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EP0203050A1 - Procédé de fabrication d'une fonte à graphite spréroidal, trempée et bainitique - Google Patents

Procédé de fabrication d'une fonte à graphite spréroidal, trempée et bainitique Download PDF

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Publication number
EP0203050A1
EP0203050A1 EP86850178A EP86850178A EP0203050A1 EP 0203050 A1 EP0203050 A1 EP 0203050A1 EP 86850178 A EP86850178 A EP 86850178A EP 86850178 A EP86850178 A EP 86850178A EP 0203050 A1 EP0203050 A1 EP 0203050A1
Authority
EP
European Patent Office
Prior art keywords
austenite
temperature
ferrite
bainite
iron
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.)
Withdrawn
Application number
EP86850178A
Other languages
German (de)
English (en)
Inventor
Sven-Eric Stenfors
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.)
Volvo AB
Original Assignee
Volvo 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 Volvo AB filed Critical Volvo AB
Publication of EP0203050A1 publication Critical patent/EP0203050A1/fr
Withdrawn legal-status Critical Current

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    • 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
    • C21D5/00—Heat treatments of cast-iron

Definitions

  • the present invention relates to a method for manufacturing a novel material of the spheroidal graphite iron kind possessing good mechanical strength and working properties.
  • Spheroidal graphite iron thus possesses good qualities, which can be further improved by hardening. Consequently, attention has been directed towards the possibility of hardening spheroidal graphite iron in a manner to obtain a phase having a bainite structure.
  • Bainite comprises a mixture of ferrite and cementite. Austempering to a bainite structure is effected by subjecting a casting having a ferritic and perlitic basic structure to an austenitic process (austenitization). The material is then cooled rapidly to a point above the martensite point (M S), whereafter the austenite is converted isothermally to bainite. There is normally obtained an austenite residue of from 10-50%, which is considered to have a favourable effect on the mechanical properties.
  • Spheroidal graphite iron which has been austempered is used, for example, in the gears of vehicle engines, and experiments are being made with the use of austempered spheroidal graphite iron in the crank shafts of petrol driven engines, where it has previously been necessary to forge the crank shafts.
  • a bainite structure can also be obtained, of course, by regulating the cooling process during a casting operation in a manner which enables a bainite structure to be obtained.
  • austempering is effected by austenitization, to obtain smoother carbon distribution and an adapted carbon content in the basic material, i.e. material between and at a given distance from the precipitated nodular graphite.
  • the cast austenitized component is then rapidly cooled to a temperature above the martensite conversion M .
  • the component is then maintained at this temperature for a period of time sufficient to permit total and partial isothermic conversion of the basic mass to bainite in a suitable medium.
  • the formation of bainite can be controlled by suitable determination of the carbon content and the soaking temperature.
  • the spheroidal graphite iron casting is allowed to cool in air, wherewith a part of the residual austenite will convert to martensite.
  • the basic material then consists of bainite, residual austenite, and with short soaking times martensite.
  • Austenitization is preferably effected in a salt bath or furnaces, and the isothermic conversion normally in a salt bath, and at lower temperatures in an oil bath.
  • the conversion to bainite is effected in two stages, in which there is first precipitated ferrite as Widmanstatten ferrite at not too low temperatures, whereafter cementite and ferrite is precipitated therebetween.
  • the formation of ferrite causes the carbon content of the residual austenite to increase.
  • Silicon has a delaying effect on the bainite conversion, which first results in a constant residual austenite content, which is then converted to bainite at longer isothermic conversion times.
  • the time taken to obtain a bainite structure can be reduced by lowering the silicon content, although a certain amount of silicon is required to obtain solidification to grey iron.
