Q345/316L异种钢焊接接头显微组织结构与力学性能

Microstructure and mechanical properties of the Q345/316L dissimilar steel welded joints

利用气体保护钨极氩弧焊(GTAW),采用ER309L和ER308两种焊丝对Q345/316L异种钢进行焊接试验,并利用光学显微镜、扫描电镜、万能试验机、冲击试验机、显微硬度仪等对焊接接头的显微组织结构及力学性能进行研究。结果表明:焊缝金属为奥氏体和铁素体组织,在Q345侧热影响区(HAZ)发现有明显的碳元素迁移现象,焊缝中Cr、Ni等合金元素成分迁移很小,稀释不明显;焊缝-316L交界处形成了宽约50μm的熔合区。ER309L焊接接头在强度、塑性、冲击韧性和显微硬度方面优于ER308焊接接头;同时,两者拉伸断裂均发生在Q345侧HAZ部位,接头焊缝冲击韧性良好,显微硬度高于两侧母材。

Q345 /316 L dissimilar steel welding joints were produced by gas tungsten arc welding using two welding wires of ER309 L and ER308,respectively. Microstructure and mechanical properties of the welding joints were investigated by means of optical microscope,SEM and EDS analysis,tensile test,impact and hardness tests. The results show that the microstructure of the welding is composed of austenite and ferrite. The diffusion of carbon element is obvious in the heat effected zone（ HAZ） of the Q345 steel side,and no significant diffusion of Cr and Ni elements is observed in the welding seam,and no obvious dilution of the element is found. A complex fusion zone with about 50 μm width is formed at the welding-316 L steel interface. Compared to ER308 welded joints,the ER309 L welded joints exhibit better performance of tensile strength,plasticity,impact toughness and hardness. All the tensile fracture occurs at the HAZ of the Q345 steel side,the impact toughness and the hardness of the welded joints are higher than that of the base materials.