EP0586179A1 - Pièce forgée et procédé pour sa fabrication - Google Patents

Pièce forgée et procédé pour sa fabrication Download PDF

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Publication number
EP0586179A1
EP0586179A1 EP93306710A EP93306710A EP0586179A1 EP 0586179 A1 EP0586179 A1 EP 0586179A1 EP 93306710 A EP93306710 A EP 93306710A EP 93306710 A EP93306710 A EP 93306710A EP 0586179 A1 EP0586179 A1 EP 0586179A1
Authority
EP
European Patent Office
Prior art keywords
percent
weight
forging
billet
quenching
Prior art date
Legal status (The legal status 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 status listed.)
Granted
Application number
EP93306710A
Other languages
German (de)
English (en)
Other versions
EP0586179B1 (fr
Inventor
Vesa Ollilainen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ovako Bar Oy
Original Assignee
Imatra Steel Oy AB
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 Imatra Steel Oy AB filed Critical Imatra Steel Oy AB
Publication of EP0586179A1 publication Critical patent/EP0586179A1/fr
Application granted granted Critical
Publication of EP0586179B1 publication Critical patent/EP0586179B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
    • 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
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
    • 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
    • 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
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/60—Aqueous agents

Definitions

  • the invention relates to an improved forging with favourable strength features and toughness and a method of manufacturing the forging.
  • Raising the carbon content increases the strength effectively, but high contents, especially contents substantially over 0.1%, impair toughness and machinability.
  • Raising the manganese content to more than 1% is in many cases useful, but manganese has a strong tendency to segregation. This easily causes quite large strength variations over the cross-section of a component and between components in continuous production. In addition, the segregation of manganese impairs the machinability of the steel.
  • chromium has a low tendency to segregation, so that not even contents above 1% impair machinability.
  • an improvement of the known technique is achieved by adding small amounts of molybdenum, so that the molybdenum content is 0.04 to 0.25 percent by weight, preferably 0.04 to 0.15 percent by weight.
  • the present invention therefore provides a forging with favourable strength features and toughness, characterised in that it is produced of a material, which in addition to iron and incidental impurities has the following material contents in percent by weight
  • the invention also provides a method for producing an improved forging with favourable strength features and toughness, characterised in that the billet for the desired improved forging is produced of a material which in addition to iron and incidental impurities consists of the following elements:
  • a new alloying element By alloying a steel according to the invention with molybdenum the strength can be raised effectively at low contents. This is caused by the high hardenability factor of molybdenum, especially when the carbon content is low, as in the invention. Further, the introduction of a new alloying element has a synergistic effect on hardenability, in other words, a new alloying element improves hardenability more effectively when employed together with other alloying elements (in this case manganese and chromium) than when employed alone.
  • Molybdenum also favours the formation of bainite, which can be seen, for example, in a so-called CCT-diagram as a wide area of bainite.
  • the wide bainite area minimises the strength difference between the surface and the core, because the formation of martensite on the surface can be prevented, which results in that the component becomes practically fully bainitic.
  • a wide bainite area means in practice that the quenching rate used is not very critical, so that quite a wide range of quenching rates may be used. In quenching large cross-section components the quenching rate is by necessity relatively low, but this does not cause any essential disadvantages when applying the invention.
  • molybdenum does not impair toughness but improves it.
  • the relatively high price of molybdenum restricts its economical use to low contents.
  • molybdenum is a considerably cheaper alloying element than for instance nickel.
  • the molybdenum content is at the most 0.25 percent by weight and a preferred content is at the most 0.15 percent by weight, whereby the synergistic effect of molybdenum on hardenability is at its peak. At increasing contents of molybdenum its effect on hardenability per content unit decreases.
  • a quenching technique can be used for minimising non-uniformity in strength.
  • a forging in water or in a water-based (polymer) emulsion or solution sufficiently uniform strength properties over the cross-section of the component are normally obtained when using a steel according to the invention.
  • Water is usually the most desirable quenching fluid.
  • Other substances may be added to the water so that a water-based emulsion or solution is formed. This has an influence on the quenching effect of the water.
  • the quenching effect of water may also be influenced by controlling its temperature. By raising the water temperature over room temperature, preferably to a temperature of over 30°C or 40°C, the best results are usually obtained.
  • Another recommendable quenching technique, when applying the invention, is spray quenching, because its adjustability is outstanding. The effect of spray quenching can easily be adjusted and the quenching can be directed to only a part of a component. Thereby only the desired portion of the component becomes hardened, while the other portions remain soft and tough.
  • a particularly preferred steel according to the invention consists in addition to iron (and incidental impurities) the following contents of other elements, in percent by weight: C 0.06%, Si 0.28%, Mn 0.91%, S 0.080%, Cr 1.11%, Al 0.038%, Mo 0.10%, Ti 0.019%, B 0.005%.
  • a steel billet according to the invention is well suited not only as a directly quenched hot forging billet, but also for cold forming either rapidly annealed or directly hot-rolled without annealing.
  • a steel according to the invention is also well suited for nitriding or nitrocarburising.
  • Molybdenum improves the resistance to softening during tempering, which improves the core strength at nitriding.
  • molybdenum has an effect on preventing temper embrittlement, which improves the toughness, in particular if the component is nitrided.
  • Forging billets according to the invention may be cold cropped from continuous cast or hot-rolled steel bars and the finished forging may be directly quenched from the forging temperature. Forgings according to the invention may be machined and used without tempering.
  • Forgings may be assembled also by fusion welding of several component parts.
  • a steel according to the invention is very well suited also for carburising hardening.
  • the advantage is then that core elongation and toughness exceed normal values, which is caused by the lower than usual carbon content of the steel. This allows the use of the steel in particular in such carburising hardened elements in which large deformations occur and which for that reason must be straightened, for example by cold-straightening.
  • the strength and toughness of a component according to the invention can be improved by controlling relatively carefully the end temperature of the hot forging.
  • the most preferred end temperature of the forging is 950°C to 1050°C.
  • Another way of increasing the strength is to avoid very low carbon contents. It is recommended that the carbon content is at least 0.07 percent by weight/ In general terms the carbon content should preferably, within the limits of the invention, be sufficiently high that the tensile strength of the finished forging is, without tempering, at least 900 N/mm2.
  • the machinability of the steel can be improved quite significantly.
  • the sulphur content should not be more than 0.15 percent by weight, above which value the mechanical properties are impaired.
  • the invention is also illustrated in the accompanying drawing which is a CCT-diagram showing the structure of a forging according to the invention (preferred composition) at different quenching rates.
  • the horizontal axis of the diagram shows the time in seconds and the vertical axis the temperature in degrees centigrade.
  • the martensite area is indicated by the letter M, the bainite area by the letter B, the ferrite area by the letter F and the perlite area by the letter P.
  • the areas have been determined by using different heating temperatures of test samples.
  • the set of curves shown in full lines reflects the situation when the heating has been to 1200°C, the broken line curves show heating to 900°C and dotted line curves show heating to 1200°C as well as forming of the test sample by upsetting to 50 percent area reduction.
EP93306710A 1992-09-02 1993-08-24 Pièce forgée et procédé pour sa fabrication Expired - Lifetime EP0586179B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI923929A FI95049C (fi) 1992-09-02 1992-09-02 Parannettu takokappale ja sen valmistusmenetelmä
FI923929 1992-09-02

