Wear resistant cast iron

Patent metadata

Field	Value
Publication number	US-9222154-B2
Application number	US-55750904-A
Country	US
Kind code	B2
Filing date	May 21, 2004
Priority date	May 22, 2003
Publication date	Dec 29, 2015
Grant date	Dec 29, 2015

Abstract

A casting of a white cast iron alloy which includes the following alloy composition, in weight %:
chromium: 12-25%; carbon: 1.5-6%; manganese: 2-7%; silicon: up to 1.5%; molybdenum: up to 2; nickel: up to 4%; microalloying elements selected from the group of titanium, zirconium, niobium, boron, vanadium, and tungsten: up to 2% of each of one or more of the elements; and iron: balance.

The microstructure of the casting has 15-60 vol % eutectic carbides and primary carbides dispersed in a ferrous matrix of martensite and is at least substantially free of pearlite.

First claim

The invention claimed is:

1. A casting of a white cast iron alloy that comprises:
20 to 23 wt. % chromium;
3.3 to 6 wt. % carbon;
greater than 4 up to 7 wt. % manganese;
up to 1.5 wt. % silicon; and
the balance iron; and

having a microstructure comprising martensite, retained austenite and less than 2 vol. % pearlite and includes M 7 C 3 carbides, where “M” is a metal and “C” is carbon.

2. The casting of claim 1 , wherein the casting comprises greater than 4 up to 5.5 wt % manganese.

3. The casting of claim 1 , wherein the casting is free of nickel and molybdenum.

4. The casting of claim 1 , wherein the casting has a hardness of 700 HV 50.

5. The casting of claim 1 , wherein the casting is free of pearlite.

6. A hardened casting of a white cast iron alloy, hardened at 950° C. to 1000° C. for at least 4 hours, comprising:
20 to 23 wt. % chromium;
3.3 to 6 wt. % carbon;
greater than 4 up to 7 wt. % manganese;
up to 1.5 wt. % silicon; and
the balance iron; and
having a microstructure comprising martensite, retained austenite and less than 2 vol. % pearlite and includes M 7 C 3 carbides, where “M” is a metal and “C” is carbon.

7. The hardened casting of claim 6 , wherein the casting comprises greater than 4 up to 5.5 wt % manganese.

8. The hardened casting of claim 6 , wherein the casting is free of nickel and molybdenum.

9. The hardened casting of claim 6 , wherein the casting has a hardness of 700 HV 50.

10. The hardened casting of claim 6 , wherein the casting is free of pearlite.

11. The hardened casting of claim 6 , wherein the casting has a hardness of from 700-719 HV 50.

12. The hardened casting of claim 6 , wherein the microstructure of the hardened casting further comprises 32.4 to 60 vol. % eutectic carbides and primary carbides dispersed in a ferrous matrix that comprises martensite.

13. A method for producing a hardened white cast iron alloy casting, comprising:
a) pouring a molten melt of a white cast iron alloy to form a casting;
b) cooling the casting to room temperature; and
c) hardening the casting by heating the casting to a temperature of from 950° C. to 1000° C. and holding the casting at 950° C. to 1000° C. for at least 4 hours to destabilize austenite to form the hardened white cast iron alloy casting composed of:
20 to 23 wt. % chromium;
3.3 to 6 wt. % carbon;
greater than 4 up to 7 wt. % manganese;
up to 1.5 wt. % silicon; and
the balance iron; and

having a microstructure comprising martensite, retained austenite and less than 2 vol. % pearlite and includes M 7 C 3 carbides, where “M” is a metal and “C” is carbon.

14. The method of claim 13 , wherein the white cast iron alloy is free of nickel and molybdenum.

15. The method of claim 13 , wherein the white cast iron alloy comprises greater than 4 up to 5.5 wt % manganese.

16. The method of claim 13 , wherein the microstructure of the hardened white cast iron alloy casting further comprises 32.4 to 60 vol. % eutectic carbides and primary carbides dispersed in a ferrous matrix that comprises martensite.

17. The method of claim 13 , wherein the hardened white cast iron alloy casting has a hardness of 700 HV 50.

18. The method of claim 13 , wherein the casting is free of pearlite.

19. The method of claim 13 , wherein the casting has a hardness of from 700-719 HV 50.

Assignees

• Dolman Kevin Francis
• Weir Minerals Australia Ltd

Inventors

• Dolman Kevin Francis

Classifications

• C21D2211/004

  Dispersions; Precipitations · CPC title

• C21D5/04

  of white cast-iron · CPC title

• C22C37/10

  containing aluminium or silicon · CPC title

• C22C37/08

  with nickel · CPC title

• C22C37/06 Primary

  containing chromium · CPC title