Numerical investigation by finite element simulations of the ball punch test: Application to tempered martensitic steels

The effects of the post-yield behaviour on the shape of small ball punch test (SBPT) curves were investigated with finite element simulations from which the load–deflection curves were extracted. We have shown the general yield load defined on the ball punch curves depends on the post-yield behaviour and that the usual linear calibration between the yield load and the yield stress may lead to erroneous estimations of the irradiation hardening. A new calibration procedure has been proposed to determine the yield stress from a ball punch curve that makes use of empirical parameters that minimizes the effects of the post-yield behaviour which influence the overall shape of the ball punch test from the very beginning of the tests.