The bearing rig tests performed in this study, demonstrate superior bearing performance of Cronidur 30 steel over conventional bearing steels. In these tests the L10 life of Cronidur 30 steel as calculated by the DIN/ISO 281 method was 80 times the unfactored L10 life under full lubrication conditions. In boundary lubrication conditions, the Cronidur 30 steel demonstrated the L10 life capability typical of EHD lubrication conditions, whereas the other steels showed a drastically reduced lives. In tests with predamaged races and boundary lubrication conditions, Cronidur 30 demonstrated 8 times the calculated L10 life, whereas the conventional steels exhibited further debit in lives as compared to the boundary lubrication testing whithout predamage. The improved performance of Cronidur 30 steel over conventional bearing steels is attributed to its unique compositional formulation and microstructure that results in provision of balanced properties in the alloy – hardness, toughness and corrosion resistance.
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.
Reliability is one of the most important competitive factors in aeroengines. Engine manufacturers have to provide guarantees for maintenance cost and dispatch reliability. Failures of mainshaft and gearbox bearings can represent a major debit to overall engine reliability. Duplex hardening (conventional hardening followed by special nitriding) has the potential to provide the bearing performance improvements necessary to yield increased engine reliability and reduced cost of ownership. The bearing rig tests performed demonstrate superior performance of duplex hardened M50 and M50NiL bearings over conventional M50 and M50NiL bearings under various operating conditions. Rig tests evaluating a wide range of operating conditions, such as high load, low or boundary lubrication, heavily contaminated lubrication, and oil off were performed. Additional tests were completed to evaluate the spall propagation behavior of duplex hardened bearings in comparison to conventional steel bearings. The results showed that the main benefits of using duplex hardened bearings arise in low or boundary lubrication conditions and contaminated lubrication conditions. The spall propagation tests showed that spall propagation rates are slower for duplex hardened M50 and M50NiL bearing components, hence allowing more time until catastrophic bearing failure in an aeroengine and other applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.