Experimental-numerical determination of the Taylor- Quinney coefficient

During plastic deformation of a metal, a part of the plastic work is stored in the material due to local distortion of the crystal lattice, while the remainder is dissipated as heat. The part of the plastic work dissipated as heat can be observed on a macroscopic scale through thermal measurements in high strain rate experiments. Typically, this fraction of plastic work converted into heat is assumed to be constant and around 90%. In this study, we have performed tension tests at a constant crosshead velocity of 0.6 mm/s on flat notched specimens from a DP600 steel material. Digital image correlation (DIC) was used to apply virtual extensometers spanning the length of the notched area. Furthermore, an infrared camera was used to measure the temperature increase over the same area as monitored by DIC, enabling correlation between temperature and displacement. These temperature-displacement curves were used as the target curves in thermomechanical simulations to obtain the Taylor-Quinney coefficient as a function of the equivalent plastic strain. It was found that the Taylor-Quinney coefficient exhibits quite large variations during the experiment, ranging from a minimum of about 0.5 in the beginning of the test, to about 0.95 at the end of test.