低合金钢焊接热影响区的微观组织和韧性研究进展

对钢结构而言,诸如海洋平台、船舶、桥梁、建筑和油气管线等,焊接后的性能直接决定了其服役寿命和安全性,重要性不言而喻.在针对焊接相关问题的研究中,焊接热影响区的韧性提升一直是重点和难点.焊接热影响区会经历高达1400℃的高温,从而形成粗大的奥氏体晶粒,如果焊接参数控制不当,不能通过后续冷却过程中的相变细化组织,就会造成韧性的降低.而多道次焊接的情况更为复杂,前一道次形成的粗晶区还会在后续焊接过程中经历二次热循环,从而形成链状M-A,造成韧性的急剧下降.本文旨在对一些现有焊接热影响区的相关研究结果进行总结,探讨母材的成分、第二相及焊接工艺等因素对热影响区微观组织和性能的影响,为低温环境服役的大型钢结构的焊接性能改善提供一些设计思路.

Research progress on microstructures and toughness of welding heat-affected zone in low-alloy steel

The welding performance of steel structures such as offshore platforms, ships, bridges, buildings, and oil and gas pipelines directly determines the service life and safety of the structure, the importance of which cannot be minimized. In welding-re-lated research, the toughness of the welding heat-affected zone is a key issue. This zone experiences temperatures as high as 1400℃, thereby causing the formation of coarse austenite grains. If the welding parameters are improperly controlled, microstructure refinement cannot be achieved by subsequent phase transformation, which results in decreased impact toughness. Multi-pass welding is even more complex, with the secondary heat input affecting the coarse-grain zone formed during the previous pass. This results in the formation of necklace-type M-A constituents, which also lead to deterioration in toughness. In this paper, the relevant research results were sum-marized with regarding the welding heat-affected zone and it was discuss that the composition of the parent material, the second phase, the welding process, and other factors effect the microstructures and properties of the heat-affected zone. This paper also offers ideas for improving the welding performance of large steel structures in low-temperature service circumstances.