文献类型：期刊文献

英文题名：Fatigue life and mechanistic modeling of interior micro-defect induced cracking in high cycle and very high cycle regimes

作者：Zhu, Ming-Liang[1];Jin, Long[1];Xuan, Fu-Zhen[1]

机构：[1]East China Univ Sci & Technol, Sch Mech & Power Engn, Minist Educ, Key Lab Pressure Syst & Safety, Shanghai 200237, Peoples R China

年份：2018

卷号：157

起止页码：259

外文期刊名：ACTA MATERIALIA

收录：;EI(收录号：20183005599825);WOS:【SCI-EXPANDED(收录号:WOS:000445318800023)】；

基金：The authors are grateful for the support provided by the National Natural Science Foundation of China (51575182). Thanks are due to Dr Jun Jiang at Imperial College London and Dr Yanzhong Tian at Institute of Metal Research, Chinese Academy of Sciences, for proof reading the paper, and Prof Jie Tong at University of Portsmouth, UK, for helpful discussions. The authors also appreciate the support by Bruker (Beijing) Scientific Technology Co., Ltd for microstructural analyses based on EBSD technique and the help from Mr Di Wan at Norwegian University of Science and Technology (NTNU) for texture interpretation.

语种：英文

外文关键词：Dislocation structures; Fatigue crack initiation; Focused ion beam (FIB); Microstructure-inclusion interaction; Very high cycle fatigue

摘要：Axially loaded push-pull cyclic tests of a precipitation-hardened stainless steel with different sampling orientations were conducted in high cycle and very high cycle fatigue regimes. Results showed apparent fatigue anisotropy with non-metallic inclusions dominating crack initiation behavior. A fatigue lifing model was developed by combining size, location and shape of inclusions into a new form of Z parameter to rationalize the orientation effect. Using a multi-scale and full-field approach, the inclusion-induced interior cracking mechanisms were found to be associated with inclusion-microstructure interaction resulted plasticity. Micro-hardness at the cracking site was the lowest on the fracture surface, and surrounding microstructures showed formation of small grains with clear interfaces. The fine granular area was characteristic of several nano-scale fine grains formed in terms of dislocation cell structures by martensitic laths breakdown. The coalescence of interfaces or micro-crackings finally became interior early fatigue cracks. The mechanistic modeling of "fragmentation of martensitic laths and formation of dislocation cells" revealed a microstructure-dependent crack initiation and stage I growth for interior fatigue cracking. All these inform the significance of combining metallurgical and processing factors in designing against fatigue of engineering materials. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.