Loss of stability for the process of plastic deformation with a complex stressed state

Basic preconditions are presented for considering the stability of the plastic deformation process in evaluating the ultimate deformation and strength properties of structural materials in tubular specimens under conditions of a complex stressed state. Calculated dependences are provided for calculating these characteristics. Results of experimental studies are analyzed for heat-resistant steels 15Kh2MFA, 15Kh2NMFA, and VK-2 (KP-100) (the latter simulates radiation embrittled steel 15Kh2NMFA) with different principal stress ratios in the temperature range 20–350°C. Calculated values of ultimate stresses and strains are compared with experimental data. The possibility of using the results of experiments carried out with stepwise loading as a basis for calculating the endurance under cyclic loading conditions with a complex stressed state is substantiated.Translated from Problemy Prochnosti, No. 10, pp. 3–8, October, 1991.