Recrystallization Textures in HCP Metals

Abstract

Recrystallization texture developments and their importance in relation tomechanical properties of commercially pure titanium (cp-titanium), pure magnesium and pure zinc have respectively been investigated in the present study. CP-titanium plates were subjected to unidirectional-rolling (rolling), accumulativeroll bonding (ARB) and cross-rolling followed by annealing at 600oC for a large range of soaking time starting from 10 s to 30 min. The samples were seen to develop almost similar texture when annealing was carried out beyond 5 min of annealing time. The initial (1125) 1100 texture present in the deformed structure got strengthened duringannealing of the samples under investigation. Further, [1125] fibre texture was observed in the samples at higher annealing times (> 10 min). It was further observed that the hardness of the grains close to basal orientation was higher compared to non-basal orientations and the estimated bulk mechanical properties of cp-titanium had a direct relationship with the volume fraction of basal grains/orientations.
Pure magnesium was subjected to cold (cross-) rolling and hot rolling of 90 % reduction in thickness. Cold rolled samples were then subjected to annealing at 200°C for a range of soaking times staring from 10 s to 30 min. A dominant basal texture was observed in the samples. It was also observed that pure magnesium had lower grain size, grain orientation spread, grain average misorientation and volume fraction of basal orientations when cold (cross-) rolled and annealed, compared to the hot rolled condition. It was further observed that an increase in deviation from basal orientation decreased the hardness of an orientation and magnesium with higher volume fraction of basal orientations had higher hardness.
As-cast pure zinc was subjected to cryo-rolling of 90% reduction in thickness. The rolled samples were then annealed at 50oC for different soaking times of 5 min, 10 min, 20 min and 30 min respectively. A dominant <1120 >fiber texture was observed in both rolled and annealed samples. Also type compressive twins were observed in the samples and these twinning was found to be significant in all the samples. The Vickers hardness of the samples was increased till 10 min of annealing time followed by decreased in hardness on further increasing the annealing time.