Analysis of the Charpy V-notch test for welds

The ductile-brittle transition for a weld is investigated by numerical anal yses of Charpy impact specimens. The material response is characterized by an elastic-viscoplastic constitutive relation for a porous plastic solid, w ith adiabatic heating due to plastic dissipation and the resulting thermal softening accounted for. The onset of cleavage is taken to occur when a cri tical value of the maximum principal stress is attained. The effect of weld strength undermatch or overmatch is investigated for a comparison material , and analyses are also carried out based on experimentally determined flow strength variations in a weldment in a HY100 steel. The predicted work to fracture shows a strong sensitivity to the location of the notch relative t o the weld, with the most brittle behavior for a notch close to the narrow heat affected zone. The analyses illustrate the strong dependence of the tr ansition temperature on stress triaxiality. (C) 2000 Elsevier Science Ltd. All rights reserved.