Stress corrosion cracking analysis of gas tungsten arc welded 304 stainless steel joints in marine environment

The gas tungsten arc welded 304 stainless steel joints were prepared using two distinct welding parameters (current and welding speed), then the evolution of the microstructure, the mechanisms of stress corrosion cracking, and the electrochemical corrosion behavior of the welded joints were studied. The results indicate that the microstructure of the welded joints is mainly dendrite, and the main phase’s average grain size of base metal (16.36 µm) is much higher than that of the welded joints (6.61 µm and 7.14 µm). Welded joints characterized by higher welding current and speed exhibit reduced stress corrosion cracking sensitivity. Notably, joints under higher welding current and speed significantly enhances corrosion resistance, as evidenced by a lower passive current density (Ipass = 4.54 × 10^-7 A/cm^2), wide passive range (ΔE = 217 mV). Furthermore, the accumulation of chloride ions at stress concentration sites of welded joints contributes to pitting corrosion. This stress concentration at the pitting sites exacerbates anodic dissolution and hydrogen accumulation, ultimately leading to failure.