Abstract:  A multi-pass butt-welded joint of low alloy high strength steel Q960E was prepared by equal strength matching wire and mixed gas shielded welding method. Microstructure， hardness distribution， welding temperature cycles， welding deformation and welding residual stress were observed and measured by experiments. With the consideration of the microstructure characteristics of Q960E， a thermal-elastic-plastic finite element method which considered the coupling behaviors among multiple physical fields of “thermal-microstructure-stress” was developed based on SYSWELD software platform. The material model focused on solid-state phase transformation in the heat-affected zones（HAZs）. The JMAK equation was employed to describe the austenitization processes during the heating stages， while the K-M equation was utilized to simulate the martensitic transformation processes in the cooling stages. At the same time， the transformation-induced plasticity in the cooling processes was considered based on the Leblond model. The comparison between the numerical simulation results and the experimental measurements shows that both the residual stress distribution and the welding deformation obtained by the finite element model are in a good agreement with the measured data， and the numerical simulation results also show that the solid-state phase transformation has a significant effect on the distribution and magnitude of welding residual stress in the HAZ of Q960E steel butt-welded joints. 

Key words:  , Q960E steel, welding deformation, residual stress, solid-state phase transformation, numerical simulation

摘要： 利用等强匹配焊丝和混合气体保护焊方法制备了Q960E低合金高强钢的多层多道对焊接头。采用实验法测量了焊接温度循环、焊接变形以及焊接残余应力，同时观察了焊接接头的微观组织，并测量了硬度分布。基于焊接接头的组织特征，以SYSWELD软件为平台，开发了考虑“热-组织-应力”多物理场耦合的热-弹-塑性有限元计算方法。重点考虑了热影响区的固态相变材料模型，采用JMAK方程描述加热阶段的奥氏体化过程，采用K-M关系模拟冷却阶段的马氏体相变过程，同时基于Leblond模型考虑了冷却过程中的相变诱导塑性。数值模拟结果与实验测量结果的对比表明，有限元模型得到的残余应力分布和焊接变形与实测数据吻合较好，同时数值模拟结果还证明了固态相变对Q960E钢对接接头热影响区的残余应力分布与大小均有显著的影响。

关键词: Q960E钢, 焊接变形, 残余应力, 固态相变, 数值模拟