Publications (2)

Publication Number Publication Date
EP0586179A1 true EP0586179A1 (fr) 1994-03-09
EP0586179B1 EP0586179B1 (fr) 1998-11-11

Family

ID=8535802

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93306710A Expired - Lifetime EP0586179B1 (fr) 1992-09-02 1993-08-24 Pièce forgée et procédé pour sa fabrication

Country Status (3)

Country Link
EP (1) EP0586179B1 (fr)
DE (1) DE69322028T2 (fr)
FI (1) FI95049C (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008037327A1 (fr) * 2006-09-28 2008-04-03 Rothe Erde Gmbh procédé de traitement thermomécanique d'anneaux fabriqués sans cordon sur des machines de laminage radial-axial d'anneaux
CN111057933A (zh) * 2019-12-17 2020-04-24 安徽旭通网络科技有限公司 一种高性能压铸模用热作模具钢的制造工艺

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE749477C (de) * 1941-12-23 1953-03-23 Edelstahlwerke A G Krefeld Deu Stahl mit hohem Widerstand gegen schlagartige Beanspruchung
DE927213C (de) * 1942-08-12 1955-05-02 Oberhuetten Vereinigte Obersch Aus Baustaehlen bestehende Gegenstaende
US3348981A (en) * 1964-02-21 1967-10-24 Yawata Iron & Steel Co High tension low temperature tough steel
US4711676A (en) * 1985-05-17 1987-12-08 Tsubakimoto Chain Company Carburized pin for chain

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE749477C (de) * 1941-12-23 1953-03-23 Edelstahlwerke A G Krefeld Deu Stahl mit hohem Widerstand gegen schlagartige Beanspruchung
DE927213C (de) * 1942-08-12 1955-05-02 Oberhuetten Vereinigte Obersch Aus Baustaehlen bestehende Gegenstaende
US3348981A (en) * 1964-02-21 1967-10-24 Yawata Iron & Steel Co High tension low temperature tough steel
US4711676A (en) * 1985-05-17 1987-12-08 Tsubakimoto Chain Company Carburized pin for chain

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008037327A1 (fr) * 2006-09-28 2008-04-03 Rothe Erde Gmbh procédé de traitement thermomécanique d'anneaux fabriqués sans cordon sur des machines de laminage radial-axial d'anneaux
CN101506391B (zh) * 2006-09-28 2011-09-14 罗兹埃德公司 无缝地在径向轴向环轧机上制造的环的热机械处理方法
US8377238B2 (en) 2006-09-28 2013-02-19 Rothe Erde Gmbh Method for the thermomechanical treatment of seamless rings produced on radial-axial ring rolling machines
CN111057933A (zh) * 2019-12-17 2020-04-24 安徽旭通网络科技有限公司 一种高性能压铸模用热作模具钢的制造工艺

Also Published As

Publication number Publication date
FI923929A0 (fi) 1992-09-02
EP0586179B1 (fr) 1998-11-11
FI923929A (fi) 1994-03-03
DE69322028T2 (de) 1999-04-01
DE69322028D1 (de) 1998-12-17
FI95049B (fi) 1995-08-31
FI95049C (fi) 1995-12-11

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