METHOD OF MANUFACTURING ALLOYED HOT DIP ZINC PLATED STEEL SHEET HAVING EXCELLENT MOLDABILITY IN PRESSING WORK AND RESISTANCE TO POWDERING

摘要

This invention intends to provide a method of manufacturing an alloyed hot dip zinc plated steel sheet excellent in resistance-to-powdering required for press molding and stable in frictional charateristic in coil. For attaining the object, in this invention, a steel sheet is manufactured through the process that alloying reaction is controlled by plating at a high temperature of the fed-in steel sheet defined in relation to an Al concentration in a bath containing the Al at low concentration, and then alloying treatment is applied thereto in a high frequency induction heating type alloying furnace so that a temperature of the steel sheet may be 495 to 520 DEG C at the outlet side and thus the main phase of said sheet may be delta 1. For higher adaptability of the steel sheet to painting, when required, upper layer plating containing a specified quantity of Fe is applied to the upper layer of said sheet.