High-strength gray cast iron

Patent metadata

Field	Value
Publication number	US-2019177821-A1
Application number	US-201815978331-A
Country	US
Kind code	A1
Filing date	May 14, 2018
Priority date	Dec 8, 2017
Publication date	Jun 13, 2019
Grant date	—

Abstract

Disclosed herein is a gray cast iron having high strength and reduced casting defects. The high-strength gray cast iron may include: an amount of about 3.10 to 3.50 wt % of carbon (C), an amount of about 2.10 to 2.40 wt % of silicon (Si), an amount of about 0.50 to 0.80 wt % of manganese (Mn), an amount less than or equal to about 0.10 wt % (not including 0%) of phosphorus (P), an amount less than or equal to about 0.10 wt % (not including 0%) of sulfur (S), an amount of about 0.25 to 0.45 wt % of chromium (Cr), an amount of about 1.00 to 1.40 wt % of copper (Cu), an amount less than or equal to about 0.20 wt % (not including 0%) of nickel (Ni), and a balance of iron (Fe), all the wt % are based on the total weight of the gray cast iron. In particular, the gray cast iron may include a carbon equivalent (CEQ) of about 3.95 to 4.1% calculated by the Equation 1.

First claim

What is claimed is:

1 . A gray cast iron, comprising:
an amount of about 3.10 to 3.50 wt % of carbon (C), an amount of about 2.10 to 2.40 wt % of silicon (Si), an amount of about 0.50 to 0.80 wt % of manganese (Mn), an amount of less than or equal to about 0.10 wt % (not including 0%) of phosphorous (P), an amount of less than or equal to about 0.10 wt % (not including 0%) of sulfur (S), an amount of about 0.25 to 0.45 wt % of chromium (Cr), an amount of about 1.00 to 1.40 wt % of copper (Cu), an amount of less than or equal to about 0.20 wt % (not including 0%) of nickel (Ni), and a balance of iron (Fe), all the wt % are based on the total weight of the gray cast iron, wherein the gray cast iron has a carbon equivalent (CEQ) of about 3.95 to 4.1% calculated by the following equation 1:
Carbon equivalent (CEQ)=C+⅓(Si+P),  [Equation 1]

where each of C, Si, and Pin the Equation 1 represents an element content (wt %).

2 . The gray cast iron according to claim 1 , further comprising an amount of less than or equal to about 0.10 wt % of molybdenum (Mo).

3 . The gray cast iron according to claim 1 , wherein the gray cast iron has a solidification temperature of 1175 to 1185° C.

4 . The gray cast iron according to claim 1 , wherein the gray cast iron is formed with pearlite and ferrite and has a ferrite fraction of less than about 1%.

5 . The gray cast iron according to claim 1 , wherein the gray cast iron has a tensile strength of greater than or equal to about 300 MPa.

6 . The gray cast iron according to claim 1 , wherein the gray cast iron has a hardness of about 200 to 260 HB.

7 . The gray cast iron according to claim 1 , wherein the gray cast iron has a thermal conductivity of greater than or equal to about 45 W/mK.

8 . The gray cast iron according to claim 1 , wherein a chromium carbide is precipitated from the gray cast iron.

9 . The gray cast iron according to claim 8 , wherein the chromium carbide is precipitated at a ratio of about 1 to 2% from the gray cast iron.

10 . The gray cast iron according to claim 1 , consisting essentially of:
an amount of about 3.10 to 3.50 wt % of carbon (C); an amount of about 2.10 to 2.40 wt % of silicon (Si); an amount of about 0.50 to 0.80 wt % of manganese (Mn); an amount less than or equal to about 0.10 wt % (not including 0%) of phosphorus (P); an amount less than or equal to about 0.10 wt % (not including 0%) of sulfur (S); an amount of about 0.25 to 0.45 wt % of chromium (Cr); an amount of about 1.00 to 1.40 wt % of copper (Cu); an amount less than or equal to about 0.20 wt % (not including 0%) of nickel (Ni); and a balance of iron (Fe).

11 . The gray cast iron according to claim 1 , consisting of:
an amount of about 3.10 to 3.50 wt % of carbon (C); an amount of about 2.10 to 2.40 wt % of silicon (Si); an amount of about 0.50 to 0.80 wt % of manganese (Mn); an amount less than or equal to about 0.10 wt % (not including 0%) of phosphorus (P); an amount less than or equal to about 0.10 wt % (not including 0%) of sulfur (S); an amount of about 0.25 to 0.45 wt % of chromium (Cr); an amount of about 1.00 to 1.40 wt % of copper (Cu); an amount less than or equal to about 0.20 wt % (not including 0%) of nickel (Ni); and a balance of iron (Fe).

12 . A vehicle part comprising a gray cast iron of claim 1 .

13 . The vehicle part of claim 12 , wherein the vehicle part is an engine.

14 . A vehicle comprising a vehicle part of claim 12 .

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Park Hun Young

Classifications

• C22C37/08

  with nickel · CPC title

• C22C37/10 Primary

  containing aluminium or silicon · CPC title

• C22C37/06 Primary

  containing chromium · CPC title

• C21D2211/009

  Pearlite · CPC title

• C22C33/08

  Making cast-iron alloys · CPC title