Method of heat treating a steel component

Patent metadata

Field	Value
Publication number	US-12534793-B2
Application number	US-202217827910-A
Country	US
Kind code	B2
Filing date	May 30, 2022
Priority date	Jun 2, 2021
Publication date	Jan 27, 2026
Grant date	Jan 27, 2026

Abstract

The present invention provides a method of heat treating a steel component including the sequential steps of: (a) carbonitriding the steel component; (b) quenching the steel component; (c) optionally tempering the steel component; and (d) ferritically nitrocarburizing the steel component.

First claim

The invention claimed is:

1 . A method of heat treating a steel component comprising the sequential steps of:
carbonitriding the steel component with a constant ammonia flow/percentage concentration of 15% at a temperature below 970° C.; after the step of carbonitriding and before ferritically nitrocarburizing, quenching the steel component in an oil bath; after the step of quenching, ferritically nitrocarburizing the steel component.

2 . The method of claim 1 , wherein the step of carbonitriding the steel component comprises carbonitriding the steel component for 5 to 30 hours.

3 . The method of claim 1 , further comprising: after the step of carbonitriding and after the step of quenching, tempering the steel component.

4 . The method of claim 1 , further comprising a step of tempering the steel component comprises tempering the steel component at a temperature of about 150 to about 620° C.

5 . The method of claim 1 , wherein ferritically nitrocarburizing the steel component comprises ferritically nitrocarburizing the steel component at a temperature of about 580° C. or less.

6 . The method of claim 1 , wherein the method further comprises either:
a step of furnace cooling the steel component after the step of ferritically nitrocarburizing; or a step of further quenching the steel component after the step of ferritically nitrocarburizing and then subsequently tempering the steel component.

7 . The method of claim 6 , wherein the method further comprises a step of machining the steel component before the step of ferritically nitrocarburizing and tumbling the steel component after any one of the steps of the group of: ferritically nitrocarburizing, or furnace cooling.

8 . The method of claim 1 , wherein the steel component has a carbon content of 0.10 to 1.20 wt. %, based on the total weight of the steel component.

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

10 . A heat-treated steel component treated by the method of heat treating a steel component having the sequential steps of:
heating the steel component from an initial room temperature of approximately twenty degrees Celsius to a carbonitriding temperature; carbonitriding the steel component while the steel component is at the carbonitriding temperature, wherein the carbonitriding of the steel component is accomplished with a constant ammonia flow/percentage concentration of fifteen percent (15%); after the step of carbonitriding and before the step ferritically nitrocarburizing, quenching the steel component for a predetermined duration sufficient to return the steel component to the initial room temperature; after the steps of carbonitriding and quenching, ferritically nitrocarburizing the steel component, wherein the heat-treated steel component comprises or constitutes a rolling element or roller, or an inner or outer ring of a bearing.

11 . The steel component of claim 10 , wherein the step of quenching the steel component comprises quenching the steel component in a salt or oil bath.

12 . The steel component of claim 10 , further comprising a step of tempering the steel component at a temperature of about 150 to about 620° C.

13 . The method of claim 2 , wherein ferritically nitrocarburizing the steel component comprises ferritically nitrocarburizing the steel component at a temperature of about 580° C. or less.

14 . The method of claim 1 , wherein the method further comprises machining the steel component before the step of ferritically nitrocarburizing and tumbling the steel component after any one of the steps of the group of: ferritically nitrocarburizing, or furnace cooling.

15 . The method of claim 1 , wherein the method further comprises tumbling the steel component after any one of the steps of the group of: ferritically nitrocarburizing, furnace cooling, or ferritically nitrocarburizing.

16 . The steel component of claim 10 , wherein the steel component has a carbon content of 0.10 to 1.20 wt. %, based on the total weight of the steel component.

17 . The method of claim 8 , wherein the steel component comprises a 100Cr6 steel or a 100CrMo7-3 steel.

Assignees

• Skf Ab

Inventors

• Larsson Karl Åke Staffan
• Ersson Marica

Classifications

• C21D1/607

  Molten salts · CPC title

• C21D1/58

  Oils · CPC title

• C23C8/80

  After-treatment · CPC title

• C21D9/40

  for rings; for bearing races · CPC title

• C21D9/36

  for balls; for rollers · CPC title