INFLUENCE OF PLASTIC STRAIN AND SUBSEQUENT ANNEALING ON THE STRUCTURE AND CORROSION RESISTANCE OF WELDED JOINTS IN ZIRCONIUM ALLOY.

It has been found that the corrosion resistance of welded joints of zirconium alloys containing 2. 5% Nb depends on their structural and phase composition. Joints with a phase constitution close to the equilibrium state of the alloy have the best corrosion resistance. Plastic strain of welded joints promotes acceleration of the process of breakdown of unstable alpha ' and beta //Z//r phases in the weld and in the heat-affected zone during subsequent low-temperature annealing and this leads to an increase of corrosion resistance. Surface plastic strain by roller burnishing, in conjunction with subsequent annealing in the ( alpha plus ** beta //N//b) range, is an effective means of increasing the corrosion resistance of welded joints in such alloys.