Effect of low-temperature plastic deformation of bcc-lattice metals on a stress-strain state at the crack-tip

摘要

We describe plastic strain at a crack-tip with the use of a physical criterion of creep in a complex stressed state proposed earlier. As distinct from von Mises criterion, the above criterion allows consideration of low-temperature deformation features of bcc metals. Simulation of loading was performed on a center-cracked plate specimen (400×160 mm) in plane deformation. It was shown that a decrease in shear resistance under the action of normal tensile stresses induced by low-temperature plastic deformation of bcc metals and alloys affects parameters of a stress-strain state at a crack-tip. This gives rise to an extension of the local plastic strain region, an enhancement of maximum strain at the crack-tip, and a change in the ratio between normal and tangential stresses in the plastic-flow region. Application of a physical criterion of creep is shown to be reasonable for stress-strain state calculations by the finite-element method in cracked bcc metals and alloys at low temperatures.