Study on the limited hardenability steel

摘要

A series of measurements were taken in the limited hardenability bearing steel rings which were induction hardened and tempered. Measurements showed several features which strengthened the rings: (1) Compressive residual stress are generated from surface to a depth of 3.2mm and high residual compressive stress at the location where fatigue fracture initiates. (2) T he matrix of the hardened layer was composed mainly of lath marensite with dispersed carbides whose formula was Me_3 according tot he X-ray spectrum analysis. The carbon content of martensite was estimated to be lower than 0.58percent (by weight). The core was ccnstituted of troostite transformed from shperoidal carbide. (3) The amount of retained austenite in the hardened layer was about 5percent (in volume) which ensures the high dimensional stability of bearing.