Duplex Hardening for Aerospace Bearing Steels

Abstract

A new process, duplex hardening, was developed, for two steels which are already widely used for aerospace applications, M50 and M50 NiL. The rolling contact fatigue and sliding wear performance of duplex hardened bearing components were evaluated on M50 and M50NiL steels. The rolling contact fatigue and sliding wear tests performed under the development program demonstrate superior performance of duplex hardened M50 and M50 NiL over conventional treated M50 and M50NiL bearing components. The bearing rig tests performed in this study also demonstrate superior bearing performance of duplex hardened M50 and M50NiL steels over conventional heat treated M50 resp. M50NiL steels. Under boundary lubricating conditions, the duplex hardened M50 and M50NiL bearings did not even fail after 1500 hrs. In tests with predamaged races, duplex hardened M50 bearing races demonstrated more than ten times the calculated L10-life. The tests on duplex hardened M50NiL bearings were interrupted after 1.500 hrs. runtime with no bearing failure.