Combined quantitative evaluation on early-stage fatigue damage of coarse-grained austenite stainless steel based on EBSD and ultrasonic technique

Zhongbing Luo; Xinyu Wang; Zhiyuan Ma; Longjiang Zou; Xiaolei Zhu; Li Lin

doi:10.1016/j.ultras.2020.106090

Combined quantitative evaluation on early-stage fatigue damage of coarse-grained austenite stainless steel based on EBSD and ultrasonic technique

Ultrasonics. 2020 Apr:103:106090. doi: 10.1016/j.ultras.2020.106090. Epub 2020 Jan 30.

Authors

Zhongbing Luo¹, Xinyu Wang¹, Zhiyuan Ma¹, Longjiang Zou¹, Xiaolei Zhu¹, Li Lin²

Affiliations

¹ NDT & E Laboratory, Dalian University of Technology, Dalian 116085, China.
² NDT & E Laboratory, Dalian University of Technology, Dalian 116085, China. Electronic address: linli@dlut.edu.cn.

PMID: 32044569
DOI: 10.1016/j.ultras.2020.106090

Abstract

The elastic anisotropy and heterogeneity effects of coarse-grained austenite on ultrasonic propagation significantly undermine the effectiveness of ultrasonic property-based fatigue damage evaluation. A discrete method based on electron backscatter diffraction (EBSD) was proposed to decouple the effects between coarse-grained structure and fatigue damage. An orientation-based damage index, local misorientation (M_L), was extracted and macroscopic and microscopic plastic deformations were characterized. The evolution of ultrasonic attenuation coefficient Δα was established with ΔM_L in grain scale. Approximate downward parabolas was observed, and the peak value of Δα in 〈1 1 1〉 orientation was found to be larger and more sensitive to the cyclic damage than that of 〈0 0 1〉 and 〈0 1 1〉. The influences of the heterogeneous substructure and surface roughness were discussed respectively.

Keywords: Coarse-grained austenite; Electron backscatter diffraction; Fatigue damage; Grain scale; Ultrasonic.