低镍不锈钢激光-电弧复合焊接头组织性能研究

Effect of welding heatinput on microstructure and properties of MAG welded joint for Low nickel high nitrogen austenitic stainless steel

摘要:

低镍含氮奥氏体不锈钢强度高,韧性佳,在化工装备及建筑装饰等领域广泛应用。为揭示保护气体对低镍含氮奥氏体不锈钢焊接接头微观组织和力学性能的影响机制,分别采用92%Ar+8%N2与95%Ar+5%CO2两种混合比例的保护气体对08Cr19Mn6Ni3Cu2N低镍含氮奥氏体不锈钢进行了激光-MAG电弧复合焊。研究表明：氮气的加入使焊接接头平均显微硬度有所下降；电弧收缩明显,焊接飞溅增加且体积增大,电弧稳定性变差；焊缝中奥氏体含量增加约20%,而铁素体枝晶变细,二次枝晶臂变短。焊缝组织中未发现σ相及氮化物析出；从四个晶面观察奥氏体晶粒尺寸也是由于氮气的加入而减小；焊接接头拉伸性能略微下降,但耐腐蚀性能提高。

Abstract:

The laser-MAG hybrid welding of 08Cr19Mn6Ni3Cu2N with low nickel and nitrogen content was carried out using 92% Ar+8% N2and 95% Ar+5% CO2 as shielding gas. The mechanism of the effect of shielding gas on the microstructure and properties of the welded joint was investigated. The results show that the average microhardness of the weld decreases with the addition of nitrogen, the welding spatter increases with the increase of arc volume and the decrease of arc stability, and the ferrite content in the weld decreases from 14.1% to 10.9% , the ferrite Dendrite also became finer and the secondary dendrite arm became shorter. There are only a few phases and two phases in the weld, and no phases and nitrides are found. The size of austenite grain decreases with the addition of nitrogen from four crystal planes.