Posco

Posco Co., Ltd

Soon-Gi Lee

In-Gyu Park

In-Shik Suh

Hong-Ju Lee

Yong-Jin Kim

Sang-Deok Kang

Sung-Kyu Kim

Jong-Kyo Choi

Un-Hae Lee

Hee-Goon Noh

Hak-Cheol Lee

Il-Cheol Yi

Hong-Yeol Oh

Young-Hwan Park

Hyun-Kwan Cho

Provided according to one embodiment of the present invention are a non-magnetic steel material and a method for manufacturing the same. The steel material comprises 15-27 wt % of manganese, 0.1-1.1 wt % of carbon, 0.05-0.50 wt % of silicon, 0.03 wt % or less (0% exclusive) of phosphorus, 0.01 wt % or less (0% exclusive) of sulfur, 0.050 wt % or less (0% exclusive) of aluminum, 5 wt % or less (0% inclusive) of chromium, 0.01 wt % or less (0% inclusive) of boron, 0.1 wt % or less (0% exclusive) of nitrogen, and a balance amount of Fe and inevitable impurities, has an index of sensitivity of 3.4 or less, the index of sensitivity being represented by the following relational expression (1): [Relational expression 1]−0.451+34.131*P+111.152*Al−799.483*B+0.526*Cr≤3.4 (wherein [P], [Al], [B] and [Cr] each mean a wt % of corresponding elements), and contains a microstructure with austenite at an area fraction of 95% or greater therein.

Austenitic steel material having excellent hot workability and manufacturing method therefor

Provided according to one embodiment of the present invention are a non-magnetic steel material and a method for manufacturing the same. The steel material comprises 15-27 wt % of manganese, 0.1-1.1 wt % of carbon, 0.05-0.50 wt % of silicon, 0.03 wt % or less (0% exclusive) of phosphorus, 0.01 wt % or less (0% exclusive) of sulfur, 0.050 wt % or less (0% exclusive) of aluminum, 5 wt % or less (0% inclusive) of chromium, 0.01 wt % or less (0% inclusive) of boron, 0.1 wt % or less (0% exclusive) of nitrogen, and a balance amount of Fe and inevitable impurities, has an index of sensitivity of 3.4 or less, the index of sensitivity being represented by the following relational expression (1): [Relational expression 1]&#x2014;0.451+34.131*P+111.152*Al&#x2212;799.483*B+0.526*Cr&#x2264;3.4 (wherein [P], [Al], [B] and [Cr] each mean a wt % of corresponding elements), and contains a microstructure with austenite at an area fraction of 95% or greater therein.

Non-magnetic steel material having excellent hot workability and manufacturing method therefor

Provided are an austenitic steel having excellent machinability and ultra-low temperature toughness in a weld heat-affected zone including 15 wt % to 35 wt % of manganese (Mn), carbon (C) satisfying 23.6C+Mn&#x2265;28 and 33.5C&#x2212;Mn&#x2264;23, 5 wt % or less (excluding 0 wt %) of copper (Cu), chromium (Cr) satisfying 28.5C+4.4Cr&#x2264;57 (excluding 0 wt %), and iron (Fe) as well as other unavoidable impurities as a remainder, wherein a Charpy impact value of a weld heat-affected zone at &#x2212;196&#xb0; C. is 41 J or more, and a method of manufacturing the steel. According to the present invention, a low-cost ultra-low temperature steel may be obtained, a stable austenite phase may be formed at low temperature, carbide formation may be effectively suppressed, and a structural steel having excellent machinability and ultra-low temperature toughness in a weld heat-affected zone may be provided.

Austenitic steel having excellent machinability and ultra-low temperature toughness in weld heat-affected zone, and method of manufacturing the same

The present invention relates to a high strength austenitic-based steel with remarkable toughness of a welding heat-affected zone and a preparation method therefor. One embodiment of the present invention provides: a high strength austenitic-based steel with remarkable toughness of a welding heat-affected zone, comprising 0.8-1.5 wt % of C, 15-22 wt % of Mn, 5 wt % or less of Cr (except 0), and the balance of Fe and other inevitable impurities, and further comprising at least one of the following (a) and (b), wherein the microstructure of a welding heat-affected zone comprises 90% or more of austenite by volume fraction; and a preparation method therefor. (a) Mo: 0.1-1% and B: 0.001-0.02% (b) Ti: 0.01-0.3% and N: 0.003-0.1%.

High strength austenitic-based steel with remarkable toughness of welding heat-affected zone and preparation method therefor

A high-manganese wear-resistant steel having excellent weldability comprises 5 to 15 wt % of Mn, 16&#x2264;33.5C+Mn&#x2264;30 of C, 0.05 to 1.0 wt % of Si, and a balance of Fe and other inevitable impurities. The microstructure thereof includes martensite as a major component, and 5% to 40% of residual austenite by area fraction.

High-manganese wear resistant steel having excellent weldability and method for manufacturing same

There are provided a wear resistant austenitic steel having superior machinability and toughness in weld heat affected zones and a method for producing the austenitic steel. The austenitic steel includes, by weight %, manganese (Mn): 15% to 25%, carbon (C): 0.8% to 1.8%, copper (Cu) satisfying 0.7C-0.56(%)&#x2266;Cu&#x2266;5%, and the balance of iron (Fe) and inevitable impurities, wherein the weld heat affected zones have a Charpy impact value of 100 J or greater at &#x2212;40&#xb0; C. The toughness of the austenitic steel is not decreased in weld heat affected zones because the formation of carbides during welding is suppressed, and the machinability of the austenitic steel is improved so that a cutting process may be easily performed on the austenitic steel. The corrosion resistance of the austenitic steel is improved so that the austenitic steel may be used for an extended period of time in corrosive environments.

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Pohang-si, South Korea

Soon-Gi Lee