On the transformation temperatures of Ti-6Al-4V: Effect of oxygen pick-up during Laser Powder Bed Fusion - Mines Saint-Étienne Access content directly
Journal Articles Materials Characterization Year : 2023

On the transformation temperatures of Ti-6Al-4V: Effect of oxygen pick-up during Laser Powder Bed Fusion

Abstract

Ti-6Al-4V (Ti64) parts manufactured by Laser Powder Bed Fusion (L-PBF) exhibit a fine martensitic microstructure and significant residual stresses that are detrimental for their mechanical performance. Consequently, post-processing heat treatments are necessary to relieve these internal stresses and achieve a microstructure adequate for the mechanical requirements. Given the variations in powder compositions and processing parameters, there is a large scattering of physical properties of both as-built and heat-treated parts. In this context, this study quantifies the link between interstitial contents (specifically oxygen and nitrogen) and the transition temperatures of as-built parts, using as-atomized pre-alloyed powders for reference. The martensite decomposition temperature and beta transus temperature are assessed using high-temperature X-Ray diffraction and differential scanning calorimetry for both the powder and as-built parts. It was found that the martensite that composes the as-built microstructure can be decomposed into a stable α+β structure at temperatures exceeding 490 °C. Oxygen and nitrogen pick-up occurs during the L-PBF process, leading to an elevated beta transus temperature in as-built parts relative to the original powder. This insight provides a guide for optimizing post-processing heat treatments for Ti64 as-built components.
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Sunday, March 24, 2024
Embargoed file
Sunday, March 24, 2024
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Dates and versions

emse-04444330 , version 1 (08-02-2024)

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Quentin Gaillard, X Boulnat, Sophie Cazottes, Sylvain Dancette, Christophe Desrayaud. On the transformation temperatures of Ti-6Al-4V: Effect of oxygen pick-up during Laser Powder Bed Fusion. Materials Characterization, 2023, 205, pp.113323. ⟨10.1016/j.matchar.2023.113323⟩. ⟨emse-04444330⟩
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