Abstract: A metal tube induction annealing apparatus employs an induction heating enclosure having an elongated glass tube encircled by an electromagnetic coil of an induction heating system which provides an induction annealing chamber for receiving a hollow metal tube for undergoing annealing and an inert purge gas for bathing the tube during annealing. Cooling stages are located end-to-end downstream of the induction enclosure for progressively cooling the annealed tube. The inert purge gas is made to flow upstream in a direction opposite to the downstream direction of tube movement through the annealing chamber and cooling stages for accomplishing constant bathing or shielding of the exterior and interior wall surfaces of the tube and removal of heat by inert purge gas flowing through and out of the trailing end of the tube.

Abstract: Processes for the rapid alpha annealing of zirconium based articles are described. These processes utilize induction heating to rapidly heat a worked zirconium based article to an elevated temperature after which it is then cooled. Time at the selected elevated temperature is less than about 1 second, and preferably essentially zero. Stress relieving of cold pilgered Zircaloy may be performed by induction heating to a temperature between about 540.degree. and about 650.degree. C. Partial recrystallization annealing of cold pilgered Zircaloy may be performed by induction heating to a temperature between about 650.degree. and about 760.degree. C. Full alpha recrystallization annealing of cold pilgered Zircaloy may be performed by induction heating to a temperature between about 760.degree. and about 900.degree. C.

Abstract: A method of more rapidly and uniformly heating bundles of zirconium alloy tubes in a vacuum annealing furnace utilizes an induction coil to preheat the entire bundle as it is being moved into the hot zone of the furnace.