  • a ferrite-bainite cast iron with spheroidal graphite is produced by austenizing at a temperature such that the material comprises a mixture of ferrite and austenite after the austenitization process.
  • a spheroidal graphite iron is produced by smelting an iron alloy containing 3.0-3.6% carbon, 3.5-5.0 % silicon, 0.7-5.0% nickel, 0-0.3% molybdenum, 0.2-0.4% manganese, less than 0.015% sulphur and 0.06% phosphorus, the resultant molten bath being allowed to cool in the presence of a nodulizing agent.
  • the solidified cast iron is then heated to a temperature of 855-900°C for 1-3 hours, whereafter the bath is cooled with an effect of at least 152°C min -1 to 205-400°C and is held at this-temperature for 0.5-4 hours, whereafter it is cooled to room temperature. It is evident from the patent specification that a ferrite-bainite structure was not obtained when the silicon content was below 4% or the nickel content below 0.7%, or when the isothermic treatment exceeded or fell short of the stipulated time interval.
  • an austempered spheroidal graphite iron having a microstructure of bainite, ferrite, and residual austenite although with negligible martensite content, and possessing extremely good working properties and extremely good strength properties, which enable austempered spheroidal graphite iron to be utilized economically as a material for the manufacture of machine and engine components, such as gears and crank shafts, with respect to both mechanical strength and economic manufacturability.
  • austenitized a cast product manufactured from an iron alloy containing 2-3.5% silicon, 0.2% manganese, 0-5% nickel, 0-0.3% tin, 0-0.3% chromium, 0-3% molybdenum, 0-1.5% copper, 3.3-3.8 ⁇ carbon, and at most 0.08% phosphorus and 0.015% sulphur, partly by heat treating the casting at a temperature beneath the level at which austenite and graphite, or just austenite are in equilibrium, but within the temperature range in which ferrite, austenite and graphite are in equilibrium, and then rapidly lowering the temperature of the casting by at least 100 Kmin -1 , and thereafter holding the casting at a constant temperature for 0.5 to 4 hours, this tempperature being between 235 and 4250C, wherewith part of the austenite formed is converted to bainite, to provide a casting containing a bainite structure with a residual austenite content of 5-40% and a ferrite content of 10-50%.
  • Figure 1 is an iron-carbon diagram of an alloy containing 2.7% silicon and 0.2% manganese.
  • the sign ⁇ represents ferrite and the sign austenite. It will be seen from the diagram that an area is formed in which ferrite, austenite and graphite are in equilibrium within an area corresponding to the line A, in the iron-carbon diagram.
  • the magnitude and precise location of this three-phase area varies with the composition of the iron, and silicon and the manganese content are therewith of particular significance.
  • the existence of this area is well known to those skilled in this art, although the realization of its significance when austempering spheroidal graphite iron, to obtain a bainite structure, is an important contribution to the art. It is possible with knowledge of Gibbs free energies to calculate thermodynamically the location of the three-phase area for a given composition.
  • a higher silicon content results in a broader three-phase area, and hence the silicon content suitably lies within 2.7-4.5% by weight, preferably within 3.0-3.6%.
  • the higher silicon contents render the material more difficult to machine or cut, due to solution annealing of the ferrite present.
  • the manganese content increases the three-phase area and, in accordance with the invention, is preferably held between 0 and 2%.
  • the temperature of the casting is lowered at a rate corresponding to at least 100 K min-l, and is thereafter held at a constant temperature of between 285 and 425 0 C for sufficient length of time for part of the austenite formed to convert to bainite, therewith providing a casting which incorporates a bainite structure with a residual austenite content of 5-40%, preferably 15-20%, and a ferrite content of 10-50%, preferably 20-40%.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
EP86850178A 1985-05-22 1986-05-20 Procédé de fabrication d'une fonte à graphite spréroidal, trempée et bainitique Withdrawn EP0203050A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8502514 1985-05-22
SE8502514A SE8502514L (sv) 1985-05-22 1985-05-22 Forfarande for framstellning av ett bainitherdat segjern

