Influence of cross rolling and heat treatment on texture and forming properties of molybdenum sheets

To produce molybdenum sheets or ribbons the metal has to be thermomechanically processed leading to characteristic deformation and recrystallization textures depending on the deformation and/or annealing conditions. The so produced textures have an impact on certain properties of the metal. The present work concentrates on the influence of different rolling processes and the last step of heat treatment on microstructure, texture and the mechanical properties of molybdenum sheets. Usually, unidirectional rolling leads to a strengthening of the main texture component, which for molybdenum is a weak α-fibre with a maximum at the rotated cube component {100} < 110>. This component leads to a strong anisotropy of the mechanical properties in the sheet plane. Cross rolling steps during the thermomechanical process increase the rotated cube component. To decrease the intensity of the rotated cube component and simultaneously increase the intensity of the γ-fibre, specific annealing stages of the final heat treatment were tested. The texture development during these annealing stages is discussed with regard to microstructural changes. The strong differences in the textures measured are reflected in the plastic anisotropy characterized by the Lankford parameters. The Taylor–Bishop–Hill theory is used to qualitatively explain the plastic anisotropy.