Abstract: An austenitic stainless steel having excellent processability and surface characteristics and a method of manufacturing the austenitic stainless steel are disclosed. The austenitic stainless steel includes, by weight %, 0.005% to 0.15% of carbon (C), 0.1% to 1.0% of silicon (Si), 0.1% to 2.0% of manganese (Mn), 6.0% to 10.5% of nickel (Ni), 16% to 20% of chromium (Cr), 0.005% to 0.2% of nitrogen (N), the remainder iron (Fe) and other unavoidable impurities, wherein a degree of Ni surface negative segregation defined by the following Formula (1) is in a range of 0.6 to 0.9. (CNi-Min)/(CNi-Ave)??Formula (1), where CNi-Min is a minimum concentration of Ni on the surface of the austenitic stainless steel and CNi-Ave is an average concentration of Ni on the surface of the austenitic stainless steel.

Abstract: An austenitic stainless steel having excellent processability and surface characteristics and a method method of manufacturing the austenitic stainless steel are disclosed. The austenitic stainless steel includes, by weight %, 0.005% to 0.15% of carbon (C), 0.1% to 1.0% of silicon (Si), 0.1% to 2.0% of manganese (Mn), 6.0% to 10.5% of nickel (Ni), 16% to 20% of chromium (Cr), 0.005% to 0.2% of nitrogen (N), the remainder iron (Fe) and other unavoidable impurities, wherein a degree of Ni surface negative segregation defined by the following Formula (1) is in a range of 0.6 to 0.9. (CNi-Min)/(CNi-Ave)??Formula (1), where CNi-Min is a minimum concentration of Ni on the surface of the austenitic stainless steel and CNi-Ave is an average concentration of Ni on the surface of the austenitic stainless steel.

Abstract: The object of the present invention is to provide stainless steel for high vacuum and high purity gas tube applications not having intrusion of impure particles into a processing gas and being cost-efficient. In order to accomplish the object, the present invention provides an austenitic stainless steel for a high vacuum and high purity gas tube application, the stainless steel including, in percent by weight, 0.1% or less of C, 1% or less of Si, 0.5 to 2% of Mn, 0.05% or less of P, 0.01% or less of S, 15 to 30% of Cr, 7 to 20% of Ni, 4% or less of Mo, 3% or less of Cu, 0.05% or less of N, 0.01% or less of B, 0.01% or less of O, a remaining part of Fe, and unavoidable impurities, wherein Ti content is limited to 0.005% or less, Al content is limited to 0.005 to 0.05%, and Ca content is limited to 0.0005 to 0.003%.

Abstract: Disclosed is duplex stainless steel that containes relatively low content of Ni, and limits constituents of Cr—Mo—Mn—N to make volume fraction of ? and ? have about 50:50, thereby minimizing incidence of a edge crack to enhance a production yield and decrease a processing load, in which the alloy constituents includes Cr of 19.5˜22.5%. Mo of 0.5-2.5%, Ni if 1.0-3.0%, Mn of 1.5-4.5%, N of 0.15-0.25%, Fe and unavoidable elements, and a constitution range of the alloy constituents are adjusted to make a CPt higher than 20° C. depending on the constitution range of the alloy constituents. Thus, the contents of Cr, Mo and Ni is decreased and the content of Mn is increased a little, so that a production cost thereof is reduced; the corrosion resistance is secured to be better than the STS 304 steel and the 316L steel; the incidence of the edge cract is decreased while being hot-rolled, thereby decreasing a load on the following process; and the surface defective is decreased, thereby improving a production yield.

Abstract: A duplex stainless steel consisting of a ferrite phase and an austenite phase is disclosed which is superior in the hot ductility, the high temperature oxidation resistance, the corrosion resistance and the impact toughness. The duplex stainless steel is applied to marine facility and the like. The duplex stainless steel which consists of a ferrite phase and an austenite phase is composed of in weight %: less than 0.03% of C, less than 1.0% of Si, less than 2.0% of Mn, less than 0.04% of P, less than 0.004% of S, less than 2.0% of Cu, 5.0-8.0% of Ni, 22-27% of Cr, 1.0-2.0% of Mo, 2.0-5.0% of W, and 0.13-0.30% of N. Or there are further added one or two elements selected from a group consisting of: less than 0.03% of Ca, less than 0.1% of Ce, less than 0.005% of B and 0.5% of Ti. Further, the ratio (Cr.sub.eq /Ni.sub.eq) of the Cr equivalent (Cr.sub.eq) to the Ni equivalent (Ni.sub.eq) is 2.2-3.0. Further, the weight ratio (W/Mo) of the W to Mo is 2.6-3.4.