Effect of welding conditions on stress–strain curves at welds through ball indentation techniques

Abstract

A mechanical properties estimation with instrumented indentation techniques (IIT) using spherical indenter is applied to steel welds with mechanical heterogeneity. The melt–run welded–plate specimens were prepared using TIG welding under various heat input conditions. The distribution of hardness at the welds was measured by Vickers hardness test. Then, the effect of welding conditions on hardness of hardened weld metal was arranged by the parameter of cooling rate. Based on the hardness change due to hardening induced by welding, the stress–strain curve obtained for base metal was corrected to estimate those for weld metal. Meanwhile, the stress–strain curves at welds were estimated through the IIT. The estimated stress–strain curves were compared with those corrected from hardness change to discuss availability of mechanical properties estimation with the IIT. In addition, the effect of welding conditions on the work–hardening coefficient and exponent in the estimated stress–strain curve (n–power law constitutive model) was discussed. Thus, it is expected that the IIT using spherical indenter becomes useful to estimate the stress–strain curve more precisely at steel welds with mechanical heterogeneity.