Patent ID: 6902634
Filing Date: 2005-06-07
Classification: C22C,C22F,G21C,Y02E

Abstract:
1. A method for manufacturing a niobium-containing zirconium alloy for use in nuclear fuel cladding tubes, wherein the alloy comprises niobium in a range of 1.1-1.7 wt %, oxygen in a range of 600-1600 ppm, silicon in a range of 80-120 ppm, and the balance being zirconium, the method comprising steps of: melting an ingot of the alloy component; forging the ingot at a β phase temperature above 1000° C.; β-quenching the forged ingot in water after performing a solution heat-treatment at β phase range above 1000° C.; hot-working the β quenched ingot at a temperature of 600-640° C.; vacuum annealing the hot-worked ingot at 570-610° C.; cold-working the annealed ingot in three to four passes, with an intermediate annealing step performed between each pass, wherein the intermediate annealing step is performed at a temperature of 570-610° C. in a vacuum for a duration of 3-100 hours; and final annealing the cold-worked ingot at a temperature of 470-580° C., whereby the niobium concentration in the alloy decreases from the supersaturation state to the equilibrium state to improve the corrosion resistance of the alloy, wherein the temperature and duration of the intermediate annealing step are such that the β-Nb precipitates in the alloy are limited to a maximum average diameter of 80 nm and an accumulated annealing parameter(ΣA) is limited to a maximum of 1.0×10-18 hours, wherein ΣA=Σ ti exp(−Q/RTi), ti being the annealing time of the i-th step after β-quenching, Ti is the annealing temperature of the i-th step after β-quenching, Q is the activation energy and Q/R is equal to 4000K.