Effect of grain size on the recrystallization kinetics and crystallographic texture of unidirectionally rolled Ti-15V-3Cr-3Al-3Sn alloy

Abstract

In the present work, Ti-15V-3Cr-3Al-3Sn (Ti-15333) samples were solution annealed (SA) at two different temperatures (800 °C for 30 minutes and 1000 °C for 15 minutes) to investigate the effect of initial grain size (GS) on the cold rolling and recrystallization behavior. Average grain size (AGS) for samples SA at 800 °C and 1000 °C was 87±7.82 μm and 177±4.36 μm, respectively. Both the samples were cold rolled unidirectionally (UDR) upto 80 % thickness reduction, subsequently followed recrystallization at 780 °C. UDR samples showed elongated grain structure with a preferential formation of shear bands (SBs) in some grains. Formation of SBs was more prominent in coarse AGS sample and these bands were also found to be orientation sensitive. The frequency of occurrence of SBs was more in γ-fiber (ND//<111>) grains and Dillamore’s plastic instability criterion was used to explain their preferential occurrence in γ-fiber. Recrystallization was done at 780 °C, for various time periods ranging from 30 s to 30 minutes). 80 % UDR samples showed the formation of strong α- and γ-fibers in both the cases. Full recrystallization was attained within 10 minutes for the initial fine grained 80% UDR sample, and it exhibited a continuous γ-fiber texture. In contrast, initial coarse grained 80% UDR sample took 20 minutes to achieve complete recrystallization, and it showed a discontinuous γ-fiber texture. Notably, the {111}<112> texture component of the γ-fiber was prominently evident in both cases, while the α-fiber was entirely absent for both conditions.