HIGH STRENGTH GALVANIZED STEEL PLATE AND HIGH-STRENGTH ALLOY DIP GALVANIZED STEEL SHEET HAVING EXCELLENT COATING ADHESION, FORMABILITY AND HOLE EXPANSION, WITH A TENSILE STRENGTH OF 980 MPA OR MORE, AND A METHOD OF ITS PRODUCTION

摘要

FIELD: steel industry.;SUBSTANCE: invention relates to a galvanized steel sheet. High-strength galvanized steel sheet includes a plating layer formed on the surface of the base steel sheet. Main steel sheet comprises, in weight.%: C 0.05 to 0.4; Si: 0.01 to 3.0; Mn: 0.1 to 3.0; Al of 0.01 to 2.0, wherein Al + Si 0.5, P - 0.04 or less, S - 0.05 or less N - 0.01 or less, iron and inevitable impurities - the rest. Microstructure of the steel sheet contains 40 % or more in the total volume fraction of martensite and bainite, 8 % or more, the volume fraction of retained austenite, and the balance - ferrite or ferrite to 10 % or less of the volume fraction of pearlite, wherein the martensite contains 10 % or more, total volume fraction of two or more of three types of martensite, and the plating layer contains less than 7 wt.% iron.;EFFECT: technical result is to obtain a galvanized sheet having excellent coating adhesion, formability, hole expansion with a maximum tensile strength of 980 MPa or more.;16 cl, 4 tbl