Evaluation of blast cleaning effects on the fatigue strength considering different weld details in structural steel

Blast cleaning is a process commonly used to remove slag residues, welding spatter, and similar contaminants from welded components in order to prepare surfaces for coating. Recent studies have also demonstrated the potential of blast cleaning to enhance fatigue strength, primarily due to surface hardening and the introduction of compressive residual stresses. However, unlike the related process of shot peening, which is recognized as a post-weld treatment method, the fatigue strength enhancement achieved through blast cleaning has not yet been verified in its entirety. There is still a need for research, particularly regarding the influence of varying notch sharpness in different weld details and the stability of the induced compressive residual stresses. In this context, fatigue strength investigations were conducted on welded butt joints, transverse stiffeners, and longitudinal stiffeners in the blast cleaned condition under constant amplitude loading using S355J2+N construction steel. Prior to fatigue testing, the welded specimens were analysed regarding surface residual stress distribution as well as the impact of different tension and compression preloads. The results show that the initial residual stress state changes depending on the level and number of cyclic preloads. With regard to the improvement in fatigue strength due to blast cleaning, it is shown that the degree of enhancement decreases as the notch sharpness increases.