Spheroidal graphite cast iron, cast article and automobile structure part made thereof, and method for producing spheroidal graphite cast iron article

Patent metadata

Field	Value
Publication number	US-12522901-B2
Application number	US-202318235572-A
Country	US
Kind code	B2
Filing date	Aug 18, 2023
Priority date	Mar 24, 2016
Publication date	Jan 13, 2026
Grant date	Jan 13, 2026

Abstract

A spheroidal graphite cast iron meeting N(5-)≥250, N(5-20)/N(5-)≥0.6, and N(30-)/N(5-)≤0.2, wherein N(5-) represents the number (/mm2) of graphite particles having equivalent-circle diameters of 5 μm or more, N(5-20) represents the number (/mm2) of graphite particles having equivalent-circle diameters of 5 μm or more and less than 20 μm, and N(30-) represents the number (/mm2) of graphite particles having equivalent-circle diameters of 30 μm or more, among graphite particles observed in an arbitrary cross section of at least 1 mm2.

First claim

What is claimed is:

1 . A method for producing a cast article of spheroidal graphite cast iron meeting the following conditions:
N (5-) ≥250,
N (5-20) /N (5-) ≥0.6, and
N (30-) /N (5-) ≤0.2,

wherein N (5-) , N (5-20) , and N (30-) are the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 5 μm or more, the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 5 μm or more and less than 20 μm, and the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 30 μm or more, respectively, among graphite particles observed in an arbitrary cross section of at least 1 mm 2 ; comprising
pouring a melt into a gas-permeable casting mold by gravity-casting,
pressing a surface of the melt in the gas-permeable casting mold by a gas at a pressure of 1-100 kPa, before said melt starts eutectic solidification; and
solidifying said melt while supplying said gas into said casting mold,

wherein said method meets
0< dt pE /dt E ≤1/2,

wherein dt E represents a time period from the start of eutectic solidification of said melt to the completion of the eutectic solidification, and dt pE represents a time period from the start of eutectic solidification of said melt to the completion of said pressing.

2 . The method for producing a cast article according to claim 1 , wherein said pressure is 10-50 kPa.

3 . The method for producing a cast article according to claim 1 , wherein said gas-permeable casting mold is a green sand mold, a shell mold, or a self-hardening mold, constituted by sand particles.

4 . The method for producing a cast article according to claim 1 , wherein the spheroidal graphite cast iron has a composition comprising by mass 2-4.5% of C, 0.8-2.26% of Si, and 0.010-0.080% of Mg, the balance being Fe and inevitable impurity elements and optionally one or more of S, P, Mn, Cu, Cr, Ni, Mo, W,
wherein said graphite particles meet N (2-5) ≥100, wherein N (2-5) represents the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 2 μm or more and less than 5 μm, wherein said graphite particles meet D max ≥50.4 μm, wherein D max represents the maximum equivalent-circle diameter of graphite particles, and wherein said graphite particles meet −0.15≤[N (5-10) -N (15-20) ]/N (5-10) ≤0.25, wherein N (5-10) represents the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 5 μm or more and less than 10 μm, and N (15-20) represents the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 15 μm or more and less than 20 μm.

5 . The method for producing a cast article according to claim 1 , wherein said method meets 0<dt pE /dt E ≤1/4.

6 . The method for producing a cast article according to claim 1 , wherein said method meets 1/4≤dt pE /dt E ≤1/2.

7 . The method for producing a cast article according to claim 1 , wherein said method meets 1/4≤dt pE /dt E <1/2.

8 . The method for producing a cast article according to claim 1 , wherein the gas is supplied to monotonically increase the pressing pressure from the start.

9 . A method for producing a cast article of spheroidal graphite cast iron meeting the following conditions:
N (5-) ≥250,
N (5-20) /N (5-) ≥0.6, and
N (30-) /N (5-) ≤0.2,

wherein N (5-) , N (5-20) , and N (30-) are the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 5 μm or more, the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 5 μm or more and less than 20 μm, and the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 30 μm or more, respectively, among graphite particles observed in an arbitrary cross section of at least 1 mm 2 ; comprising
pouring a melt into a gas-permeable casting mold by gravity-casting,
pressing a surface of the melt in the gas-permeable casting mold by a gas at a pressure of 1-100 kPa, before said melt starts eutectic solidification; and
solidifying said melt while supplying said gas into said casting mold,

wherein said method meets
0< dt pE /dt E ≤1/1.9,

wherein dt E represents a time period from the start of eutectic solidification of said melt to the completion of the eutectic solidification, and dt pE represents a time period from the start of eutectic solidification of said melt to the completion of said pressing.

10 . The method for producing a cast article according to claim 9 , wherein said pressure is 10-50 kPa.

11 . The method for producing a cast article according to claim 9 , wherein said gas-permeable casting mold is a green sand mold, a shell mold, or a self-hardening mold, constituted by sand particles.

12 . The method for producing a cast article according to claim 9 , wherein the spheroidal graphite cast iron has a composition comprising by mass 2-4.5% of C, 0.8-2.26% of Si, and 0.010-0.080% of Mg, the balance being Fe and inevitable impurity elements and optionally one or more of S, P, Mn, Cu, Cr, Ni, Mo, W,
wherein said graphite particles meet N (2-5) ≥100, wherein N (2-5) represents the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 2 μm or more and less than 5 μm, wherein said graphite particles meet D max ≥50.4 μm, wherein D max represents the maximum equivalent-circle diameter of graphite particles, and wherein said graphite particles meet −0.15≤[N (5-10) -N (15-20) ]/N (5-10) ≤0.25, wherein N (5-10) represents the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 5 μm or more and less than 10 μm, and N (15-20) represents the number (/mm 2 ) of graphite particles having equivalent-circle diameters of 15 μm or more and less than 20 μm.

13 . The method for producing a cast article according to claim 9 , wherein the gas is supplied to monotonically increase the pressing pressure from the start.

Assignees

• Proterial Ltd

Inventors

• Wang Lin

Classifications

• C22C37/10

  containing aluminium or silicon · CPC title

• C22C33/10

  including procedures for adding magnesium · CPC title

• C21C1/10

  Making spheroidal graphite cast-iron · CPC title

• C22C37/04 Primary

  containing spheroidal graphite · CPC title