The influence of joint gap on the strength of hybrid Nd:yttrium-aluminum-garnet laser-metal inert gas welds

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.