1979-05-03 1981-06-30 Crucible Inc. Powder-metallurgy vanadium-containing tungsten-type high-speed steel
JPH02232338A (ja) * 1989-03-03 1990-09-14 Kubota Ltd 耐摩耗性に優れたロール材
JPH05271867A (ja) * 1992-03-30 1993-10-19 Hitachi Metals Ltd 圧延用ロール材
JPH06240418A (ja) * 1992-12-21 1994-08-30 Daido Steel Co Ltd 熱間圧延用焼結ロールおよびその製造方法
JPH08199311A (ja) * 1995-01-20 1996-08-06 Nippon Steel Corp 高耐焼付性熱間圧延用ロール材
JPH0999306A (ja) * 1995-10-06 1997-04-15 Hitachi Metals Ltd 熱間圧延用ロール
RU2102519C1 (ru) * 1995-08-15 1998-01-20 Акционерное общество "Брянский машиностроительный завод" Инструментальный сплав
JP2000288708A (ja) * 1999-04-01 2000-10-17 Nippon Steel Corp 圧延用スリーブロール

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4276087A (en) * 1979-05-03 1981-06-30 Crucible Inc. Powder-metallurgy vanadium-containing tungsten-type high-speed steel
JPH02232338A (ja) * 1989-03-03 1990-09-14 Kubota Ltd 耐摩耗性に優れたロール材
JPH05271867A (ja) * 1992-03-30 1993-10-19 Hitachi Metals Ltd 圧延用ロール材
JPH06240418A (ja) * 1992-12-21 1994-08-30 Daido Steel Co Ltd 熱間圧延用焼結ロールおよびその製造方法
JPH08199311A (ja) * 1995-01-20 1996-08-06 Nippon Steel Corp 高耐焼付性熱間圧延用ロール材
RU2102519C1 (ru) * 1995-08-15 1998-01-20 Акционерное общество "Брянский машиностроительный завод" Инструментальный сплав
JPH0999306A (ja) * 1995-10-06 1997-04-15 Hitachi Metals Ltd 熱間圧延用ロール
JP2000288708A (ja) * 1999-04-01 2000-10-17 Nippon Steel Corp 圧延用スリーブロール

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108247288A (zh) * 2017-12-18 2018-07-06 贵州航宇科技发展股份有限公司 一种Ti6242钛合金薄壁环件的加工制造方法
WO2020149787A1 (fr) * 2019-01-18 2020-07-23 Vbn Components Ab Acier à haute teneur en carbone imprimé en 3d et son procédé de préparation
CN113260473A (zh) * 2019-01-18 2021-08-13 Vbn组件有限公司 3d打印的高碳含量钢及其制备方法
CN113260473B (zh) * 2019-01-18 2023-09-19 Vbn组件有限公司 3d打印的高碳含量钢及其制备方法
CN114959437A (zh) * 2022-05-31 2022-08-30 广东省科学院新材料研究所 一种钒合金化高铬铸铁及其制备方法和应用
US20240110265A1 (en) * 2022-10-04 2024-04-04 Hyundai Motor Company Sintered material for aluminum die casting and manufacturing method thereof

Also Published As

Publication number Publication date
DE112014007041T5 (de) 2017-09-14

Similar Documents

Publication Publication Date Title
US11078559B2 (en) Rolling element bearing having bainite microstructure
US10865457B2 (en) Steel composition
CA3078221A1 (fr) Acier inoxydable, poudre pre-alliee obtenue par atomisation de cet acier et utilisation de cette poudre pre-alliee
JP6471914B2 (ja) 鋼合金およびそのような鋼合金を含む部品、鋼合金の製造方法
CN113718174B (zh) 一种双细化高强韧长寿命中高碳轴承钢及制备方法
GB2535782A (en) Bearing Steel
CN107034422A (zh) 耐疲劳轴承钢
GB2527387A (en) Bearing steel composition
US20200190638A1 (en) Powder-Metallurgically Produced Steel Material Containing Hard Material Particles, Method for Producing a Component from Such a Steel Material, and Component Produced from the Steel Material
WO2016055098A1 (fr) Alliage d'acier
CN113913679A (zh) 冷加工工具钢
CN110699610B (zh) 钢合金
US9758849B2 (en) Bearing steel composition
US20150023623A1 (en) Bearing component
WO2016083283A1 (fr) Composant de palier
GB2513881A (en) Steel Alloy
US20160076591A1 (en) Bearing component
EP2814994B1 (fr) Composition d'acier à coussinets
WO2014053385A1 (fr) Alliage d'acier
EP2771495B1 (fr) Composant porteur
WO2015110366A1 (fr) Acier pour roulement

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 14781868

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 112014007041

Country of ref document: DE

122 Ep: pct application non-entry in european phase

Ref document number: 14781868

Country of ref document: EP

Kind code of ref document: A1