P91 steel belongs to martensitic heat-resistant steel. Solid phase transformation (SPT) during welding will affect temperature field and stress field. In this paper, a method for calculating welding residual stress of P91 steel considering martensitic transformation is proposed by using finite element (FE) software ABAQUS and self-compiled user subroutines. The methods of reducing residual stress are analyzed through the preheating, changing the starting temperature of martensitic transformation and controlling the interlayer temperature. It is found that the Mises stress decreases and the low stress area at the weld bead enlarges after preheating. Within a certain range, the Mises stress value can be reduced by decreasing the starting temperature of martensitic transformation. The starting temperature of martensitic transformation is suggested to be 325 °C. Within a certain range, increasing interlayer temperature can enlarge the low Mises stress area, increase the longitudinal compressive residual stress and reduce the transverse residual tensile stress. The highest interlayer temperature should not exceed 315 °C.

P91钢属于马氏体耐热钢。焊接过程中的固相转变（SPT）会影响温度场和应力场。本文利用有限元软件ABAQUS和用户自编的子程序，提出了一种考虑马氏体相变的P91钢焊接残余应力计算方法。分析了通过预热、改变马氏体相变起始温度和控制层间温度来降低残余应力的方法。发现预热后Mises应力降低，焊道低应力区扩大。在一定范围内，降低马氏体转变起始温度可以降低Mises应力值。建议马氏体转变的起始温度为 325 °C。在一定范围内，提高层间温度可以扩大米塞斯低应力区，增加纵向残余压应力，降低横向残余拉应力。最高层间温度不应超过 315°C。