A process for the production of a cold-worked blank or a composite tube of Zr alloy internally lined with a layer of non-alloyed Zr comprises: (a) transforming an ingot of zirconium alloy to bar form by hot working (rolling and/or forging); cutting the worked bar obtained into billets, boring a substantially coaxial hole in a billet and machining that billet; and quenching with water from the range beta either (i) the worked bar before the operation of cutting it up into billets, or (ii) at least one billet that has been cut up, before or after piercing; (b) transforming an ingot of non-alloyed zirconium containing at least 250 ppm of Fe; cutting the worked bar obtained into billets or portions; piercing a billet or portion, quenching it with water before or after piercing, from a temperature of between 880 and 1050 DEG C, and extruding it in the range alpha in tube form; and finally (c) assembling the tube of non-alloyed zirconium inside the substantially coaxial hole in the billet of zirconium alloy; extruding the resulting assembly in the range alpha in the form of a composite extruded blank; and cold rolling the composite extruded blank and subjecting it to heat treatment so as to produce one or more composite worked blanks and then composite sheath tubes. The composite cold-worked tubular blanks of zircaloy 2 internally lined with non-alloyed Zr, and the composite sheath tubes obtained, are novel and are distinguished by their Fe content and their fine grain.
展开▼
