Ti_2AlNb合金电子束焊接接头的残余应力与再热裂纹  

Residual Stresses and Reheat Cracking of Ti_2AlNb Electron Beam Welded Joints

作　　者：吴爱萍[1] 李艳军[1,2] 赵玥 李权[3] 朱瑞灿[3] 刘磊[1] 邹贵生[1] 王国庆[4] WU Aiping;LI Yanjun;ZHAO Yue;LI Quan;ZHU Ruican;LIU Lei;ZOU Guisheng;WANG Guoqing(Department of Mechanical Engineering,Tsinghua University,Beijing 100084,China;Beijing Institute of Radio Measurement,Beijing 100854,China;Capital Aerospace Machinery Company,Beijing 100076,China;China Academy of Launch Vehicle Technology,Beijing 100076,China)

机构地区：[1]清华大学机械工程系,北京100084 [2]北京无线电测量研究所,北京100854 [3]首都航天机械公司,北京100076 [4]中国运载火箭技术研究院,北京100076

出　　处：《航空制造技术》2018年第8期26-35,共10页Aeronautical Manufacturing Technology

基　　金：航天科技一院高校联合创新基金项目(CALT201209;CALT201309)

摘　　要：利用数值分析和试验测量方法研究了不同板厚和不同形状Ti_2AlNb合金电子束焊接接头的焊接应力,分析了再热裂纹的产生特点和焊后热处理过程中的组织演变,讨论了再热裂纹产生的原因。结果表明,电子束焊缝中心部位承受3向拉应力,纵向残余拉伸应力最大,超过1100MPa;横向拉伸应力较小;板较薄时厚度方向残余拉伸应力也较小,但当焊接厚板时焊缝中心厚度方向的残余拉伸应力也很大,深窄焊缝中可达1000MPa。同样板厚条件下,环形焊缝与直线焊缝相比,周向拉伸应力略小于纵向应力,但径向拉伸应力远大于横向应力,尤其是环的直径较小时。再热裂纹的产生与再热过程中晶界析出物及较高的拉伸应力有关,在加热速度低于一定值,加热到700℃左右时,裂纹沿晶界析出层与基体之间的界面产生与扩展。The welding residual stresses were investigated with both experimental and numerical simulation methods,and the mechanism of the reheat cracking in Ti2AlNb EBW joint was also discussed with inspections on the characteristics of the cracks and the microstructures evolution during the heat treatments.The results showed that the EBW weld center suffered tensile stresses in three directions.The longitudinal tensile stress was the dominating tensile stress,which is more than 1100MPa,the tensile stresses in tansverse and thick directions had small values,except the plate is thick plate.Compared with the straight welds,the circular welds had lower hoop tensile stress,while higher radial tensile stress,especially in the small diameter circular weld.The formation of the reheat cracks was responsible to the precipitation layer at the grain boundary and the higher tensile residual stresses.The cracks were created and propagated along the interface between the precipitation layer and the matrix.The precipitation appeared when heating up to about 700°C with the heating rate below a critical value.

关 键 词：Ti2AlNb合金 电子束焊接 残余应力 再热裂纹 焊缝 

分 类 号：TG456.3[金属学及工艺—焊接]