Ferritic stainless steel having excellent strength and corrosion resistance to acid and method of manufacturing the same

Abstract

Provided are a ferritic stainless steel having an excellent strength and corrosion resistance to acid and a method of manufacturing the same. The ferritic stainless steel according to an embodiment of the present disclosure includes, by weight %, 0.1% to 0.2% of carbon (C), 0.005% to 0.05% of nitrogen (N), 0.01% to 0.5% of manganese (Mn), 12.0% to 19.0% of chrome, 0.01% to 0.5% of nickel (Ni), 0.3% to 1.5% of copper (Cu), the remainder iron (Fe) and other inevitable impurities, wherein a number of carbides having a diameter of 100 nm or more per unit area is 50 ea/100 μm2 to 200 ea/100 μm2.

1 . A ferritic stainless steel having an excellent strength and acid resistance, comprising, by weight %, 0.1% to 0.2% of carbon (C), 0.005% to 0.05% of nitrogen (N), 0.01% to 0.5% of manganese (Mn), 12.0% to 19.0% of chrome (Cr), 0.01% to 0.5% of nickel (Ni), 0.3% to 1.5% of copper (Cu), the remainder iron (Fe) and other inevitable impurities, wherein a number of carbides having a diameter of 100 nm or more per unit area is 50 ea/100 μm 2  to 200 ea/100 μm 2 . 
     
     
         2 . The ferritic stainless steel of  claim 1 , wherein an average crystal grain diameter is 10 μm or less. 
     
     
         3 . The ferritic stainless steel of  claim 1 , wherein a tensile strength is 520 MPa or more. 
     
     
         4 . The ferritic stainless steel of  claim 1 , wherein an elongation is 20% or more. 
     
     
         5 . The ferritic stainless steel of  claim 1 , wherein a critical current density I crit  in a 5% sulfuric acid atmosphere is 10 mA or less. 
     
     
         6 . A method of manufacturing a ferritic stainless steel having an excellent strength and acid resistance, comprising hot-rolling and cold-rolling a ferritic stainless steel slab comprising, by weight %, 0.1% to 0.2% of carbon (C), 0.005% to 0.05% of nitrogen (N), 0.01% to 0.5% of manganese (Mn), 12.0% to 19.0% of chrome (Cr), 0.01% to 0.5% of nickel (Ni), 0.3% to 1.5% of copper (Cu), the remainder iron (Fe) and other inevitable impurities,
 wherein a value of Equation (1) during hot rolling satisfies 1,000 or less, Equation (1) being 15*RHT/R4+CT, where RHT (° C.) represents a slab reheating temperature, R4(%) represents a reduction ratio of a R4 stand of rough rolling, and CT (° C.) represents a coiling temperature.   
     
     
         7 . The method according to  claim 6 , wherein the value of Equation (1) satisfies 800 to 1,000. 
     
     
         8 . The method according to  claim 6 , wherein the RHT is below 1,250° C., R4 is above 40%, and CT is below 650° C. 
     
     
         9 . The method according to  claim 6 , wherein a number of carbides having a diameter of 100 nm or more per unit area of a cold-rolled plate is 50 ea/100 μm 2  to 200 ea/100 μm 2 , and an average crystal grain diameter of the cold-rolled plate is 10 μm or less.