Features of the Phase Transformations in Sheets, Tubes and Welding Seams of the Alloy Zr–2.5%Nb

By use of X-ray texture analysis characteristic features of phase transformations in sheets,tubes and welding seams of the Zr–2.5%Nb alloy were studied. Main attention was givento inhomogeneity of phase transformation development, connected with inhomogeneousdistribution of strain hardening in grains with different crystallographic orientations. Thetypical manifestation of phase transformation inhomogeneity in cold-rolled sheets is ashift of the initial texture maximum to the region of increased strain hardening. Inchannel tubes in consequence of phase transformations α − β − α the texture component { 11 2 − 0 } 〈 10 1 − 0 〉 gains, testifying that tangential stresses favour corresponding alignment ofbasal normals accompanied by absorption of grains with other orientations. Competitionbetween recrystallization and phase transformation in conditions of heating was considered.As strain hardening increases, recrystallization prior to phase transformationbecomes more probable, being predominant within α -grains of some orientations. Paralleldevelopment of recrystallization and phase transformation in the zone of thermalinfluence by arc welding of rolled sheets was considered. It was shown that, as the distancefrom the melting zone decreases, different combinations of these processes realize.