Effect of deformation modes and heat treatment on microstructure and impact property restoration of internal crack healing in SA 508 steel
Effect of deformation modes and heat treatment on microstructure and impact property restoration of internal crack healing in SA 508 steel
复制标题
变形方式和热处理对SA 508钢内部裂纹愈合组织和冲击性能恢复的影响
DOI：
10.1016/j.msea.2020.139073
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发表时间：
2020-03-19
期刊：
影响因子：
6.4
通讯作者：
Ma, Qingxian
中科院分区：
文献类型：
--
作者：
Qiu, Yao;Xin, Ruishan;Ma, Qingxian
在本研究中，研究了变形方式和淬火回火工艺对裂纹愈合和冲击性能恢复百分比的影响。对裂纹区在不同愈合阶段的显微组织、夏比冲击性能和断口形貌进行了评价。当修复温度为950℃和1050℃时，多道次热变形（2次镦粗1次拉拔）修复内部裂纹的冲击性能恢复百分比低于单轴压缩修复。经1150℃2次镦粗1次拉伸变形后，裂纹愈合区出现了新形成的“Z型”晶粒带，具有较高的抗动载荷能力。Q&T处理后，组织演变为回火贝氏体，残余奥氏体逐渐分解为碳化物，主要沿晶界析出。Q&T处理后，裂纹愈合区的冲击韧性有所提高，但回复率下降，这是因为在裂纹愈合区，碳化物呈直线聚集，其抗外力能力低于基体。
In this study, the effects of deformation modes and quenching and tempering (Q&T) process on the crack healing and percentage recovery of impact properties were studied. The microstructure, Charpy impact properties and fracture surface morphology of the crack zones at different healing stages were evaluated. When the healing temperatures was 950 degrees C and 1050 degrees C, percentage recovery of impact properties of the internal crack healing by multi-pass thermal deformation (twice upsetting and once drawing) was lower than that by uniaxial compression. After deformed by twice upsetting and once drawing at 1150 degrees C, the 'Z type' newly formed grain belt was observed in the crack healing zone, which showed high resistance to the dynamic load. After Q&T process, the microstructure was evolved into the tempered bainite, and residual austenite decomposed gradually to carbides, precipitating out mainly along the grain boundaries. After Q&T process, the impact toughness of the crack healing zones were improved, but the percentage recovery decreased, it is because that in the crack healing zone, the carbides aggregated in the line, which has a lower resistance to applied force than the matrix.