Treatment process for a zirconium alloy, zirconium alloy resulting from this process and parts of nuclear reactors made of this alloy

A treatment process for a zirconium alloy for use in a nuclear reactor, comprising:

• preparing a zirconium alloy ingot, the zirconium alloy ingot having a composition of which is in weight % or weight ppm:
• 0.40%≤Nb≤1.05%;
• traces ≤Sn≤2%;
• (0.5 Nb−0.25) %≤Fe≤0.50%;
• traces ≤Ni≤0.10%;
• traces <(Cr+V) %<0.50%;
• traces ≤S≤35 ppm;
• 600 ppm≤O≤2000 ppm;
• traces ≤Si≤120 ppm;
• traces ≤C≤150 ppm;
• If 0.50%≤Nb≤1.05%, then (Cr+V) %≤(0.2 +3/4Fe−1/4Nb) %;
• and
• the remaining being Zr and unavoidable impurities;
• at least one step of reheating and hot shaping the zirconium alloy ingot;
• at least one cycle of cold rolling-annealing steps on the zirconium alloy ingot after the at least one step of reheating and hot shaping, a last annealing of the at least one cycle of cold rolling-annealing steps being a final annealing step which gives a product formed therefrom a final stress-relieved, partially recrystallized or completely recrystallized condition,
• the annealing of at least one of the cold rolling-annealing steps being performed at a temperature comprised between 650° C. and the lowest of either 700° C. or (710−20×Nb %)° C., and the annealings of the other cold rolling-annealing steps, if any, being performed at a temperature not higher than 600° C.