High-strength pipeline steels are widely employed for long-distance energy transportation due to their superior strength, toughness, and weldability. However, maintaining the structural integrity of girth welds under complex mechanical loading and harsh environmental conditions remains a major concern. This review synthesizes current understanding of mechanical degradation mechanisms in high-strength pipeline girth welds, with emphasis on the interplay among metallurgy, welding processes, and service performance. Particular focus is placed on two key mechanisms, including weld strength mismatching and heat-affected zone (HAZ) softening, which govern strain localization and premature failure. The role of geometric factors (e.g., pipe diameter, wall thickness, and weld misalignment) and service conditions in influencing degradation are also critically assessed. The analysis highlights that conventional welding practices and existing standards do not adequately account for actual strength mismatch, HAZ softening, or their combined effects on strain distribution. Consequently, current qualification approaches may be insufficient to ensure long-term reliability. Key limitations in existing studies are identified, and future directions are proposed, including the need for improved strain-based design methodologies, advanced multiscale modeling, and localized property evaluation to optimize welding performance.
Zhang et al. (Wed,) studied this question.