To provide a rolling member which has longer life, superior abrasion resistance and superior seizing resistance, by optimizing an Si-Mn-based nitride.
For instance, a rolling element 3 has an Si-Mn-based nitride formed on its surface layer through carbonitriding treatment or nitriding treatment. The surface layer is controlled so as to include 0.2 wt.% or more of nitrogen concentration, include 1% or more and less than 10% of an area rate of Si-Mn-based nitrides, and include the number of 100 pieces or more in 375 μm2 of the area of Si-Mn-based nitrides of 0.05 to 1 μm. Thereby, high strength is obtained by increasing the deposition amount of fine nitride to shorten a distance between the Si-Mn-based nitrides. Higher strength can be obtained by using a steel, which includes 0.3 to 2.2 wt.% Si and 0.3 to 2.0 wt.% Mn while controlling a ratio Si/Mn to 5 or less and which is subjected to carbonitriding quenching and tempering treatment.
UEDA TORU
SENO NAOYA
MITAMURA NOBUAKI
Megumi Konishi
Hide Tanaka Tetsu
Ichi Hirose
Toru Miyasaka