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
  • C21C1/08—Manufacture of cast-iron
• • 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

Definitions

• the invention relates to a process for producing a cast iron with predominantly vermicular graphite form (GGV), in which a treatment additive is added to a base iron melt.
• GGV vermicular graphite form
• CGI was initially iron as undesirable graphite precipitation in the production of G USS with K ugelgraphit in the case of inadequate treatment with ball-forming additives or even in thick-walled parts made of cast iron with spheroidal graphite viewed.
• cast iron with vermicular graphite consist in particular in the fact that cast iron with vermicular graphite shows a similarly good casting and blowout behavior as cast iron with lamellar graphite, but with regard to its material properties can be approximated to that of spheroidal graphite, so that it can be approximated
• Cast iron is ideally suited as an intermediate strength material for, for example, castings with complicated castings.
• cast iron with vermicular graphite has a very good thermal conductivity and can also due to a low modulus of elasticity for components subject to temperature changes, e.g. B. cylinder heads, exhaust manifolds of internal combustion engines, can be used successfully, so that this material will become increasingly important insofar as it is possible to master the difficult manufacture of this material, particularly with regard to stepped strength ranges.
• GB-PS 1,069,058 describes a production process in which a spheroidal cast-banisein melt is treated with a treatment additive composed of magnesium, titanium and rare earth metals, titanium being said to interfere with the formation of spheroidal graphite.
• a production process thus places the high demands on the purity of the base iron melt (trace elements, interfering elements) that are necessary in the production of spheroidal cast iron and only leads to process conditions that are exactly adhered to so that hereby arise the desired Vermiculargraphit TR, disposal costs erti- at a large-scale application considerable F.
• the addition of the interfering element titanium due to carbide formation in cast iron can also adversely affect the material properties and machinability and is particularly disadvantageous with regard to the recyclability of the cast iron piece as a raw material for later cast iron remelting.
• This object is surprisingly achieved in the generic method for producing cast iron with vermicular graphite in that pure magnesium is added to the base iron melt as a treatment additive.
• cast iron with vermicular graphite can be produced particularly accurately and reproducibly and in particular graded according to strength values without the addition of further treatment additives.
• the treated base iron melt is advantageously free from any interfering elements such as titanium, and, in contrast to the known base iron melts, has a very long decay time, so that the risk of vermicular graphite formation tipping over into a lamellar structure is greatly reduced, which apparently does not affect the existing ones and in known processes, alloy additives with a vaccine effect can be attributed.
• Each according to the desired material quality it is possible according to the invention to subject the base iron melt to a pre-desulfurization before the pure magnesium is added, and it has surprisingly been found that pre-desulfurization by means of pure magnesium is particularly advantageous. But it is also possible to use a sulfur-rich B asisei- senschmelze by other known means such. B. CaC 2 , lime, soda or the like. Before the addition of the pure magnesium treatment additive.
• 0.05 to 0.3% by weight of pure magnesium is preferably added to the base iron melt as a treatment additive.
• the pure magnesium can be introduced particularly advantageously by means of an immersion bulb. Such a diving bulb is known from DE-PS 22 08 960 and described in detail there.
• Example 1 a base iron melted in an electric furnace with 3.70% C, 1.71% Si, 0.25% Mn and 0.025% S was treated with pure magnesium in various ways.
• the table below gives an overview of the different strength values determined in this cast iron with vermicular graphite according to the invention in the finished castings as a function of the residual magnesium content.
• This presulfurized base iron melt was subsequently heated in an electric furnace to a treatment addition temperature and then with 1.8 kg of pure magnesium, which was introduced into the base iron melt by means of an immersion bulb, treated for the following casting analysis:
• flywheels each with a gross weight of 600 kg and a diameter of 1000 mm and a wall thickness of 140 - 150 mm, were cast from this cast iron melt. The following strength values were achieved:

Landscapes

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

Applications Claiming Priority (2)

Publications (2)

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ID=6201369

Family Applications (1)

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Cited By (1)

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• 1983
  • 1983-06-13 DE DE19833321312 patent/DE3321312A1/de not_active Withdrawn
• 1984
  • 1984-04-02 EP EP84103633A patent/EP0131092A3/fr not_active Withdrawn
  • 1984-06-08 JP JP11682684A patent/JPS609812A/ja active Pending

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