Ductile Fracture Mechanisms in the High-strength Steel Hardox-400. Microscopic Observations and Numerical Stress-strain Analysis.

This report presents two hypotheses that aim to predict ductile failure due to void growth and due to shear. The former failure mechanism is predicted using measures of both the tridimensional stress level and plastic strain. The latter failure mechanism, which occurs along the shear lips, is predicted by the level of the maximum shear stress. Both hypotheses were verified by the stress and strain field analyses in front of the crack and scanning microscope observations of the fracture surfaces. A numerical 3D elastic-plastic analysis was conducted assuming finite strains. The material used was Hardox-400 ultra-high-strength steel.