690镍基合金焊缝失塑裂纹产生的力学机制  

Formation mechanism of ductility dip cracking in 690 nickel-based alloy weld

作　　者：朱亮[1] 姚文选 

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,兰州730050

出　　处：《焊接学报》2017年第12期9-13,共5页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(51264026)

摘　　要：为了从力学角度理解镍基合金焊丝ERNi Cr Fe-7和ERNi Cr-4焊缝失塑裂纹的产生机制,在Thermorestor-W型模拟试验机上进行高温拉伸试验,提出新的裂纹敏感性判据——临界应力.并与产生裂纹的临界应变相结合来评价不同温度下材料的裂纹敏感性.结果表明,裂纹扩展的方向与加载方向大约呈90°夹角;当变形温度低于950℃时,临界应力随变形温度的升高而快速下降;两种材料产生裂纹最敏感的温度区间是950~1 150℃;与ERNi Cr-4相比,ERNi Cr Fe-7产生裂纹的临界应力更小.分析认为,流变应力是产生裂纹的主要因素,当流变应力超过临界应力时,容易产生沿晶裂纹.To understand the generation mechanism of crack in weld made with nickel base alloy welding wire ERNiCr Fe-7 and ERNi Cr-4 from mechanical point,high temperature tensile tests were carried out on Thermorestor-W simulation test machine,and a new crack sensitivity criterion-threshold stress was put forward. The crack sensitivity under various temperatures was evaluated by combining with threshold strain. The results showed that the degree between the crack propagation direction and loading direction was about 90°. When the deformation temperature was below 950 ℃,the threshold stress decreased fast with the increase of temperature. The most sensitive deformation temperature range for two wires to produce crack was 950-1 150 ℃. Compared with ERNi Cr Fe-4 wire,the threshold stress for cracks with ERNi Cr-7 wire was smaller. The flow stress was the main factor to produce crack. When the flow stress exceeded the threshold stress,intergranular crack easily formed.

关 键 词：镍基合金 高温失塑裂纹 临界应力 流变应力 

分 类 号：TG422.3[金属学及工艺—焊接]