Nuclear grade austenitic stainless steel 321 contains titanium for severe corrosive conditions and is used for process equipment, aircraft exhaust manifolds and boiler shells. Taguchi-based grey relational analysis technique has been considered to optimize the input parameters for welding SS321 material using activated tungsten inert gas welding process. The optimized input parameters were identified from the multiple output responses, i.e. arc length of 3 mm, welding current of 220 Amps and welding speed of 120 mm/min (A₁B₃C₁). The analysis of the variance table was performed to calculate the importance of the input parameters in the weldment quality. Also, the influence of the heat input on the depth of penetration and bead width at different arc lengths has been studied. The mechanical integrity is evaluated in terms of tensile strength for base metal (BM) (621 MPa) and weld metal (WM) (624 MPa) specimens by conducting the uniaxial tensile test. The 180° bend test with WM sample revealed the ductility level and was free from fissures and cracks. Charpy impact test results depicted the toughness values of BM (123.17 J) and WM (113.46 J) samples. Microstructural investigations at the SS321 WM highlighted the existence of columnar and equiaxed dendrites in the fusion zone. Moreover, the formation of titanium carbide reduces the chances of weld decay. Ferrite number measurement shows that the amount of delta ferrite is higher in WM (5.9) than in BM (1.2). The existence of dimples and voids in the fractographic analysis of the failed specimens (tensile and impact) confirms the ductile type of failure.

核级奥氏体不锈钢321含有用于严重腐蚀条件的钛，可用于工艺设备，飞机排气歧管和锅炉壳体。已经考虑使用基于Taguchi的灰色关联分析技术来优化使用活性钨极惰性气体保护焊工艺焊接SS321材料的输入参数。从多个输出响应中识别出优化的输入参数，即电弧长度为3 mm，焊接电流为220 Amps，焊接速度为120 mm / min（A ₁ B ₃ C ₁）。进行方差表分析以计算输入参数在焊件质量中的重要性。此外，还研究了热量输入对不同电弧长度下的熔深和磁珠宽度的影响。通过进行单轴拉伸试验，根据母材（BM）（621 MPa）和焊接金属（WM）（624 MPa）试样的拉伸强度评估机械完整性。使用WM样品进行的180°弯曲测试显示出延展性水平，并且没有裂缝和裂纹。夏比冲击试验结果描述了BM（123.17 J）和WM（113.46 J）样品的韧性值。SS321 WM的微观结构研究突显了融合区中存在柱状和等轴枝晶。此外，碳化钛的形成减少了焊接衰减的机会。铁素体数的测量表明，WM（5.9）中的铁素体δ量高于BM（1.2）。断裂样品的形貌分析中的凹痕和空隙（拉伸和冲击）的存在证实了韧性的破坏类型。