Lean duplex stainless steel having superb drawing property and method for producing same

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≦2.18 - - - (expression 2)

1 . Lean duplex stainless steel having a superb drawing property comprising, 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,
 wherein, 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 following expressions:
   −30° C.≦Md_SIM10≦0° C.   (expression 1)
 
   2.08≦LDR≦2.18   (expression 2).
 
   
     
     
         2 . The lean duplex stainless steel having a superb drawing property of  claim 1 , wherein an austenite fraction satisfies the following range, and the rest is formed with the ferrite.
   30≦-austenite fraction (γ)≦70
   
     
     
         3 . A method for producing lean duplex stainless steel having a superb drawing property, the method comprising cold annealing steel including, 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 in a range of 950° C. to 1100° C.