Metal treatment – Process of modifying or maintaining internal physical... – Heating or cooling of solid metal
Patent
1998-11-04
2000-10-03
Sheehan, John
Metal treatment
Process of modifying or maintaining internal physical...
Heating or cooling of solid metal
C22F 118
Patent
active
061267627
ABSTRACT:
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 T.sub.c, T.sub.c 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 T.sub.c is approximately 840 C and the upper limit is approximately 855 C.
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General Electric Company
Sheehan John
LandOfFree
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