Fatigue and Fracture Toughness of Ti-6Al-4V Titanium Alloy Manufactured by Selective Laser Melting

摘要

Additive manufacturing (AM) has gained significant interest in recent years as components can be produced to near net shape from metallic powders with data obtained directly from a 3D CAD model. Selective laser melting (SLM) is an AM technique which may be a viable alternative to conventional casting, forging and machining. The process does, however, result in significant residual stresses as well as significant surface roughness and some porosity, all of which may impair mechanical properties. Such defects need to be considered greatly under fatigue and fracture toughness behaviour especially for applications in the aerospace and biomedical industries. This project endeavours to measure the fatigue behaviour in the form of a fracture mechanics based "Paris equation" and fracture toughness of selective laser melted Ti6A1-4V alloy in two orientations, namely the fatigue crack grown (i) perpendicular and (ii) parallel to build direction. Results show that with stress relieving heat treatments, the fracture mechanics parameters of fatigue behaviour (Paris curve) and fracture toughness show strong correlation between SLM manufactured and conventional Ti-6A1-4V.