MANUFACTURING METHOD OF HOT DIP Zn-Al-Mg ALLOY PLATED STEEL PLATE HAVING EXCELLENT PLATING ADHESION

摘要

PROBLEM TO BE SOLVED: To provide a manufacturing method of a hot dip Zn-Al-Mg alloy plated steel plate having an excellent plating adhesion by using a steel plate as a plating substrate, the steel plate being imparted by a hot dip metal embrittlement crack resistance by adding B to a relatively high-Mn-based high-strength steel.;SOLUTION: When a maximum arrival temperature of a steel plate surface is defined as "a reduction heat treatment temperature" inside a furnace of a reduction heat treatment performed in a case where a steel plate is introduced to a hot dip Zn-Al-Mg alloy plating bath, the reduction heat treatment is performed to secure a plating adhesion by suppressing coverage of the steel plate surface with BN in the reduction heat treatment, the reduction heat treatment being performed at a dew point within an area (including a boundary) enclosed by lines connecting points of A(-75,800)-B(-45,900)-C(-10,900)-D(-10,750)-E(-75,750)-A in an orthogonal coordinate system of a real number scale where an x-axis is a dew point within the furnace and a y-axis is the reduction heat treatment temperature (°C) and under a condition satisfying the reduction heat treatment temperature.;SELECTED DRAWING: Figure 2;COPYRIGHT: (C)2017,JPO&INPIT