Precipitation strengthened Ni based alloy, Incoloy 925 is widely used in the H₂S-containing hot sour environments because of its excellent properties. Metallurgical properties, which is known to affect the performace of this alloy greatly depends on the welding technique adopted, ageing condition, formation of inter-metallic phases and hardness. Hence, in this research work, the joints of Incoloy 925 are accomplished in a single pass with the use of nano-SiO₂ activtated flux tungsten inert gas (A-TIG) welding process. Further, the A-TIG welded joints were subjected to direct ageing for 4 h and 8 h at 732 °C and air-cooled. Recrystallized grains were observed in the fusion region in the as-welded (AW) condition. The grain boundaries of the weld seams were precipitated with M₇C₃ carbides, discrete amounts of η (Eta) and σ (Sigma) phases after subjecting to DA. The tensile strength of the weld seams was increased to ∼ 41 % and 31 % after having exposed to DA for 4 and 8 h respectively. The failures due to tension occurred in the fusion zone of Incoloy 925 irrespective of the DA conditions. The formation of η phase and high angle grain boundaries (HAGBs) resulted in a lower percentage of elongation and impact toughness when aged for 8 h.

沉淀强化的镍基合金，Incoloy 925因其优异的性能而广泛用于含H ₂ S的酸性环境中。已知会影响该合金性能的冶金性能在很大程度上取决于采用的焊接技术，时效条件，金属间相的形成和硬度。因此，在这项研究工作中，使用纳米SiO ₂活化焊剂钨极惰性气体（A-TIG）焊接工艺，一次完成了Incoloy 925的接头。此外，将A-TIG焊接接头在732°C的温度下直接老化4小时和8小时，然后进行风冷。在焊接（AW）条件下，在熔合区观察到重结晶晶粒。用M沉淀焊缝的晶界。₇ C ₃碳化物，经历DA后离散数量的η（Eta）和σ（Sigma）相。在DA分别暴露4小时和8小时后，焊缝的抗拉强度提高到约41％和31％。不论DA条件如何，Incoloy 925的熔化区都会发生由于张力引起的失效。η相和高角度晶界（HAGBs）的形成导致时效8 h时伸长率和冲击韧性的百分比降低。