混流式转轮局部处理技术与局部压应力区的优化

焊接残余压应力的存在能够有效提高焊接结构的抗疲劳性能．在优化混流式转轮焊接工艺、实现转轮叶片出水边焊接接头熔合区附近易开裂区域压应力化的基础上，对局部加热及锤击处理对转轮易开裂区域的应力场分布的影响进行了数值模拟和真机试验测试分析．结果表明，采用局部加热和局部锤击的方法均可以对转轮易开裂区域的焊接残余应力场进行调控，优化转轮的局部压应力区，进一步提高转轮易开裂区域的残余压应力值，形成高压应力区，扩大压应力区范围，促进转轮易开裂区域压应力化的实现，有效的提高转轮的抗疲劳性能．

Optimizing of compressive stress region by local treatment technologies on Francis runner

The existing of residual compressive stress increases the fatigue resistance of welding structures.The local compressive stress was realized around the fusion boundary in the Francis turbine runner by optimizing the welding process,where fracture could easily occur.And the influence of local heating and peening on the stress field in the fracture-easily-occurred region of runner was simulated and measured based on the real runner.The results indicate that the stress field in the fracture-easily-occurred region of runner can be regulated and controlled by local heating and peening processes.And the local compressive stress region was optimized.The value of residual compressive stress in the fracture-easily-occurred region of runner was further improved,and high compressive stress region was formed,especially,the compressive stress region was expanded.These processes can promote the realization of local compressive stress in the fracture-easily-occurred region of Francis runner and effectively enhance the fatigue resistance of the runner.