焊后热处理对P92钢管道焊接残余应力场的影响

Influence of heat treatment on residual stress of P92 steel pipe girth weld

采用红外热成像仪测量了P92钢管道在焊接过程中的温度场分布,由此获得P92钢焊接过程的温度循环曲线;采用有限元方法模拟了P92钢管道多层多道焊的整个焊接过程,获得焊接温度场分布,与P92钢焊接温度场实测结果吻合良好,验证了模拟计算的准确性;采用间接法,利用温度场结果计算了P92钢管道环焊缝焊接形成的残余应力场,并重点分析了焊后热处理前后的焊接残余应力变化情况.结果表明,焊后热处理对P92钢管道焊接残余应力具有明显的消除作用,但不能完全消除,焊缝中依然存在较大的拉伸残余应力.

Firstly, the welding temperature field of P92 steel pipe was measured with thermal imaging system, and the thermal cycles were achieved. Secondly, the finite element method (FEM) was utilized to simulate the welding process of P92 pipe girth weld, and to analyze the distribution of welding temperature in the welded joint. It was found that the simulation results had good agreement with the experimental results. Lastly, the simulated welding temperature field was used to calculate the residual stress of P92 steel pipe girth weld, and the emphasis was focused on the influence of the postweld heat treatment on the residual stress. The results showed that the postweld heat treatment could partially release the residual stress, while the comparatively large residual stress still survived in the weld joint. Therefore, the effect of residual stress must be considered in the life evaluation of P92 pipe.