14th International Conference on Shot Peening

Fatigue strength improvement of welded joints by means of shot peening and clean blasting

Th Nitschke-Pagel, Klaus Dilger, J.Hensel, H.Eslami

Institut für Füge- und Schweißtechnik, Technische Universität Braunschweig

Langer Kamp 8, D-38106 Braunschweig, Germany

Abstract

Shot peening is a well established and state of the art mechanical surface treatment to improve the fatigue strength of metallic components. Clean blasting is a familiar process to regular shot peening and used in frequent applications of welding practice. However, the main difference between these two is the peening media used and the lack of control and documentation of peening parameters. The clean blasting process is yet not qualified to optimize fatigue enhancement although it holds similar potential as 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 results of regular shot peened DV-butt welds made from construction steels S355N and S960QL as well as high strength aluminum alloy Al-6082. The peening parameters are varied widely. Further, 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 shows a high robustness of the fatigue results to peening parameters. This indicates high potential of shot peening and clean blasting for fatigue strength enhancement. The clean blasting parameters shall be controlled in terms of coverage and intensity to still allow benefits as commonly known from shot peening.