Hydrogen atoms on the SCC behavior of SUS301L-MT stainless steel laser-arc hybrid welded joints

Laser-arc hybrid welding (LAHW) process has been applied for excellent manufacturing the new generation subway vehicles underframe using cold rolled SUS301 L stainless steel. However, the effects of hydrogen atoms on the stress corrosion cracking (SCC) behavior are still unclear, which is probably a latent risk for the application. Here, in combination with the microstructures and fracture morphologies analysis, the effects of hydrogen atoms on SCC behavior of SUS301L-MT (MT = 15% cold rolling, middle tensile) stainless steel LAHW welded joints and the base metal (BM) was investigated by slow strain rate tensile (SSRT) method during applied cathode potentials on the specimen in 3.5 wt.% NaCl solution. The results indicated that the SUS301L-MT ASS LAHW welded joints exhibited lower SCC susceptibility than that of BM, particularly at very negative cathode potential, −1200 mV and −1400 mV, the SCC susceptibility of the welded joints (～0.3) is 2 times lower than that of BM (～0.6), due to the high solubility of hydrogen atoms and low hydrogen embrittlement (HE) susceptibility of weld metal (WM). We hope this study can help to assist LAHW process widely apply for the manufacturing of new generation subway vehicles underframe as well as other welding structures.