EP0271688A1 - Procédé pour la fabrication de pièces moulées en fonte bainitique modulaire - Google Patents

Procédé pour la fabrication de pièces moulées en fonte bainitique modulaire Download PDF

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Publication number
EP0271688A1
EP0271688A1 EP87116105A EP87116105A EP0271688A1 EP 0271688 A1 EP0271688 A1 EP 0271688A1 EP 87116105 A EP87116105 A EP 87116105A EP 87116105 A EP87116105 A EP 87116105A EP 0271688 A1 EP0271688 A1 EP 0271688A1
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EP
European Patent Office
Prior art keywords
castings
cast iron
bainitic
obtaining
fact
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Withdrawn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
EP87116105A
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German (de)
English (en)
Inventor
Giuseppe Sola
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.)
Necchi SpA
Original Assignee
Necchi SpA
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 Necchi SpA filed Critical Necchi SpA
Publication of EP0271688A1 publication Critical patent/EP0271688A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/80—After-treatment
    • 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
    • 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
    • C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
    • C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
    • C21D7/06—Modifying the physical properties of iron or steel by deformation by cold working of the surface by shot-peening or the like

Definitions

  • the present invention refers to a process for obtaining bainitic nodular cast iron castings.
  • the bainitic structure is obtained as a rule from a standard cast iron with analytic field decidedly wider especially with reference to the manganese, the molybdenum, the copper and the nickel.
  • the technical problem to be solved was: - the obtaining of superior resistances and hardnesses in presence of toughness values proportionally superior to the values obtained with the traditional systems; - the obtaining of structures with "pitting" superficial resistances comparable to those of the best cement steels which have always had a better behaviour with respect to the bainitic austempered cast irons tested till now; - the obtaining of fracture and torsion resistances superior to those obtained with the normal already known methods.
  • the solution of the technical problem is characterized by the fact that the process comprises the following sequences: - heating of the castings till 500-600 °C and execution of a superficial nitriding treatment; - further heating till 870-950 °C for the austenitizing treatment of the matrix; - quick cooling of the castings in a water bath at a temperature between 70 and 300 °C; - bainitic transformation in a bath of salts between 225 and 350 °C; - shot peening of the castings at °Almen controlled; said process being applied when the analitic values of the alloy elements correspond to Mn ⁇ 0,20%, Ni ⁇ 1,0%, Cu ⁇ 1,0% and Mo ⁇ 0,5%.
  • the particularities of this process consist in a strict definition of the analytic field of the alloy elements with Mn ⁇ 0,20%, Ni ⁇ 1,0%, Cu ⁇ 1,0%, Mo ⁇ 0,5% and in the application of a particular austenitizing-temper-isothermic transformation cycle combined with a superficial nitriding of the piece.
  • the nodular cast iron castings are abtained with a perlitic-­ ferric matrix by whatever production technique usually employed. After mechanical working, the castings are subjected to austenitizing treatment of the matrix which occurs by heating the castings at a temperature comprised between 870 and 950 °C for a period comprised between 1 and 3 hours. When the temperature of 500-600 °C is reached, the heating is interrupted for a period variable from 0 to 24 hours in order to effect a treatment of superficial nitriding.
  • a cooling is effected as fast as possible by immersing the castings in a water bath at a temperture comprised between 70 and 300 °C for a period proportional to the temperature itself and comprised between 1 and 5 minutes, effecting in this way a quick temper.
  • C the zone of the diagram where the temper in water occurs at a very low temperature.
  • the bainitic transformation of the austenite is effected in salts bath at a temperature between 225 and 350 °C for a period comprised between 0,5 and 8 hours.
  • D the zone in which this transformation occurs.
  • the castings are subjected to shot peening and °Almen controlled.
  • the process object of the present invention is based on the severe narrowness of the alloy analytic values, in particular with reference to manganese, nickel, copper and molybdenum, and on a particular thermic cycle based in turn on austenitizing at high temperature and on isothermic transformation at low temperature with intermediate temper in water at a temperature lower than the transformation temperature.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Heat Treatment Of Articles (AREA)
EP87116105A 1986-11-20 1987-11-02 Procédé pour la fabrication de pièces moulées en fonte bainitique modulaire Withdrawn EP0271688A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT4291586 1986-11-20
IT8642915A IT1216347B (it) 1986-11-20 1986-11-20 Procedimento per ottenere getti in ghisa sferoidale bainitica

Publications (1)

Publication Number Publication Date
EP0271688A1 true EP0271688A1 (fr) 1988-06-22

Family

ID=11254704

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87116105A Withdrawn EP0271688A1 (fr) 1986-11-20 1987-11-02 Procédé pour la fabrication de pièces moulées en fonte bainitique modulaire

Country Status (2)

Country Link
EP (1) EP0271688A1 (fr)
IT (1) IT1216347B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0947589A1 (fr) * 1998-03-31 1999-10-06 Volkswagen Aktiengesellschaft Procédé de traitement d' une pièce métallique
TWI447230B (zh) * 2011-12-27 2014-08-01 Metal Ind Res & Dev Ct 沃斯回火球墨鑄鐵之製造方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2141175A1 (de) * 1971-08-17 1973-02-22 Kolomenskij Teplowosostroitel Verfahren zur verfestigung von teilen aus gusseisen mit kugelgraphit
US4222793A (en) * 1979-03-06 1980-09-16 General Motors Corporation High stress nodular iron gears and method of making same
WO1983001959A1 (fr) * 1981-12-03 1983-06-09 Hauke, Wilhelm Procede pour le durcissement bainitique au moins partiel de façon isothermique d'une piece en fonte
DE3407010A1 (de) * 1984-02-27 1985-09-05 J. Wizemann Gmbh U. Co, 7000 Stuttgart Koerper aus gehaertetem, metastabilem gusseisen und verfahren zur herstellung desselben

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2141175A1 (de) * 1971-08-17 1973-02-22 Kolomenskij Teplowosostroitel Verfahren zur verfestigung von teilen aus gusseisen mit kugelgraphit
US4222793A (en) * 1979-03-06 1980-09-16 General Motors Corporation High stress nodular iron gears and method of making same
WO1983001959A1 (fr) * 1981-12-03 1983-06-09 Hauke, Wilhelm Procede pour le durcissement bainitique au moins partiel de façon isothermique d'une piece en fonte
DE3407010A1 (de) * 1984-02-27 1985-09-05 J. Wizemann Gmbh U. Co, 7000 Stuttgart Koerper aus gehaertetem, metastabilem gusseisen und verfahren zur herstellung desselben

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JOURNAL OF HEAT TREATING, vol. 3, no. 4, December 1984, pages 326-334, American Society for Metals, Metals Park, Ohio, US; V.K. SHARMA: "Roller contact fatigue study of austempered ductile iron" *
PATENT ABSTRACTS OF JAPAN, vol. 6, no. 186 (C-126)[1064], 22nd September 1982; & JP-A-57 98 675 (TOYO KOGYO K.K.) 18-06-1982 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0947589A1 (fr) * 1998-03-31 1999-10-06 Volkswagen Aktiengesellschaft Procédé de traitement d' une pièce métallique
TWI447230B (zh) * 2011-12-27 2014-08-01 Metal Ind Res & Dev Ct 沃斯回火球墨鑄鐵之製造方法

Also Published As

Publication number Publication date
IT1216347B (it) 1990-02-22
IT8642915A0 (it) 1986-11-20

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