大直缝焊管热时效与振动时效消应力工艺比较

采用热时效和振动时效两种工艺控制大型直缝焊管的焊接残余应力.结果表明,热时效和振动时效工艺均能有效降低Q345钢大型直缝焊管的残余应力,使焊接残余应力分布更加均匀,且焊接区的消应力效果相对于母材区更为明显.其中振动时效对铸态组织有良好的消应力作用,但对于冷塑性变形加工状的组织消应力效果不理想.热时效工艺的消应力效果和均化应力能力优于振动时效工艺,但在满足消应力要求的前提下考虑经济因素和工艺便捷性,最终选定振动时效作为消应力工艺.

Comparison of stress relief by PWHT and VSR in large-dimension straight welded pipe

Post-weld heat treatment (PWHT) and vibratory stress relieving (VSR) were used to control the residual stress in large-dimension welded pipes.The results show that both PWHT and VSR are able to relieve the residual stress effectively in large-dimension straight welded pipe and make the distribution of residual stress more uniform.Their effect in weld zone is more obvious than these in base metal.The results of stress relieving of VSR of as-cast microstracture are qualified but not acceptable in cold plastic deformation zone.The effect of PWHT on the stress relieving and stress uniform ability is better than that of VSR.However, considered of economy factor and technique convenience, VSR is confirmed as stress relieving technique to control the residual stress in large-dimension straight welded pipe.