钛合金薄板带热沉的TIG焊温度场

采用数值模拟和试验相结合的方法比较研究了钛合金薄板常规钨极氩弧焊(TIG)及带热沉的TIG焊焊接过程中温度场的形态与演变历史。相对于预置温度场的静态焊接应力和变形控制技术,带热沉的TIG焊接技术又称动态控制低应力无变形焊接技术(DC-LSND,Dynamically controlled low stress no-distortion)。该技术中。在热源之后紧随起冷却作用的热沉装置。研究结果表明。采用DC-LSND技术在热沉附近形成了中间低两边高的马鞍形温度场,热沉作用部位存在温度低谷,该温度区冷却收缩造成对附近高温区的拉伸作用,使焊缝不协调应变减小,焊缝中的残余拉应力降低,防止了焊接变形的产生。对DC-LSND畸变温度场的研究是了解这种方法控制变形机理的前提。

Temperature field of TIG welding with a spot heat sink of Ti alloy thin sheet

The temperature field and the temperature developing history were studied both numerically and experimentally for the conventional TIG welding and TIG welding with a spot heat sink of Ti alloy TC4.Comparing with the "static" control method,in which a temperature field was preset on workpieces,the TIG welding with a spot heat sink was also named dynamically controlled low stress no-distortion (DC-LSND) wel-ding technique,in which the arc was followed with a moving spot heat sink.The results showed that the saddle-backed temperature field was formed near the heat sink in DC-LSND TIG welding.There existed a low temperature region at the zone where the heat sink was applied.The contraction of this zone led to tensile action on the high temperature region nearby,which effectively reduced the incompatible strains and residual tensile stress in the weld,and prevented the occurrence of deformation.The research on the distorted temperature field of DC-LSND welding was the prerequisite to understand the mechanism of controlling deformation by this method.