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Stress state and stress‐induced microstructural evolution around the crack tip of G115 steel after dwell‐fatigue crack propagation
Author(s) -
Tang Zhengxin,
Jing Hongyang,
Xu Lianyong,
Zhao Lei,
Han Yongdian,
Xiao Bo,
Zhang Yu,
Li Haizhou,
Wu Dongquan
Publication year - 2019
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/ffe.13051
Subject(s) - materials science , crack closure , creep , dislocation , stress (linguistics) , martensite , composite material , stress concentration , transmission electron microscopy , fracture mechanics , metallurgy , structural engineering , microstructure , nanotechnology , linguistics , philosophy , engineering
Many components operate under creep‐fatigue loading causing an increasing need to learn the knowledge about creep‐fatigue crack growth (CFCG). The stress and microstructural evolution around the crack tip of G115 steel after CFCG were investigated. According to the finite element simulations, the variations of equivalent stress and stress triaxiality in the crack tip zone are presented. Furthermore, the evolutions of martensitic laths, dislocations, and precipitates were systematically studied through electron backscatter diffraction and transmission electron microscopy observations. The laths at the crack tip or under a larger hold time are wider than those remote from the crack tip or under a shorter dwell time. Meanwhile, the dislocation densities reduced significantly at the crack tip or under a larger hold time. The different variations of laths' width and dislocation densities resulted from the different stress triaxiality and creep strain. W‐rich Laves and Cu‐rich phases appeared during CFCG. The Laves phase coarsened rapidly because of the stress‐accelerated diffusion.