高氮奥氏体不锈钢与603马氏体高强钢焊接接头组织及性能

高氮奥氏体不锈钢与603马氏体高强钢因优越的力学性能在装甲防护领域具有广阔的应用前景。根据“低强匹配”原则，采用ER307Mo奥氏体不锈钢焊丝对30 mm厚的高氮奥氏体不锈钢和603马氏体高强钢脉冲熔化极惰性气体保护焊对接焊接，并分析焊接接头微观组织及力学性能。研究结果表明：试验得到了表面成形良好、内部无裂纹、未熔合等缺陷的焊接接头；焊缝组织主要为奥氏体以及被奥氏体基体包围的铁素体树枝晶，高氮奥氏体不锈钢熔合线附近组织主要为奥氏体，603钢熔合线附近组织主要为条片状马氏体、贝氏体以及回火马氏体；接头的断裂形式以韧性断裂为主，存在少量的解理断裂特征，能谱仪点扫描结果表明，韧窝中心的第2相粒子为富Fe的碳化物；焊接接头的平均抗拉强度达722 MPa，平均断后延伸率达20.2%；焊缝金属的动态屈服强度为913 MPa，最大工程应力为2 045 MPa，抗冲击性能优于603钢母材。

Microstructures and Mechanical Properties of Welded Joints Made of 603 High Strength Steel and High Nitrogen AusteniticStainless Steel

Due to superior mechanical properties, high nitrogen austenitic stainless steel and 603 martensitic high strength steel are ideal materials for armor protection. According to the principle of “low strength matching”, ER307Mo austenitic stainless steel wire is selected for welding 30mm thick high nitrogen austenitic stainless steel and 603 martensitic high strength steel by pulse MIG butt welding. The microstructures and mechanical properties of the welded joints are analyzed. The results show that the welded joints with good surface appearance and no internal cracks and fusion defects are obtained. The microstructure is primarily austenite and ferrite dendrite surrounded by austenite matrix. The microstructure near the fusion line of high nitrogen austenite stainless steel is mainly austenite, and the microstructure near the fusion line of 603 steel is mainly strip martensite, bainite and tempered martensite. The joint's fracture is mainly ductile fracture, with a small percentage of cleavage fracture. EDS point scanning results show that the second phase particles at the center of the dimple are Fe rich carbides. The average tensile strength of the welded joints is 722 MPa and the average elongation after fracture is 20.2%. The dynamic yield strength of the welding metal is 913 MPa, the maximum engineering stress is 2 045 MPa, and the impact resistance exceeds that of the 603 steel base metal.