摘要
基于攻关华龙一号及在役核电机组关键核心技术装备,将EQ NiCrFe-7A焊带熔覆金属作为研究对象,以了解高温服役状态下镍基690合金的组织及裂纹敏感性变化。采用应变-裂纹试验(Strain-To-Fracture)、扫描电子显微镜表征了不同温度下材料的裂纹敏感性及微观组织演变。结果表明,EQ NiCrFe-7A焊缝金属的高温失塑裂纹敏感性随温度升高而降低,裂纹敏感温度区间为950℃~1050℃,最低临界应变量为4.21%。高温失塑裂纹的开裂受晶界形态和析出相分布影响,随温度升高,大角度晶界比例升高,残余应力增加,析出相钉扎作用减弱,高温失塑裂纹开裂倾向增加。裂纹附近富集的残余应力,能促进再结晶晶粒和孪晶的产生,一定程度上缓解了裂纹扩展。
Based on the key core technology of Hualong-1 and in-service nuclear power units,the EQ NiCrFe-7A weld metal was taken as the research object to understand the change of the microstructure and crack sensitivity of Ni-based 690 alloy in high temperature service.The crack sensitivity and microstructure evolution of the material at different temperatures were characterized by strain-to-fracture test and scanning electron microscopy.The results show that the high temperature ductility-dip crack sensitivity of EQ NiCrFe-7A weld metal decreases with the increase of temperature,and the crack sensi‐tivity temperature range is 950℃-1050℃,with the minimum critical strain of 4.21%.The high temperature ductility-dip crack is affected by the grain boundary morphology and the distribution of precipitated phases.With the increase of tempera‐ture,the proportion of large-angle grain boundaries increases,the residual stress increases,the pinning effect of precipitated phases weakens,and the high temperature ductility-dip crack tendency increases.The residual stress enriched near the crack can promote the recrystallization grain and twin,and fasten the crack propagation to some extent.
作者
孟长鑫
曹睿
杨飞
徐晓龙
王若蒙
蒋勇
MENG Changxin;CAO Rui;YANG Fei;XU Xiaolong;WANG Ruomeng;JIANG Yong(State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metal,Lanzhou University of Technology,Lanzhou 730050,China;Atlantic China Welding Consumables,INC.,Zigong 643000,China)
出处
《电焊机》
2025年第8期68-73,99,共7页
Electric Welding Machine
基金
甘肃省科技重大专项(22ZD6GA008)
国家自然科学基金(52175325)
国家自然科学基金(51961024)
国家自然科学基金(52071170)。
关键词
EQ
NiCrFe-7A焊缝金属
应变-裂纹试验
晶界特征
高温失塑裂纹
EQ NiCrFe-7A weld metal
strain-to-fracture test
grain boundary characteristics
high temperature plastic defor‐mation crack
