Evaluation of Charpy impact toughness using side-grooved specimen for hybrid laser-arc welds of ultra-high-strength steel

Abstract

This paper discusses the significance of a narrow hard weld bead, produced by hybrid laser-arc welding, on the Charpy absorbed energy. A parametric finite element analysis with various strength mismatching and bead widths has been conducted on the strain field of side-grooved and normal Charpy specimens. The narrow weld bead promotes the accumulation of plastic strain energy on the base metal side. This feature is more significant in the normal specimen than in the side-grooved specimen. The results show that the method based on the Weibull stress criterion for converting the absorbed energy of the side-grooved specimen to that of the normal specimen can be applied to hybrid laser-arc welds of ultra-high-strength steel. The converted energy is consistent with the absorbed energy measured in the normal specimen. This study indicated that the absorbed energy of side-grooved specimen corresponding to the absorbed energy of the normal V-notch specimen increases with increasing hard zone width. On the other hand, the influence of strength mismatch ratio on the difference of the absorbed energy is rather weak.