Macrostructures and mechanical properties in laser melting deposited titanium alloy plate at different thickness positions

Abstract

Mechanical properties, including tensile properties and fatigue crack growth behaviors, and their relationships with macrostructures at different thickness positions in plates of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe, are experimentally investigated in this paper. It is observed that there display obvious differences in macrostructure features between overlap zones and non-overlap zones along thickness direction, which leads to anisotropies and heterogeneities of tensile properties including yield stress, tensile strength and total elongation. In fatigue crack growth tests with thin compact tension specimens at different thickness positions, crack paths are deviated from mode I with varying angles and fatigue crack growth rates display obvious fluctuations, which are mainly caused by the macrostructure features in overlap zone. In the end, evaluation methods are discussed for fatigue crack growth behaviors from the perspective of mechanics-materials interactive mechanisms, which helps strive for the future processing-material-structure-property-evaluation paradigm for additively manufactured metal structures.