Extended ductility and cavitation in a high manganese stainless steel

Abstract

The deformation behaviour of high manganese stainless steel has been studied by uniaxial test at temperatures ranging from 600° C (873 K) to 850° C (1123 K) and at strain rates of 2.8 × 10⁻⁴ to 1.4 × 10⁻² sec⁻¹. The maximum elongation (228%) is found to occur at 750° C (1023K) and with an initial strain rate of 4.16 × 10⁻⁴sec⁻¹. Cavitation takes place throughout the gauge length of the specimens, with most of the cavities being located near to the fracture region. The cavitation phenomenon has been studied using metallography and the results have been analysed using a semi-empirical model of cavity growth. The cavity growth at high temperatures may be controlled either by diffusion or by a power-law growth process. For smaller cavity sizes, a diffusional growth mechanism is operative and there is a transition to a power-law growth process at a critical cavity radius, r_c. The value of r_c is found to increase with increase in temperature and decrease in strain rate. The computed critical cavity radii lie in the range of 0.7 to 2µm for the range of temperatures and strain rates used in this investigation.