Experiences in Heat Treatment of Heat Resistant Carburizing Bearing Steels

Abstract Rolling element bearings in aeroengine applications undergo high stresses and elevated temperatures. Besides through hardening grades, predominantly the high speed steel M50, often case hardening steels, mostly the high performance carburizing steel M50NiL, are used in critical aircraft engine applications. The advantage of case hardened steels compared to through hardened steels is a relatively high fracture toughness in the core. Furthermore, carburizing steels allow an integrated functional design. Sophisticated heat treatment cycles are necessary to get optimal microstructural properties. This paper presents properties of these steels and experiences in industrial processing, especially in carburizing and hardening.