Microstructure characteristics and fatigue properties of welded HSLA with and without buffer layer

► Fatigue behavior of welded HSLA with and without buffer layer was studied. ► Effect of microstructure on fatigue behavior and hardness of welded HSLA was studied. ► The transition of fatigue propagation mechanisms in HSLA steel was also studied. ► Moderate thick buffer layer can greatly improve the fatigue behavior and hardness. ► The thick influence of buffer layer was critical to fatigue behavior and hardness.