Copyright Dr. Shibayan Roy

Orientation dependent spheroidization response and α-phase texture evolution during sub β-transus annealing of Ti-6Al-4V alloy

Spheroidization response of the constituent α-colonies in a warm-rolled Ti-6Al-4V alloy is known to differ significantly during sub β-transus static annealing. In this communication, the same has been examined for the first time from an orientation perspective by coupling slip activation, boundary formation and interfacial energy anisotropy of individual α-colonies. The orientation of the α-colonies with reference to the loading directions dictates the nature of slip activation (single versus multiple slip; basal or prism <a> slip plus pyramidal <c+a> slip) during (α+β)-rolling in the first place. During subsequent static (α+β)-annealing, this factor initially translates into the relative ease of boundary splitting and thermal grooving for them. Formation of longitudinal boundaries then set the order of spheroidization for diffusion based coarsening processes during long term annealing. Anisotropy in interfacial energy as a consequence of loss of coherency during prior deformation creates further orientation dependency in the spheroidization sequence. As a concomitant effect, sub β-transus annealing results in significant weakening of basal fibre (ND//<0001>) and complementary strengthening of prism fibre (RD//<100>) from prior-rolled texture. This modification is conjugated to the orientation dependent spheroidization of primary α-phase (αp) which makes a distinction between their relative contribution to these texture fibres. Orientations proximity between secondary α (αs) and stable αp-phases further contributes to this texture transition.

Dr. Shibayan Roy

Assistant Professor

Materials Science Center

Indian Institute of Technology

IIT-Kharagpur 721302

India

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Dr. Shibayan Roy
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