Welding heat input for synergistic improvement in toughness and stress corrosion resistance of X65 pipeline steel with pre-strain

• Published in: Corrosion science Vol. 206; p. 110478
• Main Authors: Han, Yongdian, Zhong, Shifang, Tian, Lei, Fei, Jiyuan, Sun, Youhui, Zhao, Lei, Xu, Lianyong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2022
• Subjects: Coarse-grained heat-affected zone; Effects of pre-strain; Hydrogen embrittlement; Microstructure; Stress corrosion; X65 pipeline steel; Stress corrosion; Coarse-grained heat-affected zone; X65 pipeline steel; Microstructure; Effects of pre-strain; Hydrogen embrittlement
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2022.110478

The microstructure, hydrogen embrittlement sensitivity, fracture toughness, and influence of pre-strain on the sulfide stress corrosion cracking (SSCC) sensitivity of the coarse-grained heat-affected zone of X65 pipeline steel with large deformation were studied to determine the optimal welding heat input in an acidic H2S environment. After pre-straining, the microstructures of the specimens changed insignificantly, but their ductility decreased. The acicular ferrite microstructure obtained under a low heat input demonstrated the synergistic improvement in the SSCC resistance and fracture toughness under pre-strain, especially at t8/5 = 20 s. The M/A constituents interface potentially causes microcrack initiation and interconnection under pre-strain. •The microstructures of CGHAZ with different welding heat input are observed.•When t8/5 = 20, 25, 30, and 60 s, the CGHAZ has excellent fracture toughness and HE sensitivity.•The morphology and distribution of the microstructure do not change significantly after 5% pre-straining.•The CGHAZ with a t8/5 of 20 s can synergistically improve SSCC resistance and fracture toughness with pre-strain.