A comparative study of constitutive equations for the creep deformation of HP40Nb micro-alloyed steel

Creep behavior of HP40Nb micro-alloyed steel was examined at temperatures ranging from 923 K to 1323 K and stress levels in the range 47 MPa to 120 MPa. The effect of higher stress or temperature reduced primary and secondary creep region. The paper compared two different forms of constitutive models: power law approach and Dorn approach to predict the creep behavior of the investigated steel. Experimental data was used to determine constitutive parameters. The results revealed that minimum creep rate depends on applied stress and test temperature. Stress exponent and activation energy for creep of power law expression decreased non-linearly with the increase in temperature and stress, respectively. The minimum creep rate data calculated using Dorn approach shows good agreement with the experimental data.