DETERMINING THE CONSTITUTIVE PROPERTIES OF THE HEAT-AFFECTED ZONE IN A RESISTANCE SPOT WELD

A methodology is described for determining the mechanical properties o f the heat-affected zone (HAZ) in a resistance spot weld. To perform d etailed finite-element analyses of spot weld overload failures, it is necessary to have the mechanical properties of the various HAZ subzone s. To this end, simulated HAZ material samples were fabricated in a pr ocess that utilized a resistance spot welding machine fitted with spec ially modified electrodes. Tensile tests at several loading rates were performed on miniature notched-bar specimens machined from the simula ted HAZ material. These tests provided the empirical data from which t he strain hardening capacities and strain rare sensitivities of the we ld HAZ were determined through detailed finite-element analyses of the notched-bar tensile tests.