Cantor Colburn LLP
Ultra-high strength steel plate having excellent formability and hole-expandability, and method for manufacturing same
Provided is an ultra-high strength steel plate for automobiles and, more specifically, to an ultra-high strength steel plate having high formability and hole expandability, and a method for manufacturing the ultra-high strength steel plate. The ultra-high strength steel plate includes: by wt %, carbon (C): 0.04% to 0.17%, silicon (Si): 2% or less, manganese (Mn): 4% to 10%, phosphorous (P): 0.05% or less (excluding 0%), sulfur (S): 0.02% or less (excluding 0%), aluminum (Al): 0.5% or less (excluding 0%), nitrogen (N): 0.02% or less (excluding 0%), and a balance of iron (Fe) and inevitable impurities. Carbon (C) and manganese (Mn) satisfy Formula C+(Mn/25)≤0.46. The ultra high strength steel plate has a microstructure comprising retained austenite in a volume fraction of 20% or greater and annealed martensite in a volume fraction of 50% or greater.
POSCO
C C C C C C C C C C C C C C C C C C C C C B
C22C C21D C22C C22C C21D C23C C22C C21D C21D C21D C21D C21D C21D C23C C23C C23C C22C C22C C22C C21D C21D B32B
inventional inventional inventional inventional inventional inventional inventional additional inventional additional inventional inventional inventional inventional inventional inventional inventional inventional inventional inventional inventional inventional
Kyoo-Young Won-Hwi Byun-Mok Sea-Woong Joo-Hyun
Lee Lee Hwang Lee Ryu