保护气配比对高氮钢焊丝接头组织性能的影响

Effects of shielding gas ratio on microstructure and properties of high nitrogen steel welded joint

对高氮奥氏体不锈钢焊缝进行固氮,在多元活性保护气氛条件下,用氮的质量分数为0.46%的高氮钢焊丝进行焊接试验,研究保护气体不同氮气配比对焊丝接头的固氮效果、气孔敏感性、显微组织及力学性能影响。结果表明:随保护气体中氮气配比增加,焊丝接头的氮含量先增大后趋于稳定,气孔倾向先减后增;焊缝组织中奥氏体枝晶变粗,枝晶间距增大;当氮气配比为15%时,接头的抗拉强度和断后伸长率最大,分别为905 MPa和21.2%,冲击韧性受氮含量及气孔的共同影响先增后减。

In order to fix nitrogen in the welding seam of high nitrogen steel,high nitrogen welding wire with a nitrogen content of0.46%was used for the high nitrogen steel welding process test under the condition of multiple active protective atmosphere.The effects of different nitrogen ratios in the shielding gas on the nitrogen fixation effect,pore sensitivity,microstructure and mechanical properties of high nitrogen steel welded joints were studied.The results show that with the increase of the nitrogen ratio in the shielding gas,the nitrogen content of the welded joint first increases and then tends to be stable,and the pore tendency first decreases and then increases.The austenite dendrites in the weld structure become thicker and the dendrite spacing increases.When the nitrogen ratio is 15%,the tensile strength and elongation after fracture of the welded joint reach the maximum,which are 905 MPa and 21.2%,respectively.The impact toughness first increases and then decreases due to the combined effects of nitrogen content and porosity trend.