Sulfide stress corrosion cracking and weldability of domestic X70 pipeline steels

Constant load test and implant test were utilized to study the sulfide stress corrosion cracking (SSCC) in the sulfide solution and weldability of domestic X70 pipeline steels. Electronic microscopic testing was used to analysis the fracture morphology in implant tests. The results suggested that it is element Mn, P, not element C that lead to domestic X70 pipeline steels with different chemical compositions have different resistance to SSCC. The σ_cr (critieal stress) of the joint produced by LINCOLN E6010 welding rod is 630 MPa, 610 MPa with preheating(70℃) or without preheating respectively. The appearance of implant fracture is charaterized by civility, permit cleavage and cleavage.