Zirconium niobium alloy is heat treatment strengthened alloy, quenching - cold processing aging treatment can also improve the corrosion resistance.
Before leaving the factory, the chemical composition, corrosion performance, mechanical performance, surface quality, hydride orientation, metallographic structure, dimensional deviation, non-destructive flaw detection and other indicators of the tubes and bars for product performance inspection shall be evaluated to ensure that the chemical composition and corrosion performance indicators of the tubes and bars are the same and the mechanical performance indicators are similar. The thermal neutron capture cross section of zirconium is very small, which is one of the excellent nuclear physical characteristics. The thermal neutron capture cross section of zirconium tin alloy tube rod is not greater than 0.24b, and that of pure zirconium tube rod is not greater than 0.18b. In addition, the ability to resist radiation growth is excellent, which is another nuclear physical characteristic of zirconium. It is related to the working condition of the reactor, the cold processing capacity and crystal texture of zirconium.
Zircaloy tube rod should be sampled before leaving the factory, in 400 ℃ and 10.3 MPa steam 3 or 14 days corrosion test, and measure the weight should be less than 3 days 22 mg/dm2, weight should be less than 14 days 38 mg/dm2, generated on the surface of the black bright protective film. The mechanical properties of ex-factory re-crystallized zirconium tin alloy tubes are: the room temperature strength limit is greater than 413MPa, the yield strength is greater than 241MPa, the elongation is greater than 20%. The mechanical properties of high-temperature strength and the stress-eliminating state tubes are determined by the supplier and the supplier through consultation. Although the corrosion weight of zirconium and niobium alloy tubes is slightly larger than that of zirconium and tin alloy tubes, the corrosion strength of zirconium and niobium alloy tubes is higher.
Test, zirconium and zirconium zircaloy, niobium alloy after corrosion test sample weight gain can usually be described by the empirical formula: Δ m = Ktn, or lg Δ m = K + NLGT, type of Δ m weight (mg/dm2); T represents the experimental time, and K and n are specific coefficients.
