Zirconium bar is an alloy tubular material made of zirconium and other metals. Because of zirconium's excellent nuclear properties and corrosion resistance, zirconium alloy tube rods are often used in nuclear fuel assemblies and reactor structures in water cooled reactors, which are important nuclear materials. Pure zirconium rods are mainly used to make chemical equipment because they are expensive and not used much. The chemical composition and application of the commonly used zirconium tube rods are shown in the table.
It is carried out in a vacuum furnace with a vacuum degree of 1×10-2 ~ 1× 10-3Pa. A thick size workpiece with a protective coating or cover intact allows rapid heat treatment in the atmosphere. The middle annealing temperature of zirconium alloy rod is about 700℃, recrystallization starts from about 500℃, and the grain becomes coarser at 600℃. The stress relief annealing of finished pipe was 450 ~ 500℃, and the recrystallization annealing of finished pipe was 530 ~ 600℃.
The zircaloy last intermediate annealing heat instead to beta or alpha high temperature quenching, again after the final cold working and heat treatment for finished products finished pipe material, better corrosion resistance, the reason may be that the finished tube small scattered, the second phase of microstructure and alloy element is added in the alpha - Zr content of solid solution in the matrix. The operation of the reactor shows that the zirconium alloy tube, which has been heat treated above, as the cladding tube of the nuclear fuel element, can mitigate the furuncu-like corrosion of the fuel cladding during the operation of the reactor. But because of quenching furnace pipe manufacturing and cleaning the surface of the tube after quenching difficulties, semi-finished pipes quenching is not easy to implement in the industry, so the producers tend to just before or after forging extrusion, the massive blank or alpha beta phase of drier heated nasty cold treatment, although the effect of this treatment is a bit poor, but still corrosion resistance can be optimized.
Zirconium and niobium alloy is a heat treatment alloy, and the corrosion resistance of zirconium and niobium alloy can be improved by quenching and cold processing.
