An investigation into the evolution of temperature and stress fields, as well as the phase transformation in marine steel EH36 during multi-pass welding, and their subsequent effects on Charpy impact toughness, remains in great lack. In this study, submerged arc welding (SAW) was employed to carry out multi-pass welding on EH36 steel plates, followed by the low-temperature toughness test of weldments. Comsol software version 6.2 and finite element analysis are utilized to simulate the evolution of the microstructure, temperature, and residual stress fields throughout the multi-pass welding process. As welding progressed, the heat absorption along the vertical direction was enhanced; in contrast, a decrease is observed in the horizontal direction away from the heat source. This complicated temperature history favors the bainite transformation in the vicinity to the heat source, whereas areas more remote from the weld zone exhibit a higher prevalence of acicular ferrite due to the reduced cooling rate. The concentration of residual stress is predicted to occur at the boundary of the melt pool and at the interface between the weld and the heat-affected zone, with the greatest deformation observed near the fusion line at the top surface of the model. Furthermore, multi-pass welding may alleviate the residual stress, especially when coupled with the formation of acicular ferrite upon cooling, leading to improved low-temperature impact toughness in regions remote from the heat source. These findings offer valuable insights for the design and optimization of multi-pass welding in future applications.

中文翻译：

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EH36船用钢多道焊接过程中温度演变、固相变和残余应力分布的数值模拟

对温度场和应力场的演变以及船用钢 EH36 在多道焊接过程中的相变及其对夏比冲击韧性的后续影响的研究仍然非常缺乏。本研究采用埋弧焊（SAW）对EH36钢板进行多道焊，并对焊件进行低温韧性试验。利用 Comsol 软件 6.2 版和有限元分析来模拟整个多道焊接过程中微观结构、温度和残余应力场的演变。随着焊接的进行，沿垂直方向的吸热增强；相反，在远离热源的水平方向上观察到减少。这种复杂的温度历史有利于热源附近的贝氏体转变，而距离焊接区更远的区域由于冷却速率降低而表现出针状铁素体的普遍存在。预计残余应力集中发生在熔池边界以及焊缝与热影响区之间的界面处，在模型顶面的熔合线附近观察到最大变形。此外，多道焊接可以减轻残余应力，特别是当与冷却时针状铁素体的形成相结合时，从而提高远离热源的区域的低温冲击韧性。这些发现为未来应用中多道焊接的设计和优化提供了宝贵的见解。