Damage accumulation and failure of HY-100 steel

Abstract

Strain-induced damage accumulation in the form of void volume fractions and number densities has been experimentally characterized for an HY-100 steel subjected to tensile failure over a range of temperatures (-85 °C to 25 °C), strain rates (10 -3 /s to 10 3 /s), and stress states (stress triaxiality ratios of 0.8 to 1.3). While the strain-induced evolution of damage is relatively insensitive to temperature and strain rate, it increases very rapidly with increasing stress triaxiality. In particular, the large body of void-growth data presented suggests the presence of an initially slow void-growth stage that can be described by a relationship with a form similar to that predicted by Rice and Tracey (but with increased dependence on stress triaxiality). The damage results also indicate a transition to rapid void growth (and imminent coalescence by a void-sheet mechanism) at a critical void volume fraction that decreases slowly with an increasing stress triaxiality ratio. A straightforward analysis, based on the experimental observations, relates the observed experimental dependence of failure strains on stress triaxiality for this steel.