焊接顺序对混流式水轮机转轮焊接应力的影响

EFFECT OF WELDING SEQUENCE ON WELDING STRESS OF FRANCIS TURBINE RUNNER

在解决叶片与上冠或下环之间的热传导问题以及焊接热源沿任意空间路径移动的加载问题的基础上,对混流式水轮机转轮焊接过程的温度场与应力场进行了数值模拟。结果表明,叶片焊后残余拉应力场出现在焊缝及其附近区域,并且应力峰值出现在焊缝区域的叶片出水边处。同时,不同焊接顺序的转轮残余拉应力峰值的对比表明,焊缝两侧金属在焊接过程中填充的越均匀,残余拉应力的峰值越小。

Francis turbine runner＇s welding temperature field and stress field are simulated on basis of realizing the welding thermal source＇s movement along any complicated spatial route and solving the problem of heat conduction between blade and crown or band. The simulation result shows that welding residual tensile stress appears on the weld and nearby while the peak value of residual tensile stress appears on the blade＇s outlet edge of weld area. Moreover, the contrast of residual tensile stress between different welding sequences shows that the evener the filler metal of weld during the welding process is filled, the less the peak value of residual tensile stress is.