Combined rate-temperature effects in postnecking plasticity of A2-70 stainless steel

In this paper, a comprehensive study that integrates theoretical, experimental and FE analyses, elucidates the combined effect of strain, strain rate, and temperature on the mechanical response of A2-70 stainless steel. A wide series of tensile experiments on cylindrical specimens is presented, including low to high temperatures and quasi-static to dynamic rates. Opportune combinations of temperatures and strain rates are imposed in order to possibly separate and identify their respective effects on the flow curve of the material. The adopted experimental procedures based on neck-related measurements revealed the onset of secondary phenomena affecting dynamic tensile tests. Classical material models were found not suitable to correctly predict the complex elastoplastic deformation of this material. Thus, a new general material model is presented and used to account for the complex interplay between strain, temperature, and rate-dependent effects. Finite element simulations are conducted using both the proposed constitutive model and another classical model of dynamic hardening, to investigate and compare their predictive capability over the entire experimental campaign.