COLD ROLLED STEEL SHEET HAVING EXCELLENT WELDABILITY, STRENGTH, AND FORMABILITY, AND METHOD FOR MANUFACTURING SAME
Abstract:
Provided is a cold-rolled steel sheet including: by weight %, C: 0.10 to 0.16%, Si: 0.3 to 0.8%, Al: 0.01 to 0.5%, Mn: 2.0 to 3.0%, Cr: 0.001 to 0.5%, Mo: 0.001 to 0.5%, B: 0.0001 to 0.001%, Nb: 0.001 to 0.05%, Ti: 0.001 to 0.05%, P: 0.04% or less (excluding 0%), S: 0.01% or less (excluding 0%), N: 0.01% or less (excluding 0%), a remainder of Fe, and other unavoidable impurities, as a microstructure, by area %, ferrite: 10% or less (excluding 0%), retained austenite: more than 1% to 5% or less, martensite: 25% or more but less than 50%, and bainite: 35% or more but less than 70%. An average size of martensite-austenite (MA) in the bainite is 0.35 to 0.55 μm.
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