TC4钛合金机匣焊接残余应力VSR调减工艺研究

Study on VSR Reduction Technology of Welding Residual Stress in TC4 Titanium Alloy Casing

某发动机的TC4钛合金机匣外环与叶片的焊缝处残余应力梯度大且分布复杂,严重降低了机匣的疲劳寿命。基于机匣部件的模态振型特征和应变量设计了等效试件,研究振动时效方法调减机匣焊接残余应力的可行性和工艺参数。根据机匣部件的模态特征设计等效工艺试验模型,基于机匣和工艺试验模型的应变振型确定等效试件的VSR激振频率和装夹方式,采用X射线衍射法测量试件表面应力以评价VSR应力调减效果。结果表明:VSR处理后焊接接头表面残余应力峰值最高下降了30.8%,应力匀化率最高达到41.8%,所设计的振动工艺参数可用于机匣焊接残余应力的调减和匀化。

Large in size and complex for its distribution,the residual stress gradient at the welding seam between the outer ring and blade of a TC4 titanium alloy casing of an engine severely reduces the fatigue life of the casing.Based on the modal shape characteristics and strain variables of casing components,equivalent specimens were designed,and the feasibility and technological parameters of vibration stress relief method for reducing welding residual stress of casing were studied.An equivalent process test model was designed according to the modal characteristics of the casing components.Based on the strain mode patterns of the casing and process test model,the VSR excitation frequency and clamping mode of the equivalent specimens were determined.The surface stress of the specimens was measured by X-ray diffraction method to evaluate the VSR stress reduction effect.The results show that after VSR treatment,the peak value of residual stress on the welded joint surface decreases by 30.8%in maximum,and the stress homogenization rate reaches 41.8%in maximum.Therefore,the designed vibration process parameters can be used to reduce and homogenize the residual stress on the casing welding.