Product Code: PIC06_504

The Influence of Joint Gap on the Strength of Hybrid Nd:YAG Laser-MIG Welds
Authors:
Marc Wouters, Luleå University of Technology; Luleå Sweden
John Powell, Laser Expertise Ltd.; Nottingham Great Britain
Alexander Kaplan, Lulea University of Technology; Lulea Sweden
Presented at PICALO 2006

This paper presents the results of an experimental and theoretical analysis of the effect of joint gap on the strength of hybrid laser-MIG welds. The welds were of the non-full penetration butt type with various joint gaps but identical weld penetration. Impact testing established that a zero gap gave a weak weld because the weld geometry contained the equivalent of a sharp crack where the unwelded parts met each other and the root of the weld. A small gap between the workpieces improved the weld impact strength as the sharp crack effect became dissipated. Further increases in gap width resulted in a weakening of the joint and this is the subject of a theoretical discussion on joint gap optimisation.