Effect of trace element arsenic on the high cycle fatigue properties and the carbide uniformity in high carbon chromium bearing steel

Abstract

In this paper, the mechanical properties and microstructures of bearing steels with arsenic contents of 30, 40, and 120 ppm have been investigated. The results show that As-40 steel has the highest tensile strength but lower fatigue strength than As-120 steel. The fatigue crack propagation rate of As-120 steel is relatively low, mainly due to the increase in ΔK_th. After quenching and tempering, As-120 steel has larger prior austenite grains and more undecomposed, elongated carbides appear, reducing the uniformity of the steel. For carbides with an aspect ratio greater than 2, they cannot grow by the Oswald mechanism of spontaneous migration but are spheroidized by self-cracking. The undissolved elongated carbides have a lower chemical potential, which increases the diffusion tendency of arsenic in the matrix. SIMS and EPMA analyses show that there is no significant distortion of the trace element arsenic.