Ferritic stainless steel having improved magnetic properties and manufacturing method therefor

Abstract

Disclosed herein are ferritic stainless steel and a manufacturing method wherein the ferritic stainless steel has magnetic properties improved by controlling alloy components and a manufacturing process in order to increase responsiveness to an externally applied magnetic field. The ferritic stainless steel having improved magnetic properties according to an embodiment of the present invention may comprise, by % by weight, C: 0% (exclusive) to 0.02% (inclusive), N: 0% (exclusive) to 0.02% (inclusive), Si: 0.5% to 2.0% (both inclusive), Mn: 0.1% to 0.3% (both inclusive), Cr: 16.0% to 20.1% (both inclusive), Mo: 1.0% (exclusive) to 2.0% (inclusive), Ti: 0.1% to 0.4% (both inclusive), and the balance of iron (Fe) and inevitable impurities.

1 . A ferritic stainless steel having enhanced magnetic properties comprising:
 in percent by weight (wt %), more than 0 to 0.02% of C, more than 0 to 0.02% of N, 0.5 to 2.0% of Si, 0.1 to 0.3% of Mn, 16.0 to 20.1% of Cr, more than 1.0 to 2.0% of Mo, 0.1 to 0.4% of Ti, and the remainder having Fe and other unavoidable impurities,   wherein a value of the following formula (1) is 130 or less:
   30+2500*([C]+[N])−15*[Si]+2.5*[Cr]+22*[Mo]  formula (1):
 
   (in formula (1), [C], [N], [Si], [Cr] and [Mo] each refer to a content (wt %) of the element).   
     
     
         2 . The ferritic stainless steel having enhanced magnetic properties of  claim 1 , wherein a value of the following formula (2) is 50 or less:
   18+800*([C]+[N])−6*[Si]+[Cr]+6*[Mo]  Formula (2):
   (in formula (2), [C], [N], [Si], [Cr] and [Mo] each refer to a content (wt %) of the element).   
     
     
         3 . The ferritic stainless steel having enhanced magnetic properties of  claim 1 , further comprising, in percent by weight (wt %), more than 0 to 0.1% of Nb and more than 0% to 0.1% of Sn. 
     
     
         4 . The ferritic stainless steel having enhanced magnetic properties of  claim 1 , wherein a maximum magnetic permeability in the 50 Hz frequency band is 1,000 or more. 
     
     
         5 . The ferritic stainless steel having enhanced magnetic properties of  claim 1 , wherein an externally applied magnetic field is 130 A/m or less to exhibit a maximum magnetic permeability. 
     
     
         6 . The ferritic stainless steel having enhanced magnetic properties of  claim 1 , wherein coercivity is less than 50 A/m on condition of exhibiting a maximum magnetic permeability in a 50 Hz frequency band. 
     
     
         7 . The ferritic stainless steel having enhanced magnetic properties of  claim 1 , wherein a pitting potential value is 300 mV or more. 
     
     
         8 . The ferritic stainless steel having enhanced magnetic properties of  claim 1 , wherein hardness is 140 Hv or more. 
     
     
         9 . A method of manufacturing a ferritic stainless steel having enhanced magnetic properties, the method comprising:
 manufacturing a slab comprising, in percent by weight (wt %), more than 0 to 0.02% of C, more than 0 to 0.02% of N, 0.5 to 2.0% of Si, 0.1 to 0.3% of Mn, 16.0 to 20.1% of Cr, more than 1.0 to 2.0% of Mo, 0.1 to 0.4% of Ti, and the remainder having Fe and other unavoidable impurities, wherein a value of formula (1) below is 130 or less and a value of following formula (2) below is 50 or less;   manufacturing a hot-rolled material by hot-rolling the slab at a reheating temperature of 1050 to 1150° C.;   manufacturing a cold-rolled material by cold-rolling the hot-rolled material; and   finally annealing the cold-rolled material at 1050 to 1150° C.:
   30+2500*([C]+[N])−15*[Si]+2.5*[Cr]+22*[Mo]  formula (1):
 
   (in formula (1), [C], [N], [Si], [Cr] and [Mo] each refer to a content (wt %) of the element)
   18+800*([C]+[N])−6*[Si]+[Cr]+6*[Mo]  formula (2):
 
   (in formula (2), [C], [N], [Si], [Cr] and [Mo] each refer to a content (wt %) of the element).   
     
     
         10 . The method of manufacturing a ferritic stainless steel having enhanced magnetic properties of  claim 9 , wherein the cold-rolling is performed at a reduction rate of 70% or more.