Controlling martensitic decomposition during selective laser melting to achieve best ductility in high strength Ti-6Al-4V

By A. Zafari, M. Barati, K. Xia. Materials Science & Engineering: A, 2019

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Abstract Systematic variations of the exposure time and point distance of the pulsed laser used in selective laser melting (SLM) of Ti-6Al-4V resulted in three representative microstructures: the fully martensitic α', the near-α' containing a small amount of isolated β, and the fully lamellar α/β. The energy density in SLM determines the steady-state temperature in a deposited layer reached by balance between heat input from the subsequent layers and heat loss into the previous ones. A critical energy density was revealed below which no in-situ α' decomposition occurred. On the other hand, the in-situ formation of fully lamellar α/β was obtained using energy density higher than this critical value, leading to a steady-state temperature above that for α' decomposition for a sufficiently long duration. All three microstructures exhibited high tensile yield strength of 1100–1150 MPa, with excellent tensile elongation in the fully martensitic α' (~15%) and fully lamellar α/β (~12%) but significantly lower ductility in the near-α' (

Subfields: Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/4435fed9747a80379e3239dff6eb03f36391b346