Plastic low stress and physically based constitutive model of four newer naval vessel steels
4种新型舰艇钢的塑性流变应力及其本构模型

The mechanical behaviors of the steels HSLA-65, DH-36, AL-6XN and Nitronic-50 were systematically studied at strains over 40%, a temperature range of 77-1000 K and strain rates of 0.001 to 8000 s-1.The results are as follows (1) plastic flow stresses of the four steels are all very sensitive to the temperature and strain rate, the flow stresses increased with decreasing temperatures and increasing strain rates; (2) with plastic strain increasing or changing, the temperature history remarkably evolved the microstructure of fcc metals; (3) dynamic strain aging occured in proper temperature and strain rate region. With increasing strain rate, the temperature region of dynamic strain aging will shift to higher. Taking into account these phenomena, based on the mechanism of dislocation motion, including the effect of viscous drag on the motion of dislocations, physics based model was given in which the dynamic strain aging effects were excluded. Comparing the results predicted and measured, good agreement is obtained for the plastic flow stresses of these steels in a wide range of temperatures and strain rates.