US 12,276,032 B2
Method for treating a part made of ferrous metal, and part made of ferrous metal
Luc Hermann, Lyons (FR); and Vincent Monteux, La Talaudiere (FR)
Assigned to HYDROMECANIQUE ET FROTTEMENT, Andrezieux-Boutheon (FR)
Appl. No. 17/783,544
Filed by HYDROMECANIQUE ET FROTTEMENT, Andrezieux-Boutheon (FR)
PCT Filed Dec. 23, 2020, PCT No. PCT/FR2020/052620
§ 371(c)(1), (2) Date Jun. 8, 2022,
PCT Pub. No. WO2021/130460, PCT Pub. Date Jul. 1, 2021.
Claims priority of application No. 1915524 (FR), filed on Dec. 24, 2019.
Prior Publication US 2023/0029324 A1, Jan. 26, 2023
Int. Cl. C23C 8/80 (2006.01); C23C 8/26 (2006.01)
CPC C23C 8/80 (2013.01) [C23C 8/26 (2013.01)] 16 Claims
 
1. A method for treating a part made of ferrous metal, comprising:
a nitriding operation forming on the part a combination layer having a thickness of between 5 μm and 30 μm, and a diffusion region, arranged beneath and in contact with the combination layer, having a thickness of between 100 μm and 500 μm; then
an operation of quenching the part by high-frequency induction, over an induction depth that is greater than or equal to 0.5 mm, thereby hardening the part and lending said part:
a surface hardness greater than or equal to 50 HRC,
a hardness of the combination layer greater than or equal to 400 HV0.05,
a hardness of the part greater than or equal to 500 HV0.05 at a depth of 500 μm,
and wherein the high-frequency induction quenching operation is performed without the application of a protective film on the part prior to the induction quenching operation.