Measurement of temperature coupling by thermovision and constitutive relation at high strain rates for the dual phase sheet steel

The paper presents an original experimental set-up to study the thermo-visco-plastic behavior of a dual phase sheet steel DP 600. It is also shown how to determine the temperature gradients during shear test at different strain rates varying from $10^{-4}\le \dot{\gamma}\le 10^{-3}$ s$^{-1}$ up to large shear strains, $\gamma\approx 1$. The temperature increments are measured by an infrared camera recording the infrared radiation emitted from the shear zone during the process of plastic deformation. Due to combination of a fasthydraulic machine and the direct impact technique with the Hopkinson tube, [1], together with an infrared camera, it was possible to find the stress evolution with the shear strain and the local temperature in the shear zone [2]. At the same time it was possible to estimate the strain rate when the adiabatic shear bands appear. Moreover, an original thermovisco- plastic constitutive relation is proposed and compared with that by Johnson-Cook, [3]