Effect of thermal aging on grain structural characteristic and Ductile-to-Brittle transition temperature of CLAM steel at 550 °C
Effect of thermal aging on grain structural characteristic and Ductile-to-Brittle transition temperature of CLAM steel at 550 °C
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DOI：
10.1016/j.fusengdes.2016.12.037
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发表时间：
2017-02
影响因子：
1.7
通讯作者：
W. Wang;Wen Wang;Jianwei Chen;Gang Xu
中科院分区：
文献类型：
--
作者：
W. Wang;Wen Wang;Jianwei Chen;Gang Xu
利用电子背散射衍射（EBSD）技术研究了中国低活化马氏体（CLAM）钢在550 °C时效0 h、2000 h、4000 h和10,000 h后的晶粒结构演变。结果表明，随着时效时间的延长，原始奥氏体晶粒尺寸增大，晶界长度减小。热时效10,000 h后，在4 ° ~ 10°范围内的取向差比例明显增加，表明CLAM钢在长期热暴露过程中形成了细小的亚晶。此外，进行夏比冲击实验，以分析CLAM钢时效前后的韧性，特别是韧脆转变温度（DBTT）。虽然在基体中形成了大量细小的次晶，但在老化10，000 h后，DBTT（~ 40.1 °C）显著增加。结果表明，大角度晶界如原始奥氏体晶界比亚晶界更能有效地阻止解理裂纹的扩展。
In this work, electron backscatter diffraction (EBSD) was used to investigate the grain structure evolution of China low activation martensitic (CLAM) steel samples which were aged at 550 °C for 0 h, 2000 h, 4000 h and 10,000 h. The results showed that the prior austenitic grain size increased with the aging time, which led to the decrease of grain boundary length. The fraction of misorientation angle in a range from about 4 to 10° increased obviously after thermal aging for 10,000 h, and it indicated that the fine subgrains formed in the CLAM steel during the long-term thermal exposure. Furthermore, Charpy impact experiments were carried out to analyze the toughness of the CLAM steel before and after aging, particularly the Ductile-to-Brittle Transition Temperature (DBTT). Though amounts of fine subgrians formed in matrix, a substantial increase in DBTT (∼40.1 °C) had been noticed after aging for 10,000 h. The results showed that the high angle boundaries such as prior austenitic grain boundaries are more effective in retarding the propagation of cleavage crack than subgrain boundaries.