Non-Oriented Electrical Steel Sheet Having Superior Magnetic Properties and a Production Method Therefor

Abstract

A non-oriented electrical steel sheet having outstanding magnetic properties and i, as percentages by weight, from 0.7˜3.02.5% of Al, 0.2˜32.5% of Si, 0.2˜2.01.5% of Mn, 0.001 0005˜0.004% of N, 0.0005˜0.004% of S, 0.003% or less of C, and a balance of Fe and other unavoidably incorporated impurities, wherein the Al, Mn, N and S are included so as to satisfy the compositional formulae 1≤{[Al]+[Mn]}≤3.5, 0.002≤{[N]+[S]}≤0.006, 300250≤{([Al]+[Mn])/([N]+[S])}≤1,400, 1.4≤{[Al]+[Si]+[Mn]/2}≤5.5, 1 [Al]/[Si]≤7.5, 1≤[Al]/[Mn]≤3.7; and a production method therefor. By optimising the Al, Si, Mn, N and S added components, the distribution density of coarse inclusions is increased, thereby improving the crystal-grain growth properties and domain wall motility and producing the highest grade of non-oriented electrical steel sheet having superior magnetic properties, low hardness, and superior customer workability and productivity.

1 . A non-oriented electrical steel, comprising 0.7˜2.5% of Al, 0.2˜2.5% of Si, 0.2˜1.5% of Mn, 0.0005˜0.004% of N, 0.0005˜0.004% of S, 0.003% or less of C, and a balance of Fe and other inevitable impurities by wt %, and satisfying the conditions below:
 Conditions: 
 1≤{[Al]+[Mn]}≤3.5 
 0.002≤{[N]+[S]}≤0.006, 
 250≤{([Al]+[Mn])/([N]+[S])}≤1,400, 
 1.4≤{[Al]+[Si]+[Mn]/2}≤5.5, 
 1≤[Al]/[Si]≤7.5, and 
 1≤[Al]/[Mn]≤3.7, 
 wherein [Al], [Si], [Mn], [N] and [S] indicate amounts (wt %) of Al, Si, Mn, N and S, respectively. 
 
     
     
         2 . The non-oriented electrical steel sheet of  claim 1 , further comprising 0.2% or less of P. 
     
     
         3 . The non-oriented electrical steel sheet of  claim 1 , further comprising at least one of 0.005˜0.2% of Sn and 0.005˜0.1% of Sb. 
     
     
         4 . The non-oriented electrical steel sheet of  claim 1 , further comprising 0.004% or less of Ti. 
     
     
         5 . The non-oriented electrical steel sheet of  claim 1 , wherein an inclusion comprising a nitride and a sulfide alone or a combination thereof is formed in the steel sheet. 
     
     
         6 . The non-oriented electrical steel sheet of  claim 5 , wherein the nitride comprises aluminum nitride and the sulfide comprises magnesium sulfide. 
     
     
         7 . The non-oriented electrical steel sheet of  claim 5 , wherein the inclusion having an average size of 300 nm or more. 
     
     
         8 . The non-oriented electrical steel sheet of  claim 5 , wherein a distribution density of the inclusion having a size of 300 nm or more is equal to or greater than 0.02 number/mm 2 . 
     
     
         9 . The non-oriented electrical steel sheet of  claim 1 , wherein a cross-sectional Vickers hardness (Hv1) is 190 or less.