高氮奥氏体焊丝焊接超高强钢接头组织和性能

为解决超高强钢焊接冷裂纹问题，采用强度低于母材的高氮奥氏体丝材进行GMAW工艺试验，研究在不同坡口角度下超高强钢焊接接头组织性能. 结果表明，采用该焊丝获得的接头焊缝成形良好，焊缝截面未见裂纹缺陷. 熔合线附近组织主要为针状和板条状马氏体，焊缝组织主要为奥氏体及被奥氏体基体所包围的铁素体树枝晶. 熔合线附近马氏体区硬度平均值为530 HV；焊缝区硬度平均值为275 HV. 相对于60°坡口接头，90°坡口接头熔合线附近马氏体组织硬度更高. 90°坡口接头的抗拉强度平均达到850 MPa，最高达887 MPa，而60°坡口接头抗拉强度平均仅为690 MPa.

Microstructure and properties of ultra-high strength steel joints welded with high nitrogen austenite wire

In order to solve the problem of cold cracks in ultra-high-strength steel welding, the GMAW process experiment was carried out with high-nitrogen austenitic wire with lower strength than the base metal to study the microstructure and properties of ultra-high-strength steel welded joints at different grooved angles. The results show that welded joints are well formed without cracks according to cross-section of weld, the microstructure near the fusion line is mainly acicular and lath martensite, and the weld structure is mainly austenite and ferrite dendrites surrounded by austenite matrix; the average hardness of the martensite zone near the fusion line is 530 HV; the average hardness of the weld zone is 275 HV; compared to 60° grooved joints, the hardness of the martensite structure near the fusion line of 90° grooved joints are higher; The average tensile strength reaches 850 MPa, and the highest is 887 MPa, while the average tensile strength of 60° groove joints is only 690 MPa.