Modeling of Failure Modes of Gas Metal Arc Welds in Notched Lap-Shear Specimens of HSLA Steel

The failure modes of gas metal arc welds in notched lap-shear specimens of high strength low alloy (HSLA) steel are investigated. Notched lap-shear specimens of gas metal arc welds were first made. Quasi-static test results of the notched lap-shear specimens showed two failure locations for the welds. The specimens cut from coupons with shorter weld lengths failed near the weld root whereas the specimens cut from coupons with longer weld lengths failed near the weld toe. Micro-hardness tests were conducted in order to provide an assessment of the mechanical properties of the base metal, the heat affected zone, and the weld metal. In order to understand the failure modes of these welds, finite element models were developed with the geometric characteristics of the weld metals and heat affected zones designed to match those of the micrographs of the cross sections for the long and short welds. Three-dimensional finite element analyses were conducted with consideration of micro void nucleation and growth. The distributions of the void volume fraction and the necking modes near the welds shown from the finite element analyses correlate well with the failure modes observed in the experiments.