Non-magnetic austenitic stainless steel having excellent corrosion resistance and manufacturing method therefor

Abstract

Disclosed is a non-magnetic austenitic stainless steel with excellent corrosion resistance which is applicable to an environment requiring corrosion resistance along with excellent non-magnetic properties, and manufacturing method thereof. The non-magnetic austenitic stainless steel with excellent corrosion resistance according to an embodiment of the present disclosure includes, in percent (%) by weight of the entire composition, C: 0.05% or less, Si: 1.0% or less, Mn: 0.5 to 2.0%, Cr: 16 to 24%, Ni: 10 to 16%, N: 0.2% or less, the remainder of iron (Fe) and other inevitable impurities, and satisfies a following equation (1). Ni≥−2.7−5.8*C−1.77*Si−0.066*Mn+0.893*Cr+1.05*Mo−0.88*Cu−13.8*N  (1)

1 . A non-magnetic austenitic stainless steel with excellent corrosion resistance, the austenitic stainless steel comprising, in percent (%) by weight of the entire composition, C: 0.05% or less, Si: 1.0% or less, Mn: 0.5 to 2.0%, Cr: 16 to 24%, Ni: 10 to 16%, N: 0.2% or less, the remainder of iron (Fe) and other inevitable impurities, and
 wherein the austenitic stainless steel satisfies a following equation (1), and has a permeability of 1.02μ or less.
   Ni≥−2.7−5.8*C−1.77*Si−0.066*Mn+0.893*Cr+1.05*Mo−0.88*Cu−13.8*N  (1)
 
   (Ni, C, Si, Mn, Cr, Mo, Cu, N mean the content (% by weight) of each element)   
     
     
         2 . The austenitic stainless steel of  claim 1 , further comprising: in percent (%) by weight, Cu: 3.0% or less. 
     
     
         3 . The austenitic stainless steel of  claim 1 , further comprising: in percent (%) by weight, Mo: 4.0% or less. 
     
     
         4 . The austenitic stainless steel of  claim 1 , further comprising: in percent (%) by weight, B: less than 0.01%. 
     
     
         5 . The austenitic stainless steel of  claim 1 , wherein the stainless steel satisfies a calculated δ-ferrite fraction represented by the following equation (2) of 0% or less.
   161*{[Cr+Mo+1.5*Si+18]/[Ni+30*(C+N)+0.5*(Cu+Mn)+36]+0.262}−161  (2)
 
 (Cr, Mo, Si, Ni, C, N, Cu, Mn mean the content (% by weight) of each element) 
 
     
     
         6 . The austenitic stainless steel of  claim 1 , wherein the stainless steel satisfies a pitting resistance equivalent number (PREN) represented by the following equation (3) of the range of 20 to 30.
   Cr+3.3*Mo+30*N−Mn+Si  (3)
   (Cr, Mo, N, Mn, Si mean the content (% by weight) of each element)   
     
     
         7 . The austenitic stainless steel of  claim 1 , wherein the stainless steel satisfies a σ phase formation index represented by the following equation (4) of the range of 18 to 24.
   Cr+Mo+3*Si  (4)
 
 (Cr, Mo, Si mean the content (% by weight) of each element) 
 
     
     
         8 . The austenitic stainless steel of  claim 1 , wherein the stainless steel has a permeability of 1.012μ or less. 
     
     
         9 . The austenitic stainless steel of  claim 1 , wherein an average grain size of the stainless steel is 1.012μ or less. 
     
     
         10 . A manufacturing method of a non-magnetic austenitic stainless steel with excellent corrosion resistance, the manufacturing method comprising:
 hot rolling the slab comprising, in percent (%) by weight of the entire composition, C: 0.05% or less, Si: 1.0% or less, Mn: 0.5 to 2.0%, Cr: 16 to 24%, Ni: 10 to 16%, N: 0.2% or less, the remainder of iron (Fe) and other inevitable impurities and satisfying a σ phase formation index represented by the following equation (4) of the range of 18 to 24; and   performing a solution heat treatment of the hot rolled material.
   Cr+Mo+3*Si  (4)
 
   (Cr, Mo, Si mean the content (% by weight) of each element)   
     
     
         11 . The manufacturing method of  claim 10 , wherein the slab satisfies a following equation (1), and satisfies a calculated δ-ferrite fraction represented by a following equation (2) of 0% or less.
   Ni≥−2.7−5.8*C−1.77*Si−0.066*Mn+0.893*Cr+1.05*Mo−0.88*Cu−13.8*N  (1)
 
   161*{[Cr+Mo+1.5*Si+18]/[Ni+30*(C+N)+0.5*(Cu+Mn)+36]+0.262}−161  (2)
 
 (Ni, C, Si, Mn, Cr, Mo, Cu, N mean the content (% by weight) of each element). 
 
     
     
         12 . The manufacturing method of  claim 10 , wherein the solution heat treatment is performed at 1,100 to 1,150° C. for 60 to 120 seconds.