Elucidating the role of stress-induced martensite on the tensile behaviour of metastable β Ti-10V-2Fe-3Al alloy

Rastogi, A and Kalyan, D and Makineni, SK and Neelakantan, S (2024) Elucidating the role of stress-induced martensite on the tensile behaviour of metastable β Ti-10V-2Fe-3Al alloy. In: Materials Characterization, 207 .

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Abstract

Stress-induced martensitic transformation (SIMT) during loading in metastable alloy systems result in strength-ductility enhancement via transformation-induced plasticity (TRIP). The present study aims to investigate the influence of stress-induced martensites (SIM) on the tensile behaviour of metastable β Ti-10 V-2Fe-3Al (Ti-1023) alloy. The solutionized, and thermo-mechanically processed (i.e., cold rolling and annealing at 820 °C for 5 to 30 min) condition of Ti-1023, with single β phase microstructure, has been considered. The β grain size of solutionized Ti-1023 was ~625 μm, while the thermo-mechanically processed Ti-1023 was in the range of ~48 μm to ~106 μm as function of annealing time. The room temperature tensile behaviour of considered samples show SIMT, which results in strength enhancement (~7.5), along with an increase in the trigger stress (~30) as a function of β grain size (i.e., ~48 μm to ~625 μm). However, the strain to failure show a significant decrease. A detailed microstructural characterization indicates the relation of SIM formation capability with β grain size. For finer β grain size, SIM displays a pronounced embrittling effect on the Ti-1023 tensile behaviour. Fracture surfaces show distinct regions with lath morphologies, which are further confirmed by surface as well as cross-sectional transmission electron microscopy (TEM) of the tensile fractured surfaces, illustrating the embrittling effects induced by SIM. In comparison, the dislocation-induced plasticity regions in the surrounding remnant β matrix result in dimple morphology. Thus, the coupling of enhanced martensite transformability, with reduced grain size, and the eventual decrease in martensitic laths spacing (i.e., from ~48 μm to ~7 μm), increase the density of martensite/matrix interfaces and the embrittling action. This results in pronounced dislocation pileups and formation of multiple martensitic variants facilitating premature failure by micro-void nucleation (at the martensite/matrix interface), growth and coalescence mechanism. The observations suggest that grain boundary engineering be optimized in order to fully exploit SIM's potential in enhancing the strength-ductility relation in Ti-1023 alloy. © 2023 Elsevier Inc.

Item Type:	Journal Article
Publication:	Materials Characterization
Publisher:	Elsevier Inc.
Additional Information:	The copyright for this article belongs to Elsevier Inc.
Keywords:	Aluminum alloys; Cold rolling; Energy dispersive X ray analysis; Fracture; Fracture mechanics; Grain size and shape; High resolution transmission electron microscopy; Iron alloys; Martensite; Martensitic transformations; Morphology; Nanoindentation; Plasticity; Stress analysis; Tensile strength; X ray diffraction analysis, Fracture behavior; Grainsize; Matrix interfaces; Metastables; Nano indentation; Stress induced martensitic transformation; Stress-induced martensite; Tensile behaviors; Ti-1023; Titanium (alloys), Titanium alloys
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	29 Feb 2024 05:33
Last Modified:	29 Feb 2024 05:33
URI:	https://eprints.iisc.ac.in/id/eprint/83713

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