SEDL / STP / STP1327-EB / STP12137S

Study on the Limited Hardenability Steel

Xu, LP
Professor and professor, Shanghai University, Shanghai,

Li, L
Professor and professor, Shanghai University, Shanghai,

Min, YA
Assistant, Shanghai University, Shanghai,

Xu, MH
Chief engineer, Shanghai No.5 Steel CO. LTD., Shanghai,

Le, JP
General manager, Shanghai No.5 Steel CO. LTD., Shanghai,

Liu, RH
Engineer, Shanghai No.5 Steel CO. LTD., Shanghai,

Pages: 12    Published: Jan 1998

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Abstract

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) The matrix of the hardened layer was composed mainly of lath martensite with dispersed carbides whose formula was Me³ according to the X-ray spectrum analysis. The carbon content of martensite was estimated to be lower than 0.58% (by weight). The core was constituted of troostite transformed from spheroidal parbide. (3) The amount of retained austenite in the hardened layer was about 5% (in volume) which ensures the high dimensional stability of bearing.