Inhomogeneous constructive modelling of laser welded bead based on nanoindentation test

Abstract

For a typical tailor welded blank (TWB), the mechanical performances of the weld metal vary dramatically with different distances to the longitudinal centreline of the weld. Constructive models that can describe this laterally inhomogeneous behaviour of welds, however, have rarely been reported. In this work, the elastoplastic properties (i.e. hardness, Young’s modulus, initial yield stress, strength coefficient and strain hardening exponent) of a laser welded bead, made of DX56D and DP600 automotive steel sheets of different gauges, were determined according to the nanoindentation response. Based on the measured data, a constructive model of the weld bead, which has taken into account the performance inhomogeneity traversing the weld line, was built. This constructive model was justified by the fact that the numerical results of Erichsen cupping tests for TWB specimens are in good agreement with the corresponding experimental ones.