预变形对X80直缝埋弧焊管焊接接头残余应力及疲劳性能影响的模拟研究

Effect of pre-deformation on residual stress and fatigue life of weld joint of X80 LSAW pipe

本文采用数值模拟方法,通过预拉伸变形模拟钢管的扩径过程,分析了扩径变形对X80直缝埋弧焊钢管焊接接头残余应力分布的影响,进而分析残余应力对疲劳性能的影响。结果表明:模拟扩径拉伸变形后,因焊接热影响区的组织和性能变化及焊缝余高的作用,残余应力主要集中在焊接热影响粗晶区,其最大值出现在外焊缝焊趾的粗晶区。随变形量增加,残余应力也明显增大。当变形量由0.5%增加到4%时,外焊趾处最大残余应力由429 MPa增加到481 MPa。残余应力的增加显著降低疲劳性能,疲劳寿命最低值也出现在外焊缝焊趾处。与未变形试样的疲劳寿命相比,残余应力由429 MPa增加到481 MPa时,疲劳寿命损失率由18.0%增加到56.2%。

In this work,the effect of expending deformation on residual stress distribution of the weld joint of a X80 longitudinal-seam submerged arc welding(LSAW)pipe subjected to expending was analyzed by using number simulation applied tensile pre-deformation.Furthermore,the effect of the residual stress on fatigue properties was studied.Results show that the residual stress mainly concentrates in the coarse grain welding heat affected zone subjected to expending deformation because of the difference of microstructure and mechanical properties in heat affected zone and the effect of weld reinforcement,and the maximum residual stress occurs in coarse grain welding heat affected zone at outside weld toe.The residual stress increases with the increase of amount of deformation.As the deformation raises from 0.5%to 4%,the residual stress increases from 429 MPa to 481 MPa.The fatigue properties notably decreases with the increase of the residual stress.The minimum fatigue life also occurs at the outside weld toe.Comparing with the sample without deformation,as the residual stress raises from 429 MPa to 481 MPa,the fatigue life decreases 18.0%and 56.2%,respectively.