Total of possession area ratio of the debris which exists

摘要

PROBLEM TO BE SOLVED: To provide an electric resistance welded tube containing Cr having considerably excellent quality of an electric resistance welded part as compared with conventional quality, and a manufacturing method thereof.;SOLUTION: The total occupied area ratio of inclusions present in a joining interface after the electric resistance welding of an electric resistance welded steel tube containing Cr is ≤0.05%, the occupied area of individual inclusions is ≤0.01 mm², and the number density of the inclusions in the electric resistance welded steel tube containing Cr is ≤0.1 piece/mm². This steel tube can be manufactured by spraying reducing high-temperature combustion flame or reducing plasma at the temperature of ≥1,400°C in a vicinity of a welding point during the electric resistance welding.;COPYRIGHT: (C)2005,JPO&NCIPI