多次切割轮廓法测试局部补焊厚板内部残余应力分布

Measurement on the Internal Stress Distribution in a Thick Specimen with a Patrial Repair Weld Using Mutiple-cut Contour Method

局部修补焊缝的应力分布呈现三维特征,需要进行内部应力测试才能全面反映局部补焊对焊接残余应力的影响。采用多次切割轮廓法测试50mm厚局部补焊试板的内部应力分布,获得原始焊缝位置的纵向应力、补焊位置的纵向应力以及原始焊缝中心位置的横向应力分布;分析补焊焊接对纵向焊接应力的影响;研究了试板中截面位置横向切割后造成的应力释放程度。结果表明,多次切割轮廓法可获得试样不同位置的横向和纵向应力分布全貌;局部补焊造成补焊焊缝内的纵向应力幅值增加,峰值应力相对原始焊缝增加30%;由于局部补焊焊缝的热处理作用,其上部区域的纵向应力降低,峰值应力相对原始焊缝降低幅度达到60%;垂直焊缝方向平行切割测试两位置的纵向应力时,两切割面的距离大于2倍厚度,第一次切割对第二次切割面上的应力状态影响较小。多次切割轮廓法为研究厚板内部应力局部补焊前后的变化提供了经济高效的测试手段。

Residual stress distributions in partial repair welds exhibit 3-D characteristics. It is necessary to perform measurement on internal stresses to investigate the effects of partial repair on welding residual stresses. The internal stress distributions in a 50 mm-thick specimen with a partial repair weld are measured by the contour method with multiple cuts, and the longitudinal and transverse stress distributions in the initial weld, the longitudinal stress distribution in the repair weld are obtained. The effect of the partial repair weld on the welding longitudinal stress distribution is studied. The extent of stress release induced by the transeverse cut at the middle-length location is also investigated. Investigated results show that the full maps of the welding longitudinal and transverse stress distributions can be obtained by the multiple-cut contour method;the peak longitudinal stress within the repair weld increases by 30% as compared with that in the initial weld;due to the heat effect exerted by the multipass welding of the repair weld, the peak longitudinal stress in the region above the partial repair weld decreases by 60% in relation to the peak stress in the initial weld;the extent of stress release caused by the transverse cut changes with the location from the cut edge, the stress within the region with a distance from the cut adge over twice times the thickness is almost unaffected by the cut. The multiple-cut contour method provides an economical and efficient method to investigate the variation of internal stress distribution in a thick welded plate before and after partial repair.