Investigations on the effect of secondary treatments on Ti48Al2Cr2Nb alloy manufactured by electron beam powder bed fusion method

Date

2025-12-01

Author

Bilgin, Guney Mert
Ozer, Seren
Davut, Kemal
Esen, Ziya
Dericioğlu, Arcan Fehmi

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As-built Ti48Al2Cr2Nb alloy samples produced by electron beam powder bed fusion (PBF-EB) exhibited notable brittleness. The low ductility was attributed to coarse γ bands aligned perpendicular to the building and tensile direction. Additionally, variations in aluminum content and hardness between the coarse colonies and fine γ/α2 lamellae contribute to this phenomenon. Electron backscattered diffraction (EBSD) studies revealed a higher amount of dislocation density and inherent strain after PBF-EB manufacturing. Hence, usage of Ti48Al2Cr2Nb alloy in the as-built condition in aviation applications with high loads and demanding environments is not found to be viable. To eliminate these negative aspects and make PBF-EB produced Ti48Al2Cr2Nb alloy available for demanding applications, two distinct post-processing heat treatments; namely, hot isostatic pressing (HIP) and annealing heat treatment (HT) were employed at 1200 °C. A comprehensive characterization covering microstructure analysis, EBSD, fracture surface examination, as well as room and high-temperature tensile tests allowed determination of the effect of post-processes. HIPing altered the banded structure observed in the as-built samples by increasing the amount of α2 phase and grain size. On the other hand, HT made the banded structure more pronounced without significantly increasing the amount of α2 phase. HT also strengthened the texture, while HIPing introduced randomization of grains. On the other hand, complete recrystallization is achieved as a result of HT at 1200 °C for 2 h, whereas HIPing at the same temperature for 2 h induced only 80.5 % recrystallization. In both post-processes, dislocation density and inherent strain were reduced. Room temperature and high-temperature tensile tests demonstrated that both HIPing and HT eliminated the extreme brittleness of the as-built samples.

Subject Keywords

A. intermetallics (aluminides), B. mechanical properties, C. heat treatment, C. hot isostatic pressing, C. near–net–shape manufacturing, G. aero–engine components

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https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=105015301941&origin=inward
https://hdl.handle.net/11511/115901

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Department of Metallurgical and Materials Engineering, Article