Evolution of microstructure, hardness and contact life of austenitic-martensitic TRIP steel VNS9-Sh under contact fatigue loading

The microstructure, microhardness of the near-surface layer, and contact fatigue of austenitic-martensitic TRIP steel VNS9-Sh (ВНС9-Ш) after tribotechnical test under loads corresponding to maximum normal stresses σZmax = 2500—4000 MPa have been investigated. It was established that an increase in stresses in the contact zone from 2500 to 4000 MPa contributed to an increase in the thickness of the near-surface layer with a hardness more than 290 HV, which had undergone martensitic transformation. The contact durability of VNS9-Sh steel with a decrease in contact stresses from 4000 to 2500 MPa increases by more than 63 times, and the limit of contact endurance of VNS9-Sh steel in the hardened state with a hardness of 220 HV is 2300 MPa, which is 15% higher than that of bearing steel 95X18 -SH with hardness 650 HV.