Effect of Heat Treatment and the Fabrication Process on Mechanical Properties of Zr-14Nb Alloy

The microstructure and mechanical properties of thermomechanically processed Zr-14Nb alloy with low magnetic susceptibility were investigated in this study. The stress-strain curves of Zr-14Nb alloy were classified as higher or lower work-hardening types depending on the thermomechanical process. Serration was observed in curves of the higher work-hardening type. SEM-EBSD analysis indicated that {332}<113> twinning should form at the hands that appear after tensile testing. On the other hand, no serration appeared in the lower hardening rate curves. The mechanical properties of centrifugally cast Zr-14Nb alloy with a lower work-hardening rate possessed moderate tensile strength and high elongation because of the formation of the isothermal re phase during cooling after centrifugal casting, although the tensile strength was increased and the elongation was decreased with increase of the isothermal w phase formed after aging. The magnetic susceptibilities of thermomechanically processed Zr-14Nb alloys were still one-third lower than those of Ti-6A1-7Nb. Accordingly, the mechanical properties of Zr-14Nb can be controlled by thermomechanical processing while keeping low magnetic susceptibility.