METHOD FOR CONTROLLING ORIENTATION OF HYDRIDE IN PILGER ROLLING OF ZIRCONIUM ALLOY COATED PIPE

摘要

PURPOSE:To control the deposition direction of hydride in a circumferential direction in Pilger rolling of a zirconium alloy pipe by rolling the pipe under the conditions wherein the working parameter in a working region is specified. CONSTITUTION:A mandrel 4 is inserted into a base pipe 3 which is a zirconium alloy pipe, and while the pipe is rotated at each specified angle, the pipe is fed into the space between dies 1, 2 under revolving at a specified speed, thereby forming continuously a rolled pipe 5 having a decreased pipe diameter and wall thickness. The pipe is rolled under the conditions of the working parameter thetaepsilon in the working region expressed by the equation. In the equation, (t): the wall thickness of the rolled pipe, (d): the average diameter of the rolled pipe, T': the wall thickness of the base pipe in the position where the thick wall working starts in the midway of rolling, D': the average diameter of the base pipe in the position where the thick wall working starts in he midway of the rolling. The plate-like crystal of the zirconium hydride produced by the reaction of zirconium and water is thus precipitated in such a way that the longitudinal direction thereof is in the circumferential direction of the pipe.