Impact of hot isostatic pressing treatments on the mechanical performance of EBMed Ti-6Al-4V alloy

• Published in: Materials characterization 2023-07, Vol.201, p.112962, Article 112962
• Main Authors: Tahri, C., Chauveau, Th, Hocini, A., Dirras, G., Bacroix, B.
• Format: Article
• Language: English
• Subjects: Additive manufacturing; Density; Electron beam melting; Hardness; Hot isostatic pressing; Microstructure; Porosity; Ti-6Al-4V
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2023.112962

The present study compares the efficiency of three different Hot Isostatic Pressing (HIP) post-treatments in reducing the density of defects in Ti-6Al-4V alloy parts fabricated by the Electron Beam Melting process. The HIP treatments are the standard HIP (T = 920 °C, P = 1000 bars, t = 2 h), a High-Temperature HIP (T = 1050 °C, P = 1000 bars, t = 2 h), and a two-step HIP (held above the β-transus, rapid quenching, and tempering) treatments. If it is observed that all three HIP treatments do seal internal porosity and increase the final density of the material, they are also shown to differ mainly in significant variations in morphology, porosity and hardness. It is also shown that the observed decrease in density is only partly linked to the decrease in porosity and mainly to the evolution of the chemical composition of the two phases constituting the Ti alloy through the HIP post-treatment as well as the quality of the crystalline structure. •A comparison of three different HIP treatments was performed on Ti-6Al-4 V pieces obtained by EBM.•All HIP treatments were successful in reducing the porosity and increasing the density of the samples.•Specificities of the different HIP experiments are translated in terms of final microstructure, phase percentages and mechanical properties.•The 2 step HIP treatment allows to reduce the overall grain growth.•The HT HIP treatment leads to a significant increase of the lath thickness and of the β phase percentage.