Method for producing powder metal compositions for wear and temperature resistance applications

Patent metadata

Field	Value
Publication number	US-10543535-B2
Application number	US-201715703552-A
Country	US
Kind code	B2
Filing date	Sep 13, 2017
Priority date	Apr 8, 2008
Publication date	Jan 28, 2020
Grant date	Jan 28, 2020

Abstract

A powder metal composition for high wear and temperature applications is made by atomizing a melted iron based alloy including 3.0 to 7.0 wt. % carbon; 10.0 to 25.0 wt. % chromium; 1.0 to 5.0 wt. % tungsten; 3.5 to 7.0 wt. % vanadium; 1.0 to 5.0 wt. % molybdenum; not greater than 0.5 wt. % oxygen; and at least 40.0 wt. % iron. The high carbon content reduces the solubility of oxygen in the melt and thus lowers the oxygen content to a level below which would cause the carbide-forming elements to oxidize during atomization. The powder metal composition includes metal carbides in an amount of at least 15 vol. %. The microhardness of the powder metal composition increases with increasing amounts of carbon and is typically about 800 to 1,500 Hv50.

First claim

What is claimed is:

1. A method of forming a powder metal composition, comprising the steps of:
providing a melted iron based alloy including 3.0 to 7.0 wt. % carbon, 10.0 to 25.0 wt. % chromium, 1.0 to 5.0 wt. % tungsten, 3.5 to 7.0 wt. % vanadium, 1.0 to 5.0 wt. % molybdenum, not greater than 0.5 wt. % oxygen, and at least 40.0 wt. % iron, based on the total weight of the melted iron based alloy; and
atomizing the melted iron based alloy to provide atomized droplets of the iron based alloy, the atomizing step including forming metal carbides in an amount of at least 15 vol. %, based on the total volume of the melted iron based alloy.

2. The method of claim 1 including grinding the atomized droplets to remove an oxide skin from the atomized droplets.

3. The method of claim 1 , wherein the metal carbides are selected from the group consisting of: M 8 C 7 , M 7 C 3 , M 6 C, wherein M is at least one metal atom and C is carbon.

4. The method of claim 3 , wherein M 8 C 7 is (V 63 Fe 37 ) 8 C 7 ; M 7 C 3 is selected from the group consisting of: (Cr 34 Fe 66 ) 7 C 3 , Cr 3.5 Fe 3.5 C 3 ; and M 6 C is selected from the group consisting of: Mo 3 Fe 3 C, Mo 2 Fe 4 C, W 3 Fe 3 C, and W 2 Fe 4 C.

5. The method of claim 1 , wherein the metal carbides include vanadium-rich carbides in an amount of about 5.0 to 10.0 vol. % and chromium-rich carbides in an amount of about 40.0 to 45.0 vol. %, based on the total volume of the melted iron based alloy.

6. The method of claim 1 , wherein the melted iron based alloy includes 3.5 to 4.0 wt. % carbon, 11.0 to 15.0 wt. % chromium, 1.5 to 3.5 wt. % tungsten, 4.0 to 6.5 wt. % vanadium, 1.0 to 3.0 wt. % molybdenum, not greater than 0.3 wt. % oxygen, and 50.0 to 81.5 wt % iron, based on the total weight of the melted iron based alloy.

7. A method of forming a powder metal composition, comprising the steps of:
providing a melted iron based alloy consisting of 3.8 wt. % carbon, 13.0 wt. % chromium, 2.5 wt. % tungsten, 6.0 wt. % vanadium, 1.5 wt. % molybdenum, 0.2 wt. % oxygen, 70.0 to 80.0 wt. % iron, and impurities in an amount not greater than 2.0 wt. %, based on the total weight of the melted iron based alloy; and
atomizing the melted iron based alloy to provide atomized droplets of the iron based alloy.

8. A method of forming a sintered article, comprising the steps of:
providing a melted iron based alloy including 3.0 to 7.0 wt. % carbon, 10.0 to 25.0 wt. % chromium, 1.0 to 5.0 wt. % tungsten, 3.5 to 7.0 wt. % vanadium, 1.0 to 5.0 wt. % molybdenum, not greater than 0.5 wt. % oxygen, and at least 40.0 wt. % iron, based on the total weight of the melted iron based alloy;
atomizing the melted iron based alloy to provide atomized droplets of the iron based alloy, the atomizing step including forming metal carbides in an amount of at least 15 vol. %, based on the total volume of the melted iron based alloy;
optionally grinding the atomized droplets;
compacting the droplets to form a preform; and
sintering the preform.

9. The method of claim 8 including annealing the droplets prior to the sintering step.

10. The method of claim 8 , wherein the metal carbides are selected from the group consisting of: M 8 C 7 , M 7 C 3 , M 6 C, wherein M is at least one metal atom and C is carbon.

11. The method of claim 10 , wherein M 8 C 7 is (V 63 Fe 37 ) 8 C 7 ; M 7 C 3 is selected from the group consisting of: (Cr 34 Fe 66 ) 7 C 3 , Cr 3.5 Fe 3.5 C 3 ; and M 6 C is selected from the group consisting of: Mo 3 Fe 3 C, Mo 2 Fe 4 C, W 3 Fe 3 C, and W 2 Fe 4 C.

12. The method of claim 8 , wherein the metal carbides include vanadium-rich carbides in an amount of about 5.0 to 10.0 vol. % and chromium-rich carbides in an amount of about 40.0 to 45.0 vol. %, based on the total volume of the melted iron based alloy.

13. The method of claim 8 including admixing at least 30.0 wt. % of an alloyed steel powder different from the iron based alloy with the atomized droplets.

14. The method of claim 8 , wherein the iron based alloy includes 3.5 to 4.0 wt. % carbon, 11.0 to 15.0 wt. % chromium, 1.5 to 3.5 wt. % tungsten, 4.0 to 6.5 wt. % vanadium, 1.0 to 3.0 wt. % molybdenum, not greater than 0.3 wt. % oxygen, and 50.0 to 81.5 wt % iron, based on the total weight of the melted iron based alloy.

15. A method of forming a sintered article, comprising the steps of:
providing a melted iron based alloy consisting of 3.8 wt. % carbon, 13.0 wt. % chromium, 2.5 wt. % tungsten, 6.0 wt. % vanadium, 1.5 wt. % molybdenum, 0.2 wt. % oxygen, 70.0 to 80.0 wt. % iron, and impurities in an amount not greater than 2.0 wt. %, based on the total weight of the melted iron based alloy;
atomizing the melted iron based alloy to provide atomized droplets of the iron based alloy;
optionally grinding the atomized droplets;
compacting the droplets to form a preform; and

sintering the preform.

Assignees

• Fed Mogul Llc
• Corp De Lecole Polytechnique De Montreal
• Tenneco Inc

Inventors

• Beaulieu Philippe
• Christopherson Jr Denis B
• Farthing Leslie John
• Schoenwetter Todd
• L'Espérance Gilles

Classifications

• B22F1/00

  Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties · CPC title

• B22F2009/0828

  with water · CPC title

• B22F3/1017

  Multiple heating or additional steps (B22F3/101 takes precedence) · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title

• C22C1/02

  by melting {(C22C1/1036 takes precedence)} · CPC title