Method and steel component

Patent metadata

Field	Value
Publication number	US-9828664-B2
Application number	US-201314422722-A
Country	US
Kind code	B2
Filing date	Aug 19, 2013
Priority date	Aug 21, 2012
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A method for heat treating a steel component, the method comprising steps of: (a) carbonitriding the steel component and (b) ferritically nitrocarburizing the steel component.

First claim

The invention claimed is:

1. A method for heat treating a steel component the method comprising steps of:
carbonitriding the steel component in a furnace in the presence of a first concentration of ammonia gas and at least one gas selected from the group consisting of methane, propane and natural gas,
decreasing the first concentration of ammonia gas to a second concentration of ammonia gas less than the first concentration during the carbonitriding; and
ferritically nitrocarburizing the steel component.

2. The method according to claim 1 , wherein the step of ferritically nitrocarburizing the steel component is carried out at a temperature below 590° C.

3. The method according to claim 1 , wherein the steel component comprises steel with a carbon content of 0.60 to 1.20 weight %.

4. The method according to claim 1 , wherein the steel component comprises one of a 100Cr6 steel or a 100CrMo7 steel.

5. The method according to claim 1 , wherein the steel component comprises or constitutes one of a rolling element, a roller, or a steel component for an application in which the steel component is subjected to alternating Hertzian stresses.

6. The method according to claim 1 , wherein, as a result of the method, the steel component is provided with a compound layer having a thickness of 10-20 μm.

7. The method according to claim 1 , wherein, as a result of the method, the steel component is provided with a surface hardness of 800-1000 HV and a core hardness of 300-500 HV.

8. The method according to claim 1 , wherein the step of ferritically nitrocarburizing the steel component is carried out in an atmosphere of 60% NH 3 , 35% N 2 and 5% CO 2 .

9. The method according to claim 1 , wherein the step of carbonitriding the steel component comprises carbonitriding the steel component for 5-25 hours.

10. The method according to claim 1 , the method further comprising a step of tumbling the steel component after the step of ferritically nitrocarburizing the steel component.

11. The method according to claim 1 , the method further comprising steps of c) quenching the steel component and d) tempering the steel component.

12. The method according to claim 10 , wherein the step of tempering the steel component is carried out at a temperature of 150-260° C.

13. The method according to claim 1 , wherein the method is provided for improving at least one of the following properties of a steel component: wear resistance, corrosion resistance, load bearing capacity, surface hardness, core hardness, compound layer thickness, abrasive wear resistance, and fatigue resistance.

14. The method according to claim 1 , wherein the first concentration is 9.5% and the second concentration is 6.5%.

15. The method according to claim 1 , wherein the first concentration is 9.5% and the second concentration is 0%.

16. The method according to claim 1 wherein the carbonitriding step has a duration and wherein the first concentration of ammonia gas is maintained for the first 70% of the duration.

17. The method according to claim 16 , wherein the first concentration is 9.5% and the second concentration is 6.5%.

18. The method according to claim 16 , wherein the first concentration is 9.5% and the second concentration is 0%.

Assignees

• Ab Skf (Publ)
• Skf Ab

Inventors

• Larsson Staffan
• Datchary Walter
• Flodström Isabella
• Neuman Peter

Classifications

• C21D9/36

  for balls; for rollers · CPC title

• C21D1/06

  Surface hardening · CPC title

• C23C8/32 Primary

  of ferrous surfaces · CPC title

• C21D9/40

  for rings; for bearing races · CPC title

• C21D9/38

  for roll bodies · CPC title