BLACK SURFACE COATED HIGH STRENGTH MOLTEN Zn-Al-Mg-BASED PLATED STEEL SHEET FOR BUILDING COMPONENT EXCELLENT IN FLEXURE PROCESSABILITY AND BUILDING COMPONENT USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a black surface coated high strength molten Zn-Al-Mg-based plated steel sheet for building component having tensile strength of 780 MPa or more, suppressed manufacturing cost, improved strength and flexure processability, and rich in corrosion resistance, and a building component using the same.;SOLUTION: There are provided a black surface coated high strength molten Zn-Al-Mg-based plated steel sheet for building component, having a molten Zn-Al-Mg-based plated layer on a surface of a raw material steel sheet with a prescribed chemical composition, and having brightness of a surface L* of 60 or less and excellent in flexure processability with tensile strength of 780 to 1100 MPa, in which a single phase of a bainitic ferrite phase or a ferrite phase with dislocation density of 1.8 to 5.7×10¹⁴/m² or a phase containing both phases is a main phase, area percentage of a hard second phase and cementite is 3% or less, carbide containing Ti with average particle diameter of 20 nm or less is dispersed and deposited and black oxide of Zn is dispersed in a molten Zn-Al-Mg-based coating layer having a specific composition at diffusible hydrogen concentration of 0.30 ppm or less, and a building component using the same.;SELECTED DRAWING: Figure 1;COPYRIGHT: (C)2018,JPO&INPIT