Metal alloys for high impact applications

Patent metadata

Field	Value
Publication number	US-9273385-B2
Application number	US-201113576536-A
Country	US
Kind code	B2
Filing date	Feb 1, 2011
Priority date	Feb 1, 2010
Publication date	Mar 1, 2016
Grant date	Mar 1, 2016

Abstract

A casting of a white cast iron alloy and a method of producing the casting are disclosed. A white cast alloy is also disclosed. The casting has a solution treated microstructure that comprises a ferrous matrix of retained austenite and chromium carbides dispersed in the matrix, with the carbides comprising 15 to 60% volume fraction of the alloy. The matrix composition comprises: manganese: 8 to 20 wt %; carbon: 0.8 to 1.5 wt %; chromium: 5 to 15 wt %; and iron: balance (including incidental impurities).

First claim

The invention claimed is:

1. A casting of a white cast iron alloy having a solution treated microstructure, wherein the microstructure comprises:
(a) a ferrous matrix comprising retained austenite, the matrix having a composition of:
manganese: 8 to 20 wt %
carbon: 0.8 to 1.5 wt %;
chromium: 5 to 15 wt %; and
iron: balance (including incidental impurities); and

(b) chromium carbides dispersed in the matrix, the carbides comprising 5 to 60% volume fraction of the alloy.

2. The casting defined in claim 1 wherein the chromium concentration and/or the carbon concentration in a bulk chemistry of the white cast iron alloy is selected having regard to an inverse relationship between chromium concentration and carbon concentration in the matrix to control the matrix concentration of one or both of the chromium and the carbon to be within the ranges in the matrix defined in claim 1 so that the casting has required properties.

3. The casting defined in claim 1 wherein the matrix concentration of carbon is greater than 0.8 wt % and less than 1.5 wt %.

4. The casting defined in claim 1 wherein the matrix concentration of carbon is more than 1 wt %.

5. The casting defined in claim 1 wherein the carbides comprise 15 to 60% volume fraction of the casting.

6. The casting defined in claim 1 wherein the microstructure comprises 15 to 30 volume % carbides dispersed in the retained austenite matrix.

7. The casting defined in claim 1 wherein the carbides comprise chromium-iron-manganese carbides.

8. The casting defined in claim 1 wherein after solution treatment the ferrous matrix comprises primary austenite dendrites and/or eutectic austenite and the carbide phase comprise primary chromium-iron-manganese carbides and/or eutectic chromium-iron-manganese carbides.

9. The casting defined in claim 1 , further comprising niobium carbide and/or a chemical mixture of niobium carbide and titanium carbide.

10. The casting defined in claim 1 wherein the matrix is free of ferrite.

11. The casting defined in claim 1 comprising the following bulk composition:
chromium: 10 to 40 wt %;
carbon: 2 to 6 wt %;
manganese: 8 to 20 wt %;
silicon: 0 to 1.5 wt %; and
balance of iron and incidental impurities.

12. The casting defined in claim 1 comprising the following bulk composition:
chromium: 7 to 36 wt %;
carbon: 3 to 8.5 wt %;
manganese: 5 to 18 wt %;
silicon: 0 to 1.5 wt %;
titanium: 2 to 13 wt %; and
balance of iron and incidental impurities.

13. The casting defined in claim 1 comprising the following bulk composition:
chromium: 7 to 36 wt %;
carbon: 3 to 8.5 wt %;
manganese: 5 to 18 wt %;
silicon: 0 to 1.5 wt %;
niobium: 8 to 33 wt %; and
balance of iron and incidental impurities.

14. The casting defined in claim 1 comprising the following bulk composition:
chromium: 7 to 36 wt %;
carbon: 3 to 8.5 wt %;
manganese: 5 to 18 wt %;
silicon: 0 to 1.5 wt %;
niobium and titanium: 5 to 25 wt %; and
balance of iron and incidental impurities.

15. Equipment that is subject to severe abrasion and erosion wear that includes the casting defined in claim 1 .

16. A method of producing the casting defined in claim 1 comprising the steps of:
(a) forming a melt of a white cast iron alloy comprising the following bulk chemistry:
chromium: 7 to 36 wt %;
carbon: 3 to 8.5 wt %;
manganese: 5 to 18 wt %;
silicon: 0 to 1.5 wt %;
titanium: 2 to 13 wt %; and
balance of iron and incidental impurities;

(b) pouring the melt into a mould to form the casting; and
(c) allowing the casting to cool to room temperature.

17. The method defined in claim 16 further comprises heat treating the casting after step (c) by:
(d) heating the casting to a solution treatment temperature; and
(e) quenching the casting.

18. The casting defined in claim 2 wherein the required properties are selected from toughness, hardness, wear resistance, work hardening capacity, corrosion resistance, and any combination thereof.

19. The equipment defined in claim 15 , wherein the equipment is selected from slurry pumps and pipelines, mill liners, crushers, transfer chutes and ground-engaging tools.

Assignees

• Dolman Kevin
• Weir Minerals Australia Ltd

Inventors

• Dolman Kevin

Classifications

• C22C37/10

  containing aluminium or silicon · CPC title

• C22C33/08

  Making cast-iron alloys · CPC title

• C21D6/005

  containing Mn · CPC title

• C21D6/008

  containing Si · CPC title

• C21D6/002

  containing Cr (C21D6/004 takes precedence) · CPC title