C+n austenitic stainless steel having good low-temperature toughness and a fabrication method thereof

Abstract

A C+N austenitic stainless steel includes 15 to 20% by weight of chromium (Cr), 8 to 12% by weight of manganese (Mn), 3% or less by weight of nickel (Ni), and 0.5 to 1.0% by weight of a total content (C+N) of carbon (C) and nitrogen (N), remainder iron (Fe), and other inevitable impurities. A ratio (C/N) of the carbon (C) to the nitrogen (N) ranges from 0.5 to 1.5. It is possible to provide austenitic stainless steel having excellent low-temperature toughness while satisfying the requirements of strength, ductility, and pitting corrosion resistance and minimizing the nickel content

What is claimed is: 
     
         1 . A C+N austenitic stainless steel comprising:
 15 to 20% by weight of chromium (Cr);   8 to 12% by weight of manganese (Mn);   3% or less by weight of nickel (Ni); and   0.5 to 1.0% by weight of a total content (C+N) of carbon (C) and nitrogen (N);   remainder iron (Fe); and   other inevitable impurities,   wherein a ratio (C/N) of the carbon (C) to the nitrogen (N) ranges from 0.5 to 1.5.   
     
     
         2 . The C+N austenitic stainless steel of  claim 1 , wherein the ratio (C/N) of the carbon (C) to the nitrogen (N) ranges from 0.5 to 1.0. 
     
     
         3 . A fabrication method of C+N austenitic stainless steel, comprising:
 a master alloy charging step of charging a master alloy into a vacuum melting furnace;   a vacuum maintaining step of maintaining a vacuum state of the vacuum melting furnace into which the master alloy is charged;   a master alloy melting step of melting the master alloy by heating the vacuum melting furnace;   a nitrogen content adjusting step of injecting a nitrogen gas into the vacuum melting furnace;   a molten ally stirring step of stirring the molten master alloy;   an ingot forming step of forming an ingot by tapping the molten alloy stirred in the vacuum melting furnace;   a hot rolling step of hot-rolling the formed ingot; and   a cooling step of cooling the hot-rolled stainless steel,   wherein the C+N austenitic stainless steel includes 15 to 20% by weight of chromium (Cr); 8 to 12% by weight of manganese (Mn); 3% or less by weight of nickel (Ni); and 0.5 to 1.0% by weight of a total content (C+N) of carbon (C) and nitrogen (N); remainder iron (Fe); and other inevitable impurities, and a ratio (C/N) of the carbon (C) to the nitrogen (N) ranges from 0.5 to 1.5.   
     
     
         4 . The fabrication method of  claim 3 , wherein the ratio (C/N) of the carbon (C) to the nitrogen (N) ranges from 0.5 to 1.0.