Publications (1)

Publication Number Publication Date
EP0203050A1 true EP0203050A1 (fr) 1986-11-26

Family

ID=20360299

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86850178A Withdrawn EP0203050A1 (fr) 1985-05-22 1986-05-20 Procédé de fabrication d'une fonte à graphite spréroidal, trempée et bainitique

Country Status (4)

Country Link
EP (1) EP0203050A1 (fr)
FI (1) FI862137A7 (fr)
PT (1) PT82629B (fr)
SE (1) SE8502514L (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4867804A (en) * 1986-12-26 1989-09-19 Kurimoto Ltd. Manufacturing process of toughened bainitic nodular graphite cast iron
AU615125B2 (en) * 1988-12-13 1991-09-19 Sandvik Ab Roll ring, comprising cemented carbide and cast iron, and method for manufacture of the same.
EP0639651A1 (fr) * 1993-08-18 1995-02-22 Centre Technique Des Industries De La Fonderie Procédé de traitement intercritique de charges en fonte
FR2712606A1 (fr) * 1993-11-19 1995-05-24 Tech Ind Fonderie Centre Procédé d'élaboration d'une charge de fonte à graphite sphéroïdal à caractéristiques mécaniques élevées.
WO1999014382A1 (fr) * 1997-09-16 1999-03-25 Weyburn-Bartel Inc. Pieces en fonte
WO2008076067A1 (fr) * 2006-12-16 2008-06-26 Indexator Ab Procédé de fabrication d'au moins une partie d'un dispositif destiné à un engin de terrassement ou à un engin servant à manipuler des matériaux, faisant intervenir de la fonte ductile ayant subie une trempe étagée bainitique
CN1789465B (zh) * 2004-12-17 2012-02-01 通用电气公司 球墨铸铁合金和由其形成的涡轮机压缩机外壳元件
CN104152787A (zh) * 2014-07-25 2014-11-19 安徽省宁国诚信耐磨材料有限公司 一种球墨铸球及其制作方法
CN106756464A (zh) * 2016-12-27 2017-05-31 宁国市华丰耐磨材料有限公司 一种大尺径奥铁体球墨铸铁磨球的制备方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114231830A (zh) * 2021-11-05 2022-03-25 宁国东方碾磨材料股份有限公司 一种球墨铸铁磨球及其制备方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0018445A1 (fr) * 1978-12-13 1980-11-12 Horst Dr. Mühlberger Procédé pour la fabrication de pièces coulée en fonte nodulaire
EP0144907A2 (fr) * 1983-12-05 1985-06-19 Nissan Motor Co., Ltd. Procédé pour la fabrication de pièces de fonte à graphite sphéroidal par trempe bainitique

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0018445A1 (fr) * 1978-12-13 1980-11-12 Horst Dr. Mühlberger Procédé pour la fabrication de pièces coulée en fonte nodulaire
EP0144907A2 (fr) * 1983-12-05 1985-06-19 Nissan Motor Co., Ltd. Procédé pour la fabrication de pièces de fonte à graphite sphéroidal par trempe bainitique

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4867804A (en) * 1986-12-26 1989-09-19 Kurimoto Ltd. Manufacturing process of toughened bainitic nodular graphite cast iron
AU615125B2 (en) * 1988-12-13 1991-09-19 Sandvik Ab Roll ring, comprising cemented carbide and cast iron, and method for manufacture of the same.
EP0639651A1 (fr) * 1993-08-18 1995-02-22 Centre Technique Des Industries De La Fonderie Procédé de traitement intercritique de charges en fonte
FR2709133A1 (fr) * 1993-08-18 1995-02-24 Tech Ind Fonderie Centre Procédé de traitement intercritique de charges en fonte.
FR2712606A1 (fr) * 1993-11-19 1995-05-24 Tech Ind Fonderie Centre Procédé d'élaboration d'une charge de fonte à graphite sphéroïdal à caractéristiques mécaniques élevées.
WO1999014382A1 (fr) * 1997-09-16 1999-03-25 Weyburn-Bartel Inc. Pieces en fonte
CN1789465B (zh) * 2004-12-17 2012-02-01 通用电气公司 球墨铸铁合金和由其形成的涡轮机压缩机外壳元件
WO2008076067A1 (fr) * 2006-12-16 2008-06-26 Indexator Ab Procédé de fabrication d'au moins une partie d'un dispositif destiné à un engin de terrassement ou à un engin servant à manipuler des matériaux, faisant intervenir de la fonte ductile ayant subie une trempe étagée bainitique
WO2008076051A1 (fr) * 2006-12-16 2008-06-26 Indexator Ab Fonte ductile ayant subie une trempe étagée bainitique, procédé de production de cette fonte et composant comprenant cette fonte
US8192561B2 (en) 2006-12-16 2012-06-05 Indexator Group Ab Method for manufacturing at least part of a device for an earthmoving or materials-handling machine using austempered ductile iron and its named product
US8858736B2 (en) 2006-12-16 2014-10-14 Indexator Group Ab Austempered ductile iron, method for producing this and component comprising this iron
CN104152787A (zh) * 2014-07-25 2014-11-19 安徽省宁国诚信耐磨材料有限公司 一种球墨铸球及其制作方法
CN104152787B (zh) * 2014-07-25 2017-01-11 安徽省宁国诚信耐磨材料有限公司 一种球墨铸球及其制作方法
CN106756464A (zh) * 2016-12-27 2017-05-31 宁国市华丰耐磨材料有限公司 一种大尺径奥铁体球墨铸铁磨球的制备方法

Also Published As

Publication number Publication date
PT82629A (en) 1986-06-01
PT82629B (en) 1987-09-28
SE8502514L (sv) 1986-11-23
SE8502514D0 (sv) 1985-05-22
FI862137A0 (fi) 1986-05-21
FI862137A7 (fi) 1986-11-23

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