Soft high-silicon steel sheet and manufacturing method thereof

Abstract

The present invention relates to a soft high-silicon steel sheet, and more particularly, to a soft high-silicon steel sheet which has ductility even if the silicon content thereof is greater than 4%, and can thus be manufactured into a steel sheet having a high silicon content only by means of rolling without an additional siliconizing process. The soft high-silicon steel sheet may include a silicon content greater than 4 wt % and less than or equal to 7 wt % and 1 to 20% of chromium, or may include 5 to 7 wt % of Si+Al and 1 to 20 wt % of chromium.

1 - 14 . (canceled) 
     
     
         15 . A soft high-silicon steel sheet comprising, by wt %, silicon (Si): greater than 4% to 7%, chromium (Cr): 1% to 20%, and boron (B): 0.01% to 0.05%. 
     
     
         16 . The soft high-silicon steel sheet of  claim 15 , further comprising total aluminum (Al) in an amount of 0.1 wt % to 3 wt %. 
     
     
         17 . The soft high-silicon steel sheet of  claim 16 , wherein a content of Si+total Al in the soft high-silicon steel sheet is within a range of greater than 4.1% to 7%. 
     
     
         18 . The soft high-silicon steel sheet of  claim 15 , further comprising at least one selected from molybdenum (Mo): 0.1% or less, nickel (Ni): 0.01% or less, phosphorus (P): 0.05% or less, and copper (Cu): 0.01% or less. 
     
     
         19 . The soft high-silicon steel sheet of  claim 16 , further comprising at least one selected from molybdenum (Mo): 0.1% or less, nickel (NI): 0.01% or less, phosphorus (P): 0.05% or less, and copper (Cu): 0.01% or less. 
     
     
         20 . The soft high-silicon steel sheet of  claim 17 , further comprising at lest one selected from molybdenum (Mo): 0.1% or less, nickel (Ni): 0.01% or less, phosphorus (P): 0.05% or less, and copper (Cu): 0.01% or less. 
     
     
         21 . The soft high-silicon steel sheet of  claim 15 , wherein respective contents of carbon (C) and nitrogen (N) in the soft high-silicon steel sheet is adjusted to 0.05% or less. 
     
     
         22 . The soft high-silicon steel sheet of  claim 16 , wherein respective contents of carbon (C) and nitrogen (N) in the soft high-silicon steel sheet is adjusted to 0.05% or less. 
     
     
         23 . A method of manufacturing a soft high-silicon steel sheet, the method comprising:
 preparing a steel material comprising, by wt %, silicon (Si): greater than 4% to 7% and chromium (Cr): 1% to 20%;   forming a hot rolled steel sheet by hot rolling the steel material at a temperature of 800° C. or higher; and   cold rolling the hot rolled steel sheet within a temperature range of 150° C. to 300° C.   
     
     
         24 . The method of  claim 23 , wherein the steel material further comprises total aluminum (Al) in an amount of 0.1 wt % to 3 wt %. 
     
     
         25 . The method of  claim 24 , wherein a content of Si+total Al in the steel material is within a range of greater than 4.1% to 7%. 
     
     
         26 . The method of  claim 23 , wherein respective contents of carbon (C) and nitrogen (N) in the steel material is adjusted to be 0.05% or less. 
     
     
         27 . The method of  claim 24 , wherein respective contents of carbon (C) and nitrogen (N) in the steel material is adjusted to be 0.05% or less. 
     
     
         28 . The method of  claim 25 , wherein respective contents of carbon (C) and nitrogen (N) in the steel material is adjusted to be 0.05% or less. 
     
     
         29 . The method of  claim 23 , wherein the steel material further comprises at least one selected from molybdenum (Mo): 0.1% or less, nickel (Ni): 0.01% or less, phosphorus (P): 0.05% or less, and copper (Cu): 0.01% or less. 
     
     
         30 . The method of  claim 24 , wherein the steel material further comprises at least one selected from molybdenum (Mo): 0.1% or less, nickel (Ni): 0.01% or less, phosphorus (P); 0.05% or less, and copper (Cu): 0.01% or less. 
     
     
         31 . The method of  claim 25 , wherein the steel material further comprises at least one selected from molybdenum (Mo): 0.1% or less, nickel (Ni): 0.01% or less, phosphorus (P): 0.05% or less, and copper (Cu): 0.01% or less. 
     
     
         32 . The method of  claim 23 , wherein the steel material is prepared by a continuous casting method or a strip casting method. 
     
     
         33 . The method of  claim 23 , wherein microstructural grains of the hot rolled steel sheet steel have a size within a range of 150 μm to 250 μm. 
     
     
         34 . The method of  claim 23 , wherein the forming of the hot rolled steel sheet comprises cooling the hot rolled steel sheet from 800° C. to 100° C. at a cooling rate of 30° C./sec or higher after the hot rolling of the steel material. 
     
     
         35 . The method of  claim 23 , wherein after the forming of the hot rolled steel sheet, the method further comprises heat treating the hot rolled steel sheet within a temperature range of 800° C. to 1200° C. and then cooling the hot rolled steel sheet from 800° C. to 100° C. at a cooling rate of 30° C./sec or higher.