轨道车辆转向架焊接构架多层深残余应力研究

Research of the residual stress at multi一layer depths of welded bogie frames for rail vehicles

为系统掌握多层深残余应力分布规律,综合采用X射线衍射法和超声波法,对焊接态、热处理态和喷丸态3种状态构架的焊缝表面及以下5.9 mm范围内多层深度的残余应力进行了综合测试研究。研究结果表明:焊接态构架呈现出“拉应力峰值-陡降-缓降-低值拉应力”的分段下降式分布规律;构架经热处理后,焊缝表面至以下0.85 mm共6种层深的残余应力均实现了均匀化分布;构架经喷丸处理后,表面至以下0.85 mm层深的残余压应力整体上呈“对勾状”分布,峰值出现在0.1 mm深度,0.85-1 mm深度后,拉应力缓慢下降,总体呈“不对称抛物线状”分布。提出了将研究成果在评价喷丸处理效果、辅助制定焊接及热处理工艺及评估焊接缺欠的影响等领域的应用启示。

In order to understand the stress distribution law at multi-layer depths,comprehensive tests are conducted on the residual stress at multi-layer depths of the weld surface and 5.9 mm below on the as-weld,as-heat treated and as-shot blasted frame by means of X-ray diffraction and ultrasonic methods.Test results show that as-weld frame demonstrates a distribution pattern of stepped decline of w peak tensile stress-sharp drop-slow descent-low tensile stress".After the heat treatment,the weld surface and 0.85 mm below on the bogie frame achieves an equalized distribution of residual stress at 6 layer depths.The residual compressive stress at the surface and 0.85 mm below on the frame generally exhibits a“double-hook-shaped”distribution after shot blasting,with the peak appearing at the depth of 0.1 mm,the tensile stress begins to decline slowly below the depth range of 0.85~1 mm,showing an w asymmetric parabolicM distribution on the whole.The paper finally proposes that the research achievements could be applied to the effect evaluation of shot blasting,supplementary formulation of welding and heat treatment processes and assessment of the impact of incomplete welding.