Effect of β (110) texture intensity on α-variant selection and microstructure morphology during β→α phase transformation in near α titanium alloy

Abstract

In the present work, we investigated the texture evolution as well as the role of the β texture intensity on the α-variant selection and microstructure morphology during the α→β→α phase transformation in Ti60 alloy. Different microstructures and textures were obtained through forging the Ti60 bars into diameters of 45 mm denoted as D45 and 30 mm as D30. Subsequently, small samples with the same size cut from both bars were heat-treated above the β transus followed by furnace cooling and air cooling. We found that the β texture intensity, cooling rate, and variant selection affect both the texture intensity and microstructure morphology of the transformed α phase. The high temperature β phase exhibits stronger (110) parallel to axial direction fiber texture in the β annealed D30 bar than that for the D45 bar. A basketweave microstructure was found in the β annealed D45 bar after air cooling whereas a coarse α colonies populated by fine α lamellae formed in the D30 bar. For furnace cooled samples, the α texture is stronger than that in the air cooled sample in D45 bar whereas the intensities of the textures are very similar to air cooled sample in the D30 bar. The influence of the β texture intensity and variant selection on the α texture evolution were studied by comparing the four experimental results and simulation data. The effect of α variant number in a β grain on α texture intensity, base on variant selection, and the effects of β texture intensity on microstructure morphology are discussed.