HIGH TENSILE STRENGTH HOT DIP PLATED STEEL SHEET AND METHOD FOR PRODUCTION THEREOF

摘要

A method for producing a high tensile strength hot dip plated steel sheet, which comprises providing a steel sheet having a Si content controlled within a specific range and comprising Nb and one or more of Cu, Ni and Mo, subjecting a rolled sheet to a recrystallization annealing to thereby form an inner oxide layer close under the surface of the steel plate, washing the surface with an acid to remove the oxides having been formed also on the surface, heating the resultant steel sheet prior to plating, and then subjecting the sheet to a hot dip plating. The inner oxide layer formed during annealing acts as a barrier against diffusion of Si, Mn and the like during the heat treatment prior to plating, which results in marked reduction of the formation of oxides of Si, Mn and the like. Accordingly, the method can be used for producing a high tensile strength hot dip plated steel sheet which exhibits markedly excellent plating characteristics.