在1 230~1260℃温度范围内进行了T91钢管的加压瞬间液相连接,利用电子探针研究了焊接温度对接头组织、成分的影响.结果表明：随着连接温度的提高,合金元素在接头区扩散加剧,接头组织趋于均匀化,但在1 260℃的连接温度下,接头区出现孔洞.采用先加热到1 260℃短时保温再降至1 230℃长时保温的双温加热模式,不仅可减少焊缝区的缺陷,而且可消除连接界面,实现无缝连接.接头拉伸时在母材断裂,弯曲180°不断,性能达到母材水平.另外,与钎料压力焊接头相比,加压瞬间液相连接接头变形小,两连接管具有很好的同轴度.

T91 steel pipe was joined by transient liquid phase bonding under low pressure at 1 230-1 260℃,and the influence of bonding temperature on the microstructure and composition of the joints was investigated by EPMA.The results show that with increasing of the bonding temperature,the diffusion of alloying elements across the joint is accelerated and the homogenization of the joint microstructure is promoted.However,some cavities are produced in the joint when the bonding temperature arrives at 1 260℃.The two step heating process,which is that the joint is firstly heated up to 1 260℃ and keep for 5s and then cool to 1 230℃ and keep for 180 s,can not only reduce the defects,but also dismiss the bonding interface,producing a seamless joint.The joint fails in base metal and no failure occurs when it is tensioned and bended to 180° respectively,indicating that the joint mechanical properties arrive to the base metal.In contrast to braze press welding,the axes of pipes are not shifted to each other and only little deformation can be observed.