High temperature plastic deformation behavior and constitutive equation of pure nickel

Severe deformation behaviors of pure nickel N6 plate under different temperatures and deformation rates were investigated by single press test on the Gleeble-3800 thermo mechanical simulation through orthogonal experiment. The results showed that the flow stress of the plate under the severe deformation increased again after the appearance of steady flow stress; with the rise of deformation temperature, the flow stress went down under the same deformation rate; with the rise of deformation rate, the flow stress went up under the same temperature, which indicated the sensitive relationship of flow stress with deformation temperature and strain rate. With the deformation rate of 40 s-1, the flow stress curve became instable and undulated, which showed that under the condition of large strain rate, pure nickel N6 plate had obvious rheological instability characteristics. The linear regression was carried out with experimental data, and the hyperbolic sine function material parameters of the constitutive equation of style were obtained, and then the strain was quadratic fitted with the material parameters, and constitutive equations of flow stress, deformation temperature, deformation rate, and the strain for the pure nickel N6 plate during hot deformation were built. As verified, the constitutive equations were able to reflect the characteristics of the real deformation of the pure nickel N6 plate. ©, 2015, Editorial Office of Chinese Journal of Rare Metals. All right reserved.