Effects of laser shock processing on H₂S stress corrosion fractures of X70 pipeline steel welded joints

The surfaces of X70 pipeline steel welded joints were processed with laser shock and its stress corrosion sensitivity was investigated in NACE saturated H₂S solutions by slow strain rate testing (SSRT). The fracture surfaces were analyzed with scanning electric microscope (SEM). The results show that the X70 pipeline steel welded joints in primitive state is brittle fracture. The cracks of tensile fracture is stress corrosion cracking. The mechanical properties of the X70 pipeline steel welded joints after laser shock processing is enhanced, its dimple dimension and depth becomes smaller, and the fracture mode is ductile fracture. SCC is the main mechanism of X70 pipeline steel welded joint stress corrosion cracking. Laser shock processing reduces the tendency of SCC and improves stress corrosion resistance H₂S of the welded joint.