HOT-DIP GALVANIZED STEEL SHEET AND METHOD FOR PRODUCING SAME

• Main Authors: KARIYA, Nobusuke, TAKASHIMA, Katsutoshi, TOJI, Yuki, HASEGAWA, Kohei
• Format: Patent
• Language: English; French; German
• Published: 04.11.2020
• Subjects: ALLOYS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; LAYERED PRODUCTS; LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

Provided is a high-strength hot-dip galvanized steel sheet having excellent workability, namely, excellent ductility and hole expansion formability, and high yield ratio. The steel sheet has a chemical composition containing by mass %: C: 0.05-0.15 %; Si: 0.10-0.90 %; Mn: 1.0-1.9 %; P: 0.005-0.10 %; S: 0.0050 % or less; Al: 0.01-0.10 %; N: 0.0050 % or less; Nb: 0.010-0.100 %; and the balance being Fe and incidental impurities, in which: the steel sheet has a complex phase that includes: ferrite having an average crystal grain size of 15 µm or less to at least 90 % in volume fraction; martensite having an average crystal grain size of 3.0 µm or less to 0.5 % or more and less than 5.0 % in volume fraction; pearlite to 5.0 % or less in volume fraction; and the balance being a phase generated at low temperature.