Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C1/00—Refining of pig-iron; Cast iron
  • C21C1/10—Making spheroidal graphite cast-iron
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C35/00—Master alloys for iron or steel
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C1/00—Refining of pig-iron; Cast iron
  • C21C1/10—Making spheroidal graphite cast-iron
  • C21C1/105—Nodularising additive agents

Definitions

• the present invention relates to a process for obtaining cast iron with spheroidal graphite by late treatment of the cast iron by means of a single nodulating additive making it possible to avoid inoculation.
• Spheroidal graphite molding irons are normally obtained by treating a basic cast iron with a first additive known as "nodulating" which ensures the formation of nodular or spheroidal graphite, and which is most often magnesium, for example in the form of 'an iron-silicon-magnesium alloy, with or without rare earth, then with an inoculant which modifies the germination of graphite and prevents the formation of cementite which would weaken the cast iron; the inoculant is most often based on silicon, for example an iron-silicon alloy.
• nodulating which ensures the formation of nodular or spheroidal graphite, and which is most often magnesium, for example in the form of 'an iron-silicon-magnesium alloy, with or without rare earth
• the solution then consists in constituting a reserve of untreated molten cast iron and in carrying out a "late” treatment, by nodulization then inoculation, in the few moments preceding the introduction of the cast iron into the imprint of the pieces at inside the molds.
• the present invention can be implemented in both "in-mold” and “jet” processes and, in general, in all late treatment processes, that is to say in the few moments preceding the introduction of cast iron into the cavities of the pieces inside the molds.
• the object of the present invention is a process for producing spheroidal or vermicular cast iron, characterized in that a late treatment of the basic cast iron is carried out by means of a single additive, simultaneously ensuring nodulization and l inoculation, this additive being a ferro-silico-magnesium comprising an addition of bismuth and at least one metal from the Rare Earth family.
• the present invention makes it possible to avoid the inoculation stage and to directly obtain a spheroidal cast iron having a high number of graphite nodules, and a total absence of carbides even in the case of very thin pieces: a few millimeters.
• the additive used to obtain this result has a composition within the following limits (expressed in percent by weight): Silicon: 41 to 65 Magnesium: 2 to 30 Bismuth: 0.1 to 4 Rare earth : 0.5 to 4 Ca, Ba, Sr: ⁇ to 4 (for each element) Al: ⁇ 1.5 Iron : difference to 100
• rare earths will denote at least one metal from the group of lanthanides, in particular cerium, possibly associated with other metals of the same family (such as lanthanum) in a variable proportion according to the origin of the ore and the treatments it has undergone.
• the process which is the subject of the invention is essentially distinguished by the fact that it combines nodulization and inoculation in a single operation which is carried out "late”, which leads to a simplification of the procedures and equipment used, thus a gain in cost price and productivity of the foundry workshop.
• the invention has been implemented with the device which is the subject of our application FR 2588571, often called "hourglass" because of its particular shape and which allows the direct introduction of the finely sprayed additive into the casting jet. in a controlled atmosphere.
• a spheroidal cast iron was prepared having the following final composition (% by weight): C: 3.7 Si: 2.5 Mn: 0.15 P: 0.043 Mg: 0.039
• the nodulant was introduced at a dose of 1% of the weight of the cast iron.
• the cast iron was poured, at a temperature of 1400 ° C, in the form of bars having diameters of 30, 20, 12 and 6 millimeters.
• the moldings were made in Beta Set sand.
• the quantity of additive to be introduced into the basic cast iron is determined by those skilled in the art as a function of the final content targeted, in the cast iron, of the two magnesium elements and bismuth. Average contents of 0.025 to 0.060% by weight of magnesium and 0.005 to 0.02 of bismuth are generally considered to be satisfactory. They can therefore be obtained, taking into account the volatility of the two elements, with an amount of additive of the order of 1% relative to the weight of cast iron to be treated.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Mold Materials And Core Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=9369501

Family Applications (1)

Country Status (8)

Cited By (13)

Families Citing this family (7)

Citations (3)

Family Cites Families (1)

• 1988
  • 1988-08-12 FR FR8811190A patent/FR2635534B1/fr not_active Expired - Lifetime
• 1989
  • 1989-08-08 CA CA000607776A patent/CA1337148C/fr not_active Expired - Fee Related
  • 1989-08-08 JP JP1205566A patent/JPH0280505A/ja active Pending
  • 1989-08-10 ES ES89420304T patent/ES2055140T3/es not_active Expired - Lifetime
  • 1989-08-10 DE DE8989420304T patent/DE68906489T2/de not_active Expired - Fee Related
  • 1989-08-10 EP EP89420304A patent/EP0357521B1/de not_active Expired - Lifetime
  • 1989-08-10 BR BR898904037A patent/BR8904037A/pt not_active Application Discontinuation
  • 1989-08-11 KR KR1019890011457A patent/KR930011403B1/ko not_active Expired - Fee Related

Patent Citations (3)

Non-Patent Citations (2)

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