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US 12,624,411 B2Granted
High-strength steel sheet having excellent formability and method for manufacturing thereof
AssigneePosco
InventorsSung-Kyu Kim, Jun-Ho Park, Chang-Hyo Seo, Eul-Yong Choi, Sang-Ho Han
Life of this patent
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Abstract
Provided is a high-strength steel sheet suitable for automobile structural members, etc., and a method for manufacturing same, wherein the high-strength steel sheet has a low yield ratio and high strength and has excellent formability through improvement of ductility that may prevent processing defects such as cracks, wrinkles, or the like, during press forming.
Claims4
A steel sheet comprising, by weight %:
- 0.05 to 0.15% of carbon (C), 0.5% or less (excluding 0%) of silicon (Si), 2.0 to 3.0% of manganese (Mn), 0.2% or less (excluding 0%) of titanium (Ti), 0.1% or less (excluding 0%) of niobium (Nb), 0.2% or less (excluding 0%) of vanadium (V), 0.5% or less (excluding 0%) of molybdenum (Mo), 0.1% or less of phosphorus (P), 0.01% or less of sulfur (S), and a remainder of Fe and unavoidable impurities,
- wherein a microstructure is composed of ferrite with an area fraction of 20 to 45%, and a remainder of martensite and bainite, and
- a fraction of non-recrystallized ferrite, among the ferrite is 25 area % or less, and an average aspect ratio thereof (major axis:minor axis) is 1.1 to 2:1.
Dependencies are inferred from the claim text.