Two different methods of measuring ductile damage for stainless steel 316L

Damage is a progressive physical process, which at last leads to failure. During the damage process, material experiences some changes such as nucleation, growth, and coalescence of microscopic voids and microcracks. If the metal material is under the plastic strain, some defects like voids and microcracks are created. Increasing the plastic strains, these defects develop and eventually crack is created in the material which causes fracture in it. Therefore, measuring the damage is very important and various methods have been proposed to determine the damage in materials yet. In this paper first, different methods of estimating the ductile damage are presented and then, ductile damage for stainless steel 316L is determined, using the measurement of elasticity modulus and also measurement of velocity of ultrasonic wave propagation methods. Finally, value of critical ductile damage parameter for the material is calculated by each of these methods and compared.