Austenitic stainless steel with improved corrosion resistance and machinability and manufacturing method of the same

Abstract

Disclosed is an austenitic stainless steel with improved corrosion resistance and machinability. The austenitic stainless steel with improved corrosion resistance and machinability may comprise, in percent by weight (wt %), 0.05% or less of C (excluding 0), 2% or less of Si (excluding 0), 2% or less of Mn (excluding 0), 0.01% or less of S, 16 to 22% of Cr, 9 to 15% of Ni, 3% or less of Mo (excluding 0), 0.15 to 0.25% of N, 0.004 to 0.06% of B, and the remainder being Fe and inevitable impurities.

What is claimed is: 
     
         1 . An austenitic stainless steel with improved corrosion resistance and machinability comprising, in percent by weight (wt %), 0.05% or less of C (excluding 0), 2% or less of Si (excluding 0), 2% or less of Mn (excluding 0), 0.01% or less of S, 16 to 22% of Cr, 9 to 15% of Ni, 3% or less of Mo (excluding 0), 0.15 to 0.25% of N, 0.004 to 0.06% of B, and the remainder being Fe and inevitable impurities,
 wherein 10 or more BN precipitates are distributed per 100×100 μm 2 .   
     
     
         2 . The austenitic stainless steel according to  claim 1 , wherein 10 or less MnS precipitates are distributed per 100×100 μm 2 . 
     
     
         3 . The austenitic stainless steel according to  claim 2 , wherein a length of a major axis of the MnS precipitates is 1 μm or more. 
     
     
         4 . The austenitic stainless steel according to  claim 1 , further comprising, in percent by weight (wt %), 1% or less of Cu (excluding 0). 
     
     
         5 . The austenitic stainless steel according to  claim 1 , wherein a pitting potential is 300 mV or more. 
     
     
         6 . A manufacturing method of an austenitic stainless steel with improved corrosion resistance and machinability, the manufacturing method comprising:
 heating a stainless steel comprising, in percent by weight (wt %), 0.05% or less of C (excluding 0), 2% or less of Si (excluding 0), 2% or less of Mn (excluding 0), 0.01% or less of S, 16 to 22% of Cr, 9 to 15% of Ni, 3% or less of Mo (excluding 0), 0.15 to 0.25% of N, 0.004 to 0.06% of B, and the remainder being Fe and inevitable impurities at 1,150 to 1,250° C. for 1 hour and 30 minutes or more;   hot rolling the heated stainless steel; and   maintaining the hot-rolled steel at 1,100 to 1,250° C. for 30 seconds or more.