Method for producing spheroidal graphite cast iron and vehicle component using said spheroidal graphite cast iron

Patent metadata

Field	Value
Publication number	US-9556498-B2
Application number	US-201214349727-A
Country	US
Kind code	B2
Filing date	Oct 5, 2012
Priority date	Oct 7, 2011
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

A method for producing spheroidal graphite cast iron having a specific final composition includes: subjecting a molten iron to a spheroidization treatment using a spheroidizing agent of an Fe—Si—Mg—Ca-based alloy containing no rare earth element; conducting an inoculation treatment using a first Fe—Si-based inoculant; and conducting a pouring inoculation treatment with a given amount of a second Fe—Si-based inoculant containing 45-75% of Si, 1-3% of Ca, and 15 ppm or less of Ba.

First claim

The invention claimed is:

1. A method for producing spheroidal graphite cast iron containing substantially no rare-earth element, the method comprising:
(a) a step of subjecting, in a ladle, a molten iron to a spheroidization treatment utilizing a spheroidizing agent of an Fe—Si—Mg-based alloy containing no rare-earth element or Fe—Si—Mg—Ca-based alloy containing no rare-earth element;
(b) a step of conducting an inoculation treatment utilizing a first Fe—Si-based inoculant, either simultaneously with the step (a) or after the step (a); and
(c) a step of adding a second Fe—Si-based inoculant to the molten iron in an amount of 0.20 to 0.40% in terms of % by mass after the step (b) to conduct a pouring inoculation treatment, the second Fe—Si-based inoculant containing, in terms of % by mass, 45 to 75% of Si, 1 to 3% of Ca, and 15 ppm or less of Ba,
wherein the spheroidal graphite cast iron to be obtained has a composition which contains, in terms of % by mass, 3.0 to 4.5% of C, 3.0 to 4.5% of Si, 0.2 to 0.4% of Mn, 0.006 to 0.020% of S, 0.08 to 0.30% of Cu, 0.020 to 0.040% of Sn, and 0.015 to 0.050% of Mg, with the remainder being Fe and unavoidable impurities.

2. The method for producing spheroidal graphite cast iron according to claim 1 , wherein the molten iron has a composition which contains, in terms of % by mass, 3.0 to 4.5% of C, 2.0 to 3.0% of Si, 0.2 to 0.4% of Mn, 0.006 to 0.020% of S, 0.08 to 0.30% of Cu, and 0.020 to 0.040% of Sn, with the remainder being Fe and unavoidable impurities.

3. A vehicle component comprising spheroidal graphite cast iron obtained by the production method according to claim 1 ,
the vehicle component having a degree of graphite spheroidization of 80% or higher, a tensile strength of 450 MPa or higher, and an elongation of 12% or higher,
wherein a chill area rate is 1% or less in a thin-wall part in which the vehicle component comprising the spheroidal graphite cast iron has a thickness of 6 mm or less.

4. A vehicle component comprising spheroidal graphite cast iron obtained by the production method according to claim 2 ,
the vehicle component having a degree of graphite spheroidization of 80% or higher, a tensile strength of 450 MPa or higher, and an elongation of 12% or higher, wherein a chill area rate is 1% or less in a thin-wall part in which the vehicle component comprising the spheroidal graphite cast iron has a thickness of 6 mm or less.

Assignees

• Akebono Brake Ind

Inventors

• Horiya Takao
• Baba Tsukasa
• TOKIYAMA Takuya
• Sato Takashi
• Idei Hiroshi

Classifications

• B22D1/00 Primary

  Treatment of fused masses in the ladle or the supply runners before casting {(for continuous casting B22D11/10; metallurgical processing, e.g. refining of iron or other metal C21, C22, C25C)} · CPC title

• C22C37/04

  containing spheroidal graphite · CPC title

• C22C28/00

  Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00 · CPC title

• C21C7/0006 Primary

  Adding metallic additives · CPC title

• C21D5/00

  Heat treatments of cast-iron · CPC title