PRODUCTION OF HEAT EXCHANGER TUBE MATERIAL MADE OF AL AND AL ALLOY COATED WITH THIN ZINC SPRAY COATING FILM HAVING UNIFORM THICKNESS AND SUPERIOR ADHESION

摘要

PURPOSE: To produce a heat exchanger tube material having a thin coating film of uniform thickness, excellent in adhesion, by subjecting an Al and Al alloy billet to hot extrusion at specific temp. into a tube stock, applying forced cooling to the tube stock down to specific temp., and then forming a thin zinc sprayed coating film thereon. ;CONSTITUTION: An Al and Al alloy billet is formed into a heat exchanger tube stock by means of hot extrusion. At this time, the hot extrusion is finished at ≥450°C, by which a thin-walled tube stock of complicated shape can be produced in high yield. By subjecting the tube stock after working to forced cooling down to a prescribed temp. between 390 and 200°C, the formation of surface oxides is prevented and the flowability of a thin sprayed coating on the surface is reduced and also its adhesion is improved. in this state, a thin coating film is formed on the surface by means of zinc thermal spraying, followed by cooling. By this method, the heat exchanger tube material made of Al and Al alloy, which has a thin zinc sprayed coating film having uniform thickness, minimal in variance, showing superior pitting corrosion resistance, and excellent in adhesion, can be obtained.;COPYRIGHT: (C)1994,JPO&Japio