304不锈钢水下湿法焊接工艺

Underwater wet welding process of 304 stainless steel

利用自保护镍带药芯焊丝,对304不锈钢进行水下湿法焊接试验,并分析了焊接接头的微观组织和力学性能.结果表明,304不锈钢水下湿法焊接过程稳定,飞溅少,成形良好,增加焊接电流会显著增加熔宽,而熔深变化很小,增加焊接电压,熔宽增加,焊缝成形变差且飞溅增多.焊缝金属由单一的镍基γ-固溶体相组成,焊接接头热影响区存在晶粒粗化现象.拉伸试验试件均断裂在焊缝处,焊接接头平均抗拉强度值达到450 MPa,呈现为脆性断裂,热影响区硬度因晶粒粗化有所降低.

Underwater wet welding of 304 stainless steel is carried out with nickel-based self-shielded flux-cored wire,and the microstructure and mechanical properties of welded joints are analyzed. The experimental results show that the welding process is relatively stable and the weld appearance is good with few spatters. The bead width notably increases as the welding current rises,while the bead penetration increases a little. Higher welding voltage leads to larger bead width and poor bead appearance with lots of spatters. The microstructure in the weld is mainly composed of Ni-based γ-solid solution. Grains in heat-affected zone coarsen. The results indicate that the fracture location during tensile test is in the weld with brittle fracture mode,and the average tensile strength is up to 450 MPa. The hardness in HAZ is a little lower than that in parent metal due to coarsened grains.