Postech Academy-industry Foundation

Posco

Seok-su Sohn

Sung-hak Lee

Kyoo-Young Lee

Joo-Hyun Ryu

Sea-Woong Lee

Byeong-joo Lee

Dong-geun Kim

Hyoung-seop Kim

Won-mi Choi

Hyung-Soo Lee

Yong-hee Jo

Min-Chul Jo

Hyoung-Seop Kim

Byeong-Joo Lee

Won-Mi Choi

Dong-Geun Kim

Sung-Hak Lee

Present invention is about a transformation-induced plasticity high-entropy alloy which can provide improved mechanical properties compared to those obtained by conventional methods, due to the phase transformation occurring at the time of deformation at a cryogenic temperature. According to the present invention, the high-entropy alloy (HEA) includes 10-35 at % of Co, 3-15 at % of Cr, 3-15 at % of V, 35-48 at % of Fe, and 0-25 at % of Ni (exclusive of 25), and mainly consists of an FCC phase at room temperature, wherein transformation-induced plasticity, in which at least part of the FCC phase changes to a BCC phase, occurs at a cryogenic temperature (&#x2212;196&#xb0; C.)

Transformation-induced plasticity high-entropy alloy and preparation method thereof

Provided is a hot rolled steel sheet having excellent strength and elongation. The hot rolled steel sheet contains, by wt %: carbon (C): 0.05% or more and less than 0.4%, manganese (Mn): 10% to 15%, aluminum (Al): 2% or less, silicon (Si): 0.1 to 2%, molybdenum (Mo): 0.5% or less (excluding 0), vanadium (V): 0.5% or less (excluding 0), phosphorus (P): 0.01% or less, sulfur (S): 0.01% or less, and a remainder of iron (Fe) and inevitable impurities. The hot rolled steel sheet has a microstructure of the hot rolled steel sheet containing, by area %, tempered martensite: 50% to 70%, secondary martensite: 20% or less (excluding 0), epsilon martensite: 2% or less (excluding 0), and retained austenite: 8% to 30%. The hot rolled steel sheet has a tensile strength of at least 1500 MPa, a yield strength of at least 900 MPa and elongation of at least 20%.

Hot rolled steel sheet having excellent strength and elongation

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Ulsan, South Korea

Seok-su Sohn