Dislocation density and sub-grain size evolution of 2CrMoNiWV during low cycle fatigue at elevated temperatures

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• 作者：T. Mayer^a ; ^{thomas.mayer@empa.ch} ; ^{mayert@student.ethz.ch} ; L. Balogh^b ; C. Solenthaler^c ; E. Mü ; ller Gubler^c ; S.R. Holdsworth^a
• 关键词：Dislocation density ; Sub-grain size ; Neutron diffraction ; Low cycle fatigue ; TEM
• 刊名：Acta Materialia
• 出版年：2012
• 期刊代码：1_13596454
• 类别：ms
• 出版时间：April, 2012
• 卷：60
• 期：6-7
• 页码：2485-2496
• 文件大小：2304 K

摘要

We present the dislocation density and sub-grain size evolution for samples subjected to low cycle fatigue (LCF) loading under various conditions. Interrupted LCF tests have been performed on a cyclic softening bainitic steam turbine rotor steel, 2CrMoNiWV, at total strain amplitudes of 卤0.25%, 卤0.4%and 卤0.7%, strain rates of 0.01 and 0.1% s^鈭?, and temperatures of 500 and 565 掳C. Neutron diffraction experiments have been carried out on these samples, which were evaluated by means of a convolutional multiple whole profile peak shape analysis approach. With this analysis, both dislocation density and sub-grain size evolutions have been determined and compared to the results of transmission electron microscopy (TEM) and scanning TEM (STEM) spot-check evaluations. In addition, the proportions of prevailing dislocation types and the correlation factor of the microstructure have been determined. Finally, the results have been used to establish a phenomenological model describing the relationships between the observed cyclic softening and the evolution characteristics of dislocation density and sub-grain size, as a function of strain amplitude, strain rate and temperature.