ULTRA-HIGH STRENGTH COLD-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREFOR

Organization Name

Inventor(s)

ULTRA-HIGH STRENGTH COLD-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREFOR

This abstract first appeared for US patent application 18961422 titled 'ULTRA-HIGH STRENGTH COLD-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREFOR

Original Abstract Submitted

Provided is an ultra-high strength cold-rolled steel sheet, including: carbon (C): 0.23% to 0.40%; silicon (Si): 0.05% to 1.0%; manganese (Mn): 0.5% to 3.0%; vanadium (V): 0.01% to 0.12%; aluminum (Al): 0.01% to 0.3%; chromium (Cr): greater than 0% and 0.5% or less; titanium (Ti): greater than 0% and 0.1% or less; phosphorus (P): greater than 0% and 0.02% or less; sulfur(S): greater than 0% and 0.01% or less; and boron (B): 0.001% to 0.005%, based on % by weight; and a remainder being Fe and other unavoidable impurities, wherein a final microstructure includes tempered martensite having a volume fraction of 90% or more, wherein an average spacing between precipitates in the tempered martensite is 300 nm or more, an average size of the precipitates is 200 nm or less, and the number of precipitates having an average size of 40 nm or less is 25 or more based on an area of 20 μmin the final microstructure.