METHOD FOR CONTROLLING DEGREE OF ALLOYING OF HOT DIP GALVANIZED STEEL SHEET

摘要

PURPOSE:To obtain a stable degree of alloying accurately by calculating an estimated value for a degree of alloying from a steel sheet to be hot dip galvanized and the relation between operational conditions and a degree of alloying and by deciding conditions during heat treatment so as to attain the estimated value. CONSTITUTION:A weighted time integral value related to a degree of alloying affected by the rate of progress of Fe-Zn diffusion reaction corresponding to a heating temp. is calculated. An alloying inhibiting component such as Al in a zinc layer formed by hot dip galvanizing is identified. An estimated value for a degree of alloying is calculated from the integral value and the effect of Al or the like. Heating conditions during the alloying heat treatment of a hot dip galvanized steel sheet are controlled according to the estimated value.