Abstract: The present invention minimizes the addition of alloying elements to reduce surface cracking during hot rolling, ensures corrosion resistance by constituting Cr as one of the main components, and realizes a TRIP or TWIP phenomenon through a high Mn design, thereby providing a low alloy steel sheet with excellent hot workability, strength and ductility. The low alloy steel sheet excellent in strength and ductility according to an embodiment of the present invention comprises, in percent (%) by weight of the entire composition, 0.05 to 0.3% of carbon (C), 0.7 to 2.5% of silicon (Si), 8 to 12% of manganese (Mn), 13 to 15.5% of chromium (Cr), 0.5 to 3.0% of copper (Cu), 0.1 to 0.2% of nitrogen (N), 0.25% or less of aluminum (Al), 0.25% or less of tin (Sn), and the remainder of iron (Fe) and other inevitable impurities. The microstructure of the low alloy steel sheet comprises at least one of a ferrite phase and a martensite phase at a volume fraction of 5% or less, and the remainder includes an austenite phase.

Abstract: A lean duplex stainless steel and a method of manufacturing the same are provided. The lean duplex stainless steel includes, in percent (%) by weight of the entire composition, 0.08% or less of carbon (C) (excluding 0), 0.7 to 1.1% of silicon (Si), 2.4 to 3.5% of manganese (Mn), 17.9 to 20.7% of chromium (Cr), 0.05 to 1.15% of nickel (Ni), 0.18 to 0.3% of nitrogen (N), 0.4 to 2.8% of copper (Cu), and the remainder of iron (Fe) and inevitable impurities, wherein a predicted pitting potential is from 360 to 440 mV. Thus, manufacturing costs may be reduced via adjustment of components of the duplex stainless steel and both of formability and corrosion resistance may be improved by improving corrosion resistance and increasing elongation. Formability may be improved by inhibiting formation of thermal martensite and increasing elongation via adjustment of cooling conditions during coiling and cooling after hot rolling.

Abstract: Disclosed is an austenitic stainless steel with increased workability. The austenitic stainless steel includes, based on % by weight, silicon (Si): 0.1 to 0.65%, manganese (Mn): 0.2 to 3.0%, nickel (Ni): 6.5 to 10.0%, chromium (Cr): 16.5 to 20.0%, copper (Cu): 6.0% or less (excluding 0), the sum of carbon (C) and nitrogen (N): 0.08% or less (excluding 0), and the remainder being Fe and unavoidable impurities, wherein the austenitic stainless steel has a work hardening rate of 1500 MPa or less within a true strain range of 0.15 to 0.4. Therefore, when a sink bowl and the like are processed using the austenitic stainless steel, the true strain and work hardening rate of which are controlled, the occurrence of delayed fracture in a molded corner thereof, which has been subjected to a large amount of processing, can be prevented.

Abstract: Provided are lean duplex stainless steel in which delayed fracture does not occur and thus a drawing property is improved, and a method for producing the lean duplex stainless steel. The lean duplex stainless steel having a superb drawing property according to the present disclosure includes, in weight %, C: 0.02% to 0.08%, Si: 0.5% to 1.3%, Mn: 2.5% to 3.5%, Cr: 19% to 21%, Ni: 0.6% to 1.2%, N: 0.2% to 0.3%, Cu: 0.5% to 1.2%, and the remainder of Fe and other inevitable impurities, and, as annealed dual-phase steel of ferrite and austenite, Md_SIM10 corresponding to a temperature measured when an amount of strain-induced martensite formed after 0.3 true strain reaches 10%, and a limit drawing ratio (LDR) satisfy the expressions below. ?30° C.Md_SIM10?0° C. - - - (expression 1) and 2.08?LDR?2.

Abstract: Provided are lean duplex stainless steel having a dual-phase structure of an austenite phase and a ferrite phase, and a method for producing the lean duplex stainless steel. The lean duplex stainless steel, as a ferrite-austenite stainless steel, has the preferred stacking fault energy (SFE) value of the austenite phase, expressed by the formula 2 below, of 19-37 and critical strain value range, within which the strain-induced martensite phases occurs, of 0.1?0.25. Formula 2: SFE=25.7+1.59×Ni/[K(Ni)?K(Ni)×V(?)+V(?)]+0.795×Cu/[K(Cu)?K(Cu)×V(?)+V(?)]?0.85×Cr/[K(Cr)?K(Cr)×V(?)+V(?)]+0.001×(Cr/[K(Cr)?K(Cr)×V(?)+V(?)])2+38.2×(N/[K(N)?K(N)×V(?)+V(?)])0.5?2.8×Si/[K(Si)?K(Si)×V(?)+V(?)]?1.34×Mn/[K(Mn)?K(Mn)×V(?)+V(?)]+0.06×(Mn/[K(Mn)?K(Mn)×V(?)+V(?)])2. Ni, Cu, Cr, N, Si and Mn indicate the overall content (wt.