HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET AND METHOD FOR MANUFACTURING SAME

• Main Authors: OZAWA Yuichi, UTAKA Minoru, TARIGAN Imanuel, KIZU Taro
• Format: Patent
• Language: English; French; German
• Published: 12.12.2018
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

A high-strength hot-dip galvanized steel sheet and a method for producing the high-strength hot-dip galvanized steel sheet are provided. The steel sheet has a composition including, on a mass percent basis, C: 0.05% to 0.15%, Si: 0.1% or less, Mn: 1.0% to 2.0%, P: 0.10% or less, S: 0.030% or less, Al: 0.10% or less, and N: 0.010% or less, and including one or two or more of Ti, Nb, and V satisfying the formula (1), the remainder being iron and incidental impurities. The steel sheet has a microstructure containing, on an area percent basis, ferrite: 80% or more, and bainite and martensite: 1% to 20% in total. The ferrite has an average grain size of 10.0 µm or less, and a phase containing bainite and martensite has an average grain size of 3.0 µm or less. The ratio of the average grain size of the phase containing bainite and martensite to the average grain size of the ferrite is 0.3 or less. 0.008 % ‰¤ 12 × Ti / 48 + Nb / 93 + V / 51 ‰¤ 0.05 % Ti, Nb, and V denote their respective contents (% by mass). In the absence of Ti, Nb, or V, the corresponding content is 0.