Recrystallization Behavior and Texture of High-Purity Niobium for SRF Cavity

Abstract

Deformation and recrystallization behavior of pure niobium was investigated in order to clarify the origin of its low hydro-formability despite its high ductility comparable with pure iron. Pure niobium exhibited lower strain hardening in cold rolling compared with pure iron. Furthermore, in post-deformation annealing, the hardness of niobium decreased monotonously with increasing temperature, and a typical sharp drop by recrystallization was not evident. This softening behavior was contrasted with the pure iron. It is suggested that niobium exhibits the so-called in-situ recrystallization because of its low elastic modulus and low accumulative plastic strain energy. The low hydro-formability of pure niobium sheets or tubes can be caused by its low strain hardening and in-situ recrystallization which is associated with this recovered residual rolled texture.