A durability analysis of a mechanical component generally requires accurate numerical simulations. For this purpose, the adopted cyclic plasticity material model should follow as closely as possible the material behavior observed during experimental testing. This work presents calibration of the isotropic material model for a 42CrMo4 steel, based on a series of cyclic fully-reversed tension-compression strain controlled tests performed at different strain amplitudes. Stress-strain cycles were recorded until end of each test with the goal to capture the isotropic stabilization effect of the material. As the isotropic model calibration gave poor results, if the exponential law proposed by Voce is adopted, an alternative Three parameters (TP) isotropic model is thus considered. The comparison with the experimental results show that the TP model fits significantly better the experimental results in almost all the considered cases. A possible justification of such improvement seems to be related to the fact that the equation governing the TP model contain a parameter that controls also the slope of the “S-shape curve” which describes the evolution of the material from initial to stabilized condition.