RESISTANCE WELDED TUBE EXCELLENT IN CORROSION RESISTANCE TO CARBON DIOXIDE GAS AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To produce a resistance welded tube free from selective corrosion in a weld zone under a corrosive environment of carbon dioxide gas. ;SOLUTION: This tube is a resistance welded tube which has a composition containing, as essential components, ≤0.2%, by weight, C, ≤0.5% Si, ≤2% Mn, ≤0.07% Al, 0.2-3% Cr, and ≤0.01% N and having the balance essentially Fe and also has a melted and solidified structure in a resistance welded zone. Further, the resistance welded tube manufacturing process has a stage for preparing a steel sheet with the composition, a stage for forming the steel sheet into an open pipe, a stage for heating both edges, facing each other, of the open pipe up to a temp. not higher than the melting temp. of the steel, and a stage for melting both edges of the open pipe by means of laser irradiation and also performing upset welding. This resistance welded tube has excellent corrosion resistance to wet carbon dioxide gas corrosion in a resistance welded zone as well as in a base material.;COPYRIGHT: (C)1997,JPO