STRAIN-INDUCED TRANSFORMATION AND PLASTIC-DEFORMATION BEHAVIOR OF A 17CR-7NI-1AL STEEL AT HIGH HYDROSTATIC-PRESSURE

Mechanical properties of the material were found to be considerably changed by the pressure. The martensitic transition temperature decreased under pressure. The volume fraction of alpha -martensite induced by tensile deformation increased with strain but was suppressed by hydrostatic pressure. The yield stress increased with pressure. The yield surface became a nonlinear cone with a pointed apex. The stress-strain curve was considerably changed by pressure and was expressed by a modified identical-strain model (law of mixture) as a quantitative function. Uniform-strain limit increased with pressure. It was found that these changes were not caused by the mechanical effect of hydrostatic pressure but by its thermodynamic effects.