Microstructure and texture evolution of pure molybdenum during hot deformation

Abstract

Microstructure and texture evolution of pure molybdenum prepared by powder metallurgy during the thermal mechanical processing were studied. Uniaxial compression tests were carried out on Gleeble-1500 thermal mechanical simulator in range of temperature (1100 ºC-1300 °C), strain rates (0.1 s−1-10 s−1) and true strain (0.3–0.6), respectively. The results show that the difference in deformation mechanism caused by temperature, strain rate and true strain has a great influence on microstructure and texture. Especially at 1300 °C, pure molybdenum will have obvious geometric dynamic recrystallization, and as the deformation progresses, the jagged high angle grain boundaries are close to each other and forming an equiaxed crystal. This equiaxed crystal structure is separated by a high angle grain boundary and the size of the equiaxed crystal is close to the subgrain size. In addition, this paper focuses on the deformation behavior of pure molybdenum under different true strains. There are two typical orientations of fiber texture. One is <100>//CD fiber texture, including {001} <100> cube texture and {110} <001> goss texture; other is <111>//CD fiber texture, including {112} <111> copper texture and {110} <111> texture. The increased distortion of the deformation provides a certain driving force for the rotation of the grain, prompting it to the preferred slip system, thereby weakening the texture resulting from the deformation. What’s more, the dynamic recrystallization behavior can significantly weaken deformed textures, especially for <111>//CD fiber texture.