STEEL SHEET COATED WITH Zn-Al-Mg BASED SYSTEM OBTAINED BY IMMERSION INTO MELT HAVING EXCELLENT PROCESSABILITY, AND METHOD FOR PRODUCTION THEREOF Russian patent published in 2019 - IPC C22C38/14 C21D9/46 C23C2/06 

FIELD: metallurgy.

SUBSTANCE: invention relates to production of high-strength steel sheet with coating from system based on Zn-Al-Mg, obtained by immersion into melt, used in automotive industry. Sheet steel contains, wt. %: C: 0.005 to 0.08, Si: 0.8 or less, Mn: from 0.1 to 1.8, P: 0.05 or less, S: 0.02 or less, N: from 0.001 to 0.005, Ti: from 0.02 to 0.2, B: from 0.0005 to 0.01 and Al: 0.1 or less, balance - Fe and unavoidable impurities. Ratio of components Ti/C, defined as (Ti/48)/(C/12), ranges from 0.4 to 1.5. Main phase of sheet is one phase of bainitic ferrite or phase containing phase of bainitic ferrite and phase of ferrite, ratio of area of solid second phase, which is bainite and perlite, and cementite is 3 % or less, and Ti-containing carbides with average particle size of 20 nm or less are dispersed and recovered. Ratio of the small-angle boundaries to the difference in crystal orientation from 2 to 15° ranges from 30 to 75 %.

EFFECT: sheet has tensile strength of 400 MPa or more, high expandability of the hole and high corrosion resistance.

6 cl, 4 dwg, 2 tbl