Abstract: A bearing component is prepared from a carburazing steel and having a surface hardness of 63 to 67 in terms of Rockwell hardness C and a surface retained austenite content of at least 20% to less than 25%. The bearing component is produced by a process including the step of carburizing and quenching a bearing component workpiece prepared from a carburizing steel and machined to a predetermined shape, the step of subjecting the resulting workpiece to a preliminary tempering treatment, the step of subjecting the tempered workpiece to a sub-zero treatment and the step of subjecting the treated workpiece to a main tempering treatment. Further, the bearing component is produced by another process including the step of carburizing and quenching a bearing component workpiece prepared from a carburizing steel and machined to a predetermined shape, the step of subjecting the resulting workpiece to a secondary hardening treatment and the step of subjecting the hardened workpiece to a main tempering treatment.

Abstract: A method of cooling steel parts from austenitic stage to a temperature that is higher than its Ms point after carburization of said steel part to carry out diffusion transformation, then carrying out a nitriding treatment and further applying shot peening, and in order to implement said method provide a carburizing zone, a cooling zone for carrying out diffusion transformation and a nitriding treatment zone connected through opening and shutting doors, and provide feeding devices in each of said zones to feed the steel parts to the next zone.

Abstract: In subjecting a steel workpiece to nitriding by glow discharge, formation of brittle nitrogen compound is restrained and the surface hardened layer with a nitrogen diffusion layer of high toughness is obtained by making the gas atmospheric condition the gas mixing ratio of N.sub.2 :H.sub.2 =1:2-40. By mixing Ar gas in the above gas atmospheric condition additionally, glow width is adjusted and glow discharge is allowed to enter into narrow concaves at the surface of a workpiece.

Abstract: A hard wear-resistant and corrosion- and oxidation-resistant stainless steel article is made by precision machining a work piece of approximately the size and shape of the desired article, then subjecting the resulting cold worked article to ion bombardment until the article is nitrided to a depth of about 0.002 inch, and finally subjecting the nitrided article to an atmosphere of argon and nitrogen and oxygen until the resulting ion bombardment has penetrated to a depth in the article surface of about 0.0001 inch.