PURPOSE: To manufacture a Zr alloy improved in bendability by successively executing heating in the β single phase range, cooling to the α single phase range, heating and working treatment in the α single phase range under specified conditions to a Zr alloy having specified content of Cr and Fe and subjecting it to recrystallization annealing.
CONSTITUTION: A Zr alloy contg., by weight, 0.01 to 0.10% Cr and the balance Zr with inevitable impurities, in which the amt. of Fe in the impurities is regulated to ≤0.125% and satisfying Fe(%) ≤6.5×Cr(%) is held under heating till the elements to be incorporated satisfactorily enter into solid soln. in the βsingle phase temp. range. Next, this Zr alloy is cooled to the α single phase temp. range at ≥0.2°C/sec cooling rate and is held in the α single phase temp. range of ≥650°C for the time satisfying the condition in the inequality [(t) denotes time (hr) and T denotes temp. (°C)]. Furthermore, the Zr alloy is subjected to working for ≥2 times in the above α single phase temp. range each at ≥25% draft. After the working at ≥70% whole draft, the alloy is subjected to recrystallization annealing at the recrystallization temp.(about 550°C) or above in the α single phase range. In this way, the Zr alloy excellent in bendability can be obtd.
SHIDA YOSHIAKI
KODAMA TSUYOSHI
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