Improve fatigue and mechanical properties of high carbon bearing steel by a new double vacuum melting route
Zhiyue Shi, Hui Wang, Yuanhang Gao, Yutong Wang, Feng Yu, Haifeng Xu, Xiaodan Zhang, Chengjia Shang, Wenquan Cao
Abstract
Abstract A new double vacuum melting route (conventional second refining + vacuum arc refining [CSR + VAR]) with 33% lower production cost than the traditional VIM + VAR route has been tried. Compared with the CSR route, the CSR + VAR route reduces the average inclusion size from 27.1 ± 12.3 μm to 13.7 ± 2.4 μm, and the CSR + VAR steel processes a 13.1% higher rotatory bending fatigue (RBF) fatigue strength ( ) and a 3‐timeslonger RCF L 10 life. The crescent‐shaped granular bright facet (GBF) zone, normally found in high‐strength steels' very high cycle fatigue regimes beyond 10 7 cycles normally under a much lower stress amplitude, appears around inner inclusions on the CSR + VAR steel RBF fracture surfaces in high cycle fatigue regimes beyond 3 × 10 5 cycles. The development of GBF zones is estimated to account for 79%–90% of the RBF fatigue life. The average crack propagation rate (da/dN) for GBF zones varies from 1.3 × 10 −12 m/cycle to 24 × 10 −12 m/cycle and increases with the stress amplitude.