Product Code: JLA_18_3_181

Authors:
M. Wouters
Division of Manufacturing Systems Engineering, Luleå University of Technology, S-971 87 Luleå, Sweden

J. Powell
Division of Manufacturing Systems Engineering, Luleå University of Technology, S-971 87 Luleå, Sweden and Laser Expertise Ltd., Acorn Park Ind. Estate, Harrimans Lane, Nottingham NG7 2TR, United Kingdom

A. F. H. Kaplan
Division of Manufacturing Systems Engineering, Luleå University of Technology, S-971 87 Luleå, Sweden

This article presents the results of an experimental and theoretical analysis of the effect of joint gap on the strength of hybrid laser-metal inert gas welds. The welds were of the partial 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. 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 discussion on joint gap optimization.