超级双相不锈钢2707搅拌摩擦焊焊接接头的组织与性能

Microstructure and mechanical properties of friction stir welded joint of super duplex stainless steel 2707

采用氮氧分析仪、光学显微镜、扫描电镜（SEM）、X射线衍射仪（XRD）、拉伸试验机和显微硬度计对超级双相不锈钢2707搅拌摩擦焊焊接接头的氮元素含量、微观组织和力学性能进行了研究。结果表明：焊缝的氮元素含量与母材的氮含量相同,焊缝区铁素体相和奥氏体相均为细小的等轴晶,铁素体含量与母材接近且无第二相析出。搅拌摩擦焊通过动态再结晶细化了焊缝区的晶粒,使得焊接接头的强度和硬度均高于母材,焊接接头的伸长率略低于母材,微观断口仍显示为韧性断裂。

Nitrogen content, microstructure, mechanical properties of friction stir welded joint of super duplex stainless steel 2707 were investigated by means of nitrogen and oxygen analyzer, optical microscope, scanning electron microscopy（SEM）, X-ray diffractometer, tensile test machine and Vickers hardness tester. The results show that the nitrogen content of the welded seam is the same as that of the base mental（BM）. The ferrite and austenite phases in the weld zone are both fine equiaxed crystals, and the ferrite content is close to the base metal and there is no precipitation of the second phase. Through dynamic recrystallization, friction stir welding refines the grain in the weld zone, making the strength and hardness of the welded joint higher than the base metal, the elongation of the welded joint is slightly lower than that of the base metal, and the micro-fracture still shows ductile fracture.