Cyclic softening of martensitic steels at high temperature—Experiments and physically based modelling
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- 作者：Maxime Sauzay ; Benjamin Fournier ; Michel Mottot ; André ; Pineau ; Isabelle Monnet
- 关键词：Creep-fatigue ; Martensitic steel ; Cyclic softening ; Microstructure evolution ; Low-angle boundary ; Climb
- 刊名：Materials Science and Engineering: A
- 出版年：2008
- 出版时间：15 June 2008
- 年：2008
- 卷：483-484
- 期：Complete
- 页码：410-414
- 全文大小：443 K
文摘
Martensitic steels subjected to cycling at high temperature usually show softening accompanied by microstructural changes such as the disappearance of low-angle boundaries (LABs). A micromechanical model of the disappearance of LABs due to annihilation between mobile impinging dislocations and LAB dislocations has been recently proposed [M. Sauzay, H. Brillet, I. Monnet, M. Mottot, F. Barcelo, B. Fournier, A. Pineau, Mater. Sci. Eng. A 400–401 (2005) 241–244]. This model is, however, unable to accurately reproduce viscoplastic strain amplitude and hold time effects, while these effects are clearly observed. Considering that there is not a complete renewal of the (edge) mobile dislocations at each cycle, the lifetime of the mobile dislocations is introduced as well as a climb mechanism to describe more accurately the annihilation mechanisms. Using in addition the Hall–Petch modelling proposed by Li, stress softening predictions are discussed with respect to experimental results.