分段焊影响转轮焊接残余应力的试验分析

在利用平板试验得到分段焊的合理段长的基础上,对某水电站混流式水轮机转轮的焊接残余应力场进行了调控.结果表明,对于尺寸为500 mm×500 mm×16 mm的平板来说,后焊的焊段可以起到降低先焊焊段的残余应力的作用,且在到后焊部分端部为50 mm的范围内,降低效果最明显;分段焊可以降低叶片危险区域的残余拉应力峰值并产生残余压应力;当叶片出水边焊段的长度在40～90 mm的范围内,残余应力的降低效果随着叶片出水边焊段长度的增加而减小.

Experimental research on subsection welding effect on runner welding residual stress

On basis of subsection welding'' s reasonable section length attained by plane plate experiment, regulating and controlling on some hydroelectric station runner welding residual stress field is researched by means of subsection welding.The result shows for the plane plate whose dimension is 500 mm ×500 mm ×16 mm, the latter welding part can decrease welding residual stress of the prior welding part and the decreasing effect is obvious when the distance is less than 50 mm away form the end of latter welding part;subsection welding can effectively decrease welding tensile stress and then engenders residual transverse stress in the blade dangerous area. Moreover, when the welding section length of balde outlet is from 40 mm to 90 mm, the decreasing effect of residual stress is reducing with the welding section length'' s increasing of blade outlet.