Corrosion fatigue behavior of X65 pipeline steel welded joints prepared by CMT/GMAW backing process

• Published in: Corrosion science Vol. 225; p. 111568
• Main Authors: Yan, Yusheng, Zhong, Shifang, Chen, Zhe, Sun, Youhui, Xu, Lianyong, Zhao, Lei, Han, Yongdian
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2023
• Subjects: Cold metal transfer (CMT); H2S corrosion-fatigue behavior; Microstructure; Welded joints; X65 pipeline steel; Welded joints; X65 pipeline steel; Microstructure; Cold metal transfer (CMT); H2S corrosion-fatigue behavior
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2023.111568

The corrosion-fatigue behavior of X65 welded joints, processed by cold metal transfer (CMT) and gas metal arc welding (GMAW) backing, was examined. The application of the CMT backing process led to a 22% increase in the corrosion-fatigue performance, which was attributed to the optimization of the microstructure (synergistic cracking-arrest ability of acicular ferrite (AF) and grain boundary ferrite (GBF)) and the reduction in the stress concentration at the weld root. Nonetheless, a lower heat input contributed to a consequent decrease in corrosion-fatigue performance. In addition, H2S corrosion fatigue was governed by the combined effect of anodic dissolution and hydrogen embrittlement. •The corrosion-fatigue behavior of the cold metal transfer (CMT) and gas metal arc welding (GMAW) backing were compared.•The CMT backing process improves the corrosion fatigue performance by about 22% compared to the GMAW backing process.•CMT backing process improves corrosion fatigue performance by optimizing microstructure and reducing stress concentration.•The H2S corrosion-fatigue failure is governed by the combined effect of anodic dissolution and hydrogen embrittlement.