Abstract
The efficacy of hot isostatic pressing (HIP) for enhancing fatigue performance is investigated for additively manufactured (AM) Ti-6Al-4V. The limitations of HIP are probed by varying the initial material state via the selection of AM system, powder chemical composition, and process parameters. We demonstrate that the fatigue performance of HIP’d AM Ti-6Al-4V depends on the as-built quality of the material. Differences in common material attributes, such as pre-HIP defect populations or post-HIP microstructure morphology, are shown to be insufficient to explain the observed discrepancies in performance. This implies that additional microstructure attributes or localized deviations from the expected structure control the failure of this material. Finally, HIP parameters outside ASTM recommendations were explored, where a reduced temperature and high-pressure treatment yielded significantly improved fatigue performance.
Highlights
Ti-6Al-4V is an α + β titanium alloy with an excellent combination of specific strength, corrosion resistance, fracture toughness, and biocompatibility [1–3]
Due to the unique thermal history experienced by the material during additive manufacturing (AM) fabrication, a disparate set of material properties are observed in AM Ti-6Al-4V when compared to traditional fabrication methods [8]
Despite significant progress to better understand, predict, improve, and monitor the AM process, the control of build defects is not yet sufficient to assure safety in demanding fatigue critical applications [10–20]. Post processing treatments, such as hot isostatic pressing (HIP) followed by surface machining, have been used in an effort to minimize the negative implications of build defects [21–23]
Summary
Ti-6Al-4V is an α + β titanium alloy with an excellent combination of specific strength, corrosion resistance, fracture toughness, and biocompatibility [1–3]. Due to the unique thermal history experienced by the material during AM fabrication, a disparate set of material properties are observed in AM Ti-6Al-4V when compared to traditional fabrication methods [8] For this popular structural alloy, controlling the formation of microscopic build defects during fabrication can be key towards the goal of reliable fatigue performance [9]. Despite significant progress to better understand, predict, improve, and monitor the AM process, the control of build defects is not yet sufficient to assure safety in demanding fatigue critical applications [10–20]. In such cases, post processing treatments, such as hot isostatic pressing (HIP) followed by surface machining, have been used in an effort to minimize the negative implications of build defects [21–23]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
