Dislocation density and sub-grain size evolution of 2CrMoNiWV during low cycle fatigue at elevated temperatures
Dislocation density and sub-grain size evolution of 2CrMoNiWV during low cycle fatigue at elevated temperatures
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DOI：
10.1016/j.actamat.2011.12.031
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发表时间：
2012-04
期刊：
影响因子：
9.4
通讯作者：
T. Mayer;L. Balogh;C. Solenthaler;E. Gubler;S. Holdsworth
中科院分区：
文献类型：
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作者：
T. Mayer;L. Balogh;C. Solenthaler;E. Gubler;S. Holdsworth
研究了不同条件下低周疲劳（LCF）载荷下的位错密度和亚晶粒尺寸演变。在循环软化贝氏体汽轮机转子钢2CrMoNiWV上进行了间断LCF试验，总应变幅为±0.25%、±0.4%和±0.7%，应变率为0.01和0.1%s - 1，温度为500和565℃。对这些样品进行了中子衍射实验，并用卷积多重全剖面峰形分析方法对样品进行了评价。通过这种分析，确定了位错密度和亚晶粒尺寸的演变，并将其与透射电子显微镜（TEM）和扫描电子显微镜（STEM）抽查评估的结果进行了比较。此外，还确定了主要位错类型的比例和微观组织的相关系数。最后，利用实验结果建立了一个描述循环软化与位错密度和亚晶粒尺寸随应变幅值、应变速率和温度变化关系的唯象模型。
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 ±0.25%, ±0.4% and ±0.7%, strain rates of 0.01 and 0.1%s−1, and temperatures of 500 and 565°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.