Effect of buffer layer and notch location on fatigue behavior in welded high-strength low-alloy

A soft buffer layer (BL) between the weld metal (WM) and the parent metal (PM) was introduced in this study. To study the effect of a BL on mechanical properties, two types of joints made from welded high-strength low-alloy (HSLA) specimens with or without a BL were prepared. To investigate the influence of the notch location, the welded HSLA specimens machined with a U-notch in the WM or the PM. These conditions were examined to determine the effects of the BL and the notch location on the fatigue characterizations and the microscopic features of the fatigue-fractured surface. Extended-compact tension (E-CT) specimens were used for all tests. Paris fatigue curves and hardness distributions of the welded HSLA specimens with or without a BL were measured, and relevant scanning electron microscope (SEM) images were taken. The results showed that the presence of a BL significantly improved the fatigue crack growth behavior when a U-notch was in the WM. The notch location greatly influenced the fatigue behavior and the surface features of the fatigue-fractured specimens.