T92/Super304H异种钢焊接接头的组织结构和力学性能

Microstructures and mechanical properties of T92/Super304H dissimilar steel weld joints

采用钨极氩弧焊(GTAW)技术,采用ERNiCr-3和ERNiCrMo-3两种镍基焊丝实施T92/Super304H异种钢焊接,并对接头的显微组织结构及力学性能进行测试分析。结果表明:T92侧热影响区(HAZ)中粗晶区析出大量的第二相颗粒,细晶区则为细小的索氏体组织;Super304H侧HAZ奥氏体晶粒长大,晶界析出明显;ERNiCr-3焊接的焊缝组织呈胞状结构,晶粒粗大;ERNiCrMo-3焊接的焊缝组织呈柱状晶组织特征。ERNiCrMo-3焊接的接头强度、塑性及硬度较大,拉伸断裂位于Super304H母材;而ERNiCr-3焊接的接头强度、硬度较低,但冲击韧性较高,拉伸断裂位于焊缝。

T92/Super304H dissimilar steel joints were produced through gas tungsten arc welding （GTAW） technique, using two Ni-based welding wires of ERNiCr-3 and ERNiCrMo-3, respectively. The microstructures and mechanical properties of the joints were then studied. The results show that in the heat-affected zone （HAZ） of the T92 side, lots of second-phase particles precipitate along the grain boundaries and inside the grains of the prior austenites. The fine grain zone of the T92 side HAZ is ofa sorbite structure. In the Super304H side HAZ, the austenitic grains grow up rapidly with lots of precipitates along the grain boundaries. The ERNiCr-3 welding seam in the joint is of a coarse cellular structure. Comparatively, the ERNiCrMo-3 welding seam is of dense columnar grains. The ERNiCrMo-3 welded joints have higher strength, ductility and hardness, however, the ERNiCr-3 welded joints have a higher impact toughness value. Moreover, the tensile fracture of the formers takes place in the Super304H base metal, while that of the latters happens in the welding seam.