Effects of heat-based sequential post-processing on microstructural evolution and micro-defect closure in LPBFed Ti-6Al-4V alloy
Abstract
Components produced by laser powder bed fusion (LPBF) often introduce defects like pores and lack of fusion due to rapid solidification during fabrication, thus reducing the mechanical performance of fabricated alloys. While post-processing can alleviate these heterogeneities, research on micron-scale defects remains limited. This study investigates the coupled evolution of microstructure and micro-defects in LPBFed Ti-6Al-4V subjected to an HT-based sequential post-processing route. The as-built microstructure, consisting of acicular α’ martensite, a minor β phase, and numerous micron-sized pores, transformed into a near-basketweave α + β structure after annealing (HT). Subsequent hot isostatic pressing (HT+HIP) and additional annealing (HT+HIP+HT) led to thickened α lamellae and increased β fractions, enhancing ductility at the expense of strength. During HT, diffusion and phase transformation promoted pore spheroidization and shrinkage, though adjacent pores occasionally coalesced. HT reduced the detectable pore number density but did not remove all residual pores within the resolution range of the present CT system. In contrast, subsequent HIP reduced the residual pores to below the CT detection limit through shrinkage, collapse, closure, and welding. No pore reappearance was detected during the final annealing step within the same CT resolution range. These results indicate that HT modifies the α/β microstructure and reduces the detectable pore population, whereas HIP is more effective in reducing micron-scale pores in LPBFed Ti-6Al-4V.
Keywords
laser powder bed fusion, micro-defects, microstructure, post-processing, Ti-6Al-4V
Document Type
Journal Article
Date of Publication
7-10-2026
Article Number
189454
ISSN
09258388
Volume
1076
Publication Title
Journal of Alloys and Compounds
Publisher
Elsevier
School
Centre for Advanced Materials and Manufacturing / School of Engineering
Funding Information
This work was financially supported by the National Key Research and Development Program of China (No. 2023YFB3712200), the National Natural Science Foundation of China (No. 52271108, 52405396) and the ECU DVC strategic research fund (No. 23965).
Copyright
subscription content
Content Type
Metadata only
Recommended Citation
Zhang, H., Xing, H., Huang, H., Lin, K., Zhang, K., RenXu, J., Zeng, H., Wang, H., Yang, Y., Yuan, Y., & Zhang, L. (2026). Effects of heat-based sequential post-processing on microstructural evolution and micro-defect closure in LPBFed Ti-6Al-4V alloy. Journal of Alloys and Compounds, 1076, Article 189454. https://doi.org/10.1016/j.jallcom.2026.189454