Fatigue Strength Enhancement of Butt Welds by Means of Shot Peening and Clean Blasting

Abstract

Shot peening is a mechanical surface treatment to improve the fatigue strength of metallic components. Similarities exist between regular shot peening and conventional industrial clean blasting. However, the main difference between these two processes is the peening media used and the lack of control and documentation of peening parameters. The clean blasting process is not yet qualified to optimize fatigue enhancement, although it holds a similar potential to regular shot peening. Clean blasting is frequently applied to welded components, with the purpose of surface preparation for application of corrosion protection. This article presents the results of regular shot peened double V-groove (DV) butt welds made from construction steels S355N and S960QL, as well as the high strength aluminum alloy Al-6082. The peening parameters are varied widely. Furthermore, the effect of coverage and intensity is investigated to test the robustness of the peening processes. The data is completed with industrially clean blasted welds, representing typical workshop conditions. The overall objective of this work is to derive minimum peening parameters that still allow significant fatigue strength benefits. The presented data show a high robustness of the fatigue results to peening parameters.

Keywords

• welded joints
• fatigue strength
• steel
• aluminum
• post-weld treatment
• shot peening
• clean blasting
• residual stresses