静态拉伸载荷下焊接残余应力演变规律

Research on the variation rule of welding residual stress under static load tensile stress

静态工作应力与焊接残余应力叠加,将导致构件产生局部塑性变形以及焊接残余应力重新分布,静态工作应力卸载后,可以降低残余应力峰值。基于此理论,选用A6005A-T6铝合金焊接接头作为研究对象,研究静态加载条件和逐级加载条件下残余应力的演变规律。结果表明:平板焊接试板经过静态拉伸(加载载荷150 MPa)后残余应力发生了很大程度的释放,纵向残余应力峰值由125 MPa降为48 MPa,横向残余应力峰值由155 MPa降为56 MPa。这是因为外载与残余应力叠加超过材料屈服强度产生了塑性变形,残余应力发生释放。焊接构件使用前可以进行一定程度的静拉伸,从而消除一部分残余应力,尤其是降低残余应力的峰值。

The local plastic deformation and redistribution of residual stress would occur under the superposition of static load stress and welding residual stress. The peak residual stress will decrease alter the static stress unloaded. This paper was based on this theory and took A6005A-T6 aluminum alloys welded joints as the objectives to study the static loading conditions and gradual loading conditions under the evolution of residual stress. The results showed that the residual stress had relaxed in high degree after static load stress（the loading stress was 150 MPa）,the peak value had changed from 125 MPa to 48 MPa of the longitudinal residual stress and the peak value had changed from 155 MPa to 56 MPa of the transverse residual stress. The reason was that the residual stress had relaxed due to the superimposion of external load and residual stress beyond the yield strength of the material had been plastic deformation. The welded structures could be statically stretched in some degree before using and could remove some residual stress especially the peak residual stress.