保护气对304N不锈钢K-TIG焊接头组织性能的影响

Influence of shielding gas on microstructure and properties of K-TIG welded 304N stainless steel

摘要: 使用小孔钨极氩弧焊(K-TIG, keyhole TIG)焊接设备对13.5 mm厚度304N 不锈钢板材进行了焊接，不开坡口一道焊透成型。利用SEM，XRD，共聚焦显微镜，铁素体仪，显微硬度计分析了不同保护气体组成对焊缝化学成分、焊接接头各区域微观组织以及性能的影响。结果表明，相对于母材，当采用纯Ar作为保护气体时，焊缝N含量下降了18%，铁素体含量增加了20倍，焊缝中心的显微硬度下降了15%;当采用Ar + 3%N2作为保护气体时，焊缝N含量增加了90%，铁素体含量下降了84%，甚至某些区域的铁素体含量为零，焊缝的显微硬度提高了14%以上。

Abstract: 304N stainless steel plate with 13.5 mm in thickness was butt welded by K-TIG without groove. The chemical components，microstructures and properties of butt welded joint were studied by SEM, XRD, 3D measuring laser microscope, hardness tester. The experimental results indicate that the N-content in the weld metal reduces by 18%, the ferrite content of weld metal increases by 20 times, and the hardness of weld decreases by 15%, compared with that of base material when pure Ar gas is used as the shielding gas. The N-content in weld metal increases by 90%, the ferrite content of weld metal reduces by 84%, and the hardness of weld increases by 14% at least when the shielding gas is the mixture of Ar + 3%N2.