초록 ▼

A method for increasing the resistance of zirconium alloy tubing to nodular corrosion by applying a protective anneal at a temperature within a clearly defined temperature range. Also, a zirconium alloy tubing having such protective anneal is disclosed. The protective anneal comprises heating expose

A method for increasing the resistance of zirconium alloy tubing to nodular corrosion by applying a protective anneal at a temperature within a clearly defined temperature range. Also, a zirconium alloy tubing having such protective anneal is disclosed. The protective anneal comprises heating exposed surfaces of zirconium tubing to a temperature range bounded at its lower limit by the temperature Tc, Tc being the temperature which at equilibrium conditions a critical concentration of solute exists in .alpha.-matrices of the zirconium alloy to resist nodular corrosion, and bounded at its upper limit by the maximum temperature at which precipitates exist in association with the .alpha. and .beta. matrices in the particular zirconium alloy. In respect of Zircalloy-2 containing zirconium and the following metals by weight, namely 1.2-1.7% tin, 0.13-0.20% iron, 0.06-0.15% chromium, and 0.05-0.08% nickel, the lower temperature limit Tc is approximately 840 C and the upper limit is approximately 855 C.

대표청구항 ▼

1. A zirconium alloy tubing that is resistant to axial splitting and nodular corrosion, said zirconium alloy tubing comprising an .alpha.-matrix containing a solute, wherein said solute comprises at least one of iron, chromium, and nickel and is present above a critical concentration, said zirconium

1. A zirconium alloy tubing that is resistant to axial splitting and nodular corrosion, said zirconium alloy tubing comprising an .alpha.-matrix containing a solute, wherein said solute comprises at least one of iron, chromium, and nickel and is present above a critical concentration, said zirconium alloy tubing having been prepared by: heating a surface of said zirconium alloy tubing to a temperature within a temperature range bounded at its lower limit by a temperature Tc at which, under equilibrium conditions, said solute is present in said .alpha.-matrix in a concentration greater than said critical concentration, and bounded at its upper limit by a temperature of the (.alpha.+.beta.)/(.alpha.+.beta.+precipitate) transus inherent for the particular zirconium alloy; maintaining the temperature of said surface within said temperature range for a period of time greater than 2 seconds; and subsequently causing said temperature of said surface to be reduced at a rate sufficiently rapid to prevent substantial loss of solute concentration from said .alpha.-matrix.