Near-threshold fatigue crack propagation without oxide-induced crack closure

Koki Tazoe; Hiroto Tanaka; Masanori Oka; Genki Yagawa

doi:10.1038/s41598-020-64915-3

Near-threshold fatigue crack propagation without oxide-induced crack closure

Sci Rep. 2020 May 13;10(1):7926. doi: 10.1038/s41598-020-64915-3.

Authors

Koki Tazoe¹, Hiroto Tanaka², Masanori Oka², Genki Yagawa³

Affiliations

¹ Research and Development Center, YANMAR HOLDINGS CO., LTD., 2481, Umegahara, Maibara, Shiga, 521-8511, Japan. koki_tazoe@yanmar.com.
² Research and Development Center, YANMAR HOLDINGS CO., LTD., 2481, Umegahara, Maibara, Shiga, 521-8511, Japan.
³ University of Tokyo and Toyo University, c/o Toyo University, Kawagoe, Saitama, 350-8585, Japan.

Abstract

An accurate value for the threshold stress intensity factor range, ΔK_th, is a key parameter for studying crack-like defects. However, it is difficult to obtain accurate ΔK_th values due to oxide-induced crack closure. In this study, we report conditions for minimizing the effects of oxide-induced crack closure near the threshold region, where a concave curve of the effect on the loading frequency on oxide-induced crack closure is achieved. The resulting conditions allow for an accurate determination of ΔK_th, which is a key material parameter relating to the pertinent loading ratio.