Tensile plasticity flow characteristics of DH36 steel and its constitutive relation

The tensile plasticity flow properties of high-strength structural steel DH36 were systematically studied at the temperature range from 293 to 800 K and the strain-rate range from 0.001 to 0.1 s-1 by using a quasi-static testing machine. And the high-strength structural steel DH36 underwent the strain over 25%. Then, the microstructures of the DH36 samples were analyzed by applying the scanning electron microscopy before and after deformation. The experimental results show that the third-type dynamic strain-aging (SA) phenomenon disappears in the test temperature range at the strain rates of 0.001 and 0.1 s-1, and the SA temperature rises with the increase of strain rate. And the disappearance of the third-type dynamic (SA) phenomenon is relevant to the precipitation strengthening of the alloy metals at grain boundaries and in grains. Finally, through systematically analysing the test data, a uniform constitutive model including the third type SA effects was built for DH36 steel. The results predicted by the built model are in agreement with the test data. It displays the built model can well predicate the plastic flow stresses of DH36 steel in the wide ranges of temperatures and strain rates.