Process for case-hardening rolling bearing elements of low-alloy nickeliferous steel

In a process for case-hardening rolling bearing elements of low-alloy nickeliferous steel, comprising the steps of producing a carburized layer by holding said rolling bearing elements in a carburizing furnace at a carburizing temperature of about 970.degree. C. in the presence of a carburizing gas which dissociates into carbon and hydrogen;

• cooling said rolling bearing elements;
• heating said cooled rolling bearing elements to hardening temperature;
• austenitizing said rolling bearing elements in the carburization layer;
• and quenching said austenitized rolling bearing elements to obtain a surface hardness of 60 to 64 RHC,
• the improvement wherein the step of cooling comprises cooling said rolling bearing elements from the carburizing temperature down to a temperature of about 300.degree. C. in the presence of an agitated inert gas at a cooling rate which prevents precipitation of intercrystalline carbides in the steel structure and holding said rolling bearing elements at said temperature of about 300.degree. C. in the presence of said inert gas so as to diffuse additional hydrogen out of said carburization layer,
• whereby said cooling rate allows a substantial amount of the dissociated hydrogen of the carburizing gas to diffuse out of said carburized layer.