PURPOSE: To improve heat transfer efficiency by reducing the thickness and the weight of a tube and reduce wearing due to oxidization under a high temperature by a method wherein the uniformly thick coating layer of a high- temperature resistant oxidizing alloy is provided on the inner surface of a heat resistant metallic tube, produced through hot extrusion work, or on both of the inner and outer surfaces of the same tube.
CONSTITUTION: A capsule, consisting of a thick outer tube 1, produced by hot extrusion work and made of a heat resistant metal, a thin inner tube 2, made of a proper mareable material, and a forged bottom 3, made of the same mareable material, is produced. A space between the inner and outer tubes is filled with the powder 4 of a high-temperature resistant oxidizing alloy such as Ni-Cr-Al series or Co-Cr-Al and a lid 5 consisting of a mareable material is welded to seal the capsule whereby a billet is produced. The billet thus obtained is processed through deaeration, normal-temperature isotropic pressure compression, preheating and the like if necessary and, thereafter, is heated to an extrusion working temperature through induction heating and is loaded into a hot extruding machine to extrude it into a tubular body, then, the layer of capsule material is removed whereby a product may be obtained.
ABE GENRYU
MATSUDA SADAMU
ADACHI MASAHIRO
NIPPON WELDING ROCK KK
| JPS556679B2 | 1980-02-19 |