Production manner null of the melting galvanized steel sheet and the alloy melting galvanized steel sheet which are superior in the melting

摘要

PROBLEM TO BE SOLVED: To perfectly prevent the occurrence of non-coating portion in a galvanizing treatment and also, the development of powdering after galvannealing treatment.;SOLUTION: When a galvanized steel sheet is produced, after hot-rolling under state of sticking the mill scale on the steel sheet, a heat treatment is applied in the temperature range of 650-950°C in the atmosphere, in which the reduction is not substantially developed, an inner oxidized layer is formed on the iron surface layer part of the steel sheet. Further, the atmosphere in a snout for introducing the steel sheet from the heat treatment furnace into a galvanizing bath is regulated to ≤70 vol. ppm oxygen content.;COPYRIGHT: (C)2001,JPO