| 摘要 |
PURPOSE:To manufacture a superplastic Zr alloy having superior resistance to stress corrosion cracking and corrosion by hardening and aging a Zr alloy for the constituent parts of a nuclear fuel assembly for a nuclear fission reactor under specified conditions. CONSTITUTION:When a pipe 1 for cladding fuel pellets 2 for a nuclear fission reactor is made of a Zr alloy, the pipe 1 causes corrosion by a coolant and stress corrosion cracking by the thermal expansion of the pellets 2. In order to prevent the corrosion and stress corrosion cracking and to provide superplasticity, the Zr alloy is subjected to soln. heat treatment in the alpha+beta phase region (800-950 deg.C) of the alloy, cooled to 700 deg.C at <=100 deg.C/sec cooling rate, and aged at a proper temp. of 550-700 deg.C in the alpha-phase region. By this heat treatment, a cladding pipe of a Zr alloy causing no stress corrosion cracking and having superior resistance to corrosion by a coolant is obtd. |
