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

Abstract

Provided are: a non-oriented electrical steel sheet having outstanding magnetic properties and comprising, as percentages by weight, from 1.0 to 3.0% of Al, from 0.5 to 2.5% of Si, from 0.5 to 2.0% of Mn, from 0.001 to 0.004% of N, from 0.0005 to 0.004% of S 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 {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn])/([N]+[S])}≦1,400; and a production method therefor. By optimising the Al, Si, Mn, N and S added components in this way, the distribution density of coarse inclusions is increased, thereby making it possible to improve crystal-grain growth properties and domain wall mobility and so produce 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 sheet having superior magnetic properties, comprising 0.7˜3.0% of Al, 0.2˜3.5% of Si, 0.2˜2.0% of Mn, 0.001˜0.004% of N, 0.0005˜0.004% of S, and a balance of Fe and other inevitable impurities by wt %, and satisfying at least one of Conditions (1), (2) and (3) below:
 Condition (1): 0.7≦[Al]≦2.7, 0.2≦[Si]≦1.0, 0.2≦[Mn]≦1.7, {[Al]+[Mn]}≦2.0, 0.002≦{[N]+[S]}≦0.006, 230≦{([Al]+[Mn])/([N]+[S])}≦1,000; 
 Condition (2): 1.0≦[Al]≦3.0, 0.5≦[Mn]≦2.0, {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn])/([N]+[S])}1,400; and 
 Condition (3): 1.0≦[Al]≦3.0, 2.3≦[Si]≦3.5, 0.5≦[Mn]≦2.0, {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn])/([N]+[S])}≦1,400, 
 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 , which satisfies Condition (1) and wherein the amounts of Al, Si and Mn satisfy Relation (1) below.
 Relation (1): 1.0≦{[Al]+[Si]+[Mn]/2}≦2.0   
     
     
         3 . The non-oriented electrical steel sheet of  claim 1 , wherein the amounts of Al and Mn satisfy Relation (2) below.
 Relation (2): 1≦[Al]/[Mn]≦8   
     
     
         4 . The non-oriented electrical steel sheet of  claim 2 , wherein a cross-sectional Vickers hardness (Hv1) is 140 or less. 
     
     
         5 . The non-oriented electrical steel sheet of  claim 1 , which satisfies Condition (2) and wherein the amounts of Al, Si and Mn satisfy Relation (3) below.
 Relation (3): 1.7≦{[Al]+[Si]+[Mn]/2}≦5.5   
     
     
         6 . The non-oriented electrical steel sheet of  claim 1 , which satisfies Condition (2) and wherein the amounts of Al and Si satisfy Relation (4) below.
 Relation (4): 0.6≦[Al]/[Si]≦4.0   
     
     
         7 . The non-oriented electrical steel sheet of  claim 5 , wherein a cross-sectional Vickers hardness (Hv1) is 190 or less. 
     
     
         8 . The non-oriented electrical steel sheet of  claim 1 , which satisfies Condition (3) and wherein the amounts of Al, Si and Mn satisfy Relation (5) below.
 Relation (5): 3.0≦{[Al]+[Si]+[Mn]/2}≦56.5   
     
     
         9 . The non-oriented electrical steel sheet of  claim 8 , wherein a cross-sectional Vickers hardness (Hv1) is 225 or less. 
     
     
         10 . 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, and a distribution density of the inclusion having an average size of 300 nm or more is equal to or greater than 0.02 number/mm 2 . 
     
     
         11 . The non-oriented electrical steel sheet of  claim 1 , further comprising 0.2% or less of P. 
     
     
         12 . The non-oriented electrical steel sheet of  claim 11 , wherein an inclusion comprising a nitride and a sulfide alone or a combination thereof is formed in the steel sheet, and a distribution density of the inclusion having an average size of 300 nm or more is equal to or greater than 0.02 number/mm 2 . 
     
     
         13 . 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. 
     
     
         14 . The non-oriented electrical steel sheet of  claim 13 , wherein an inclusion comprising a nitride and a sulfide alone or a combination thereof is formed in the steel sheet, and a distribution density of the inclusion having an average size of 300 nm or more is equal to or greater than 0.02 number/mm 2 . 
     
     
         15 . A non-oriented electrical steel sheet having superior magnetic properties, comprising 0.7˜3.0% of Al, 0.2˜3.5% of Si, 0.2˜2.0% of Mn, 0.001˜0.004% of N, 0.0005˜0.004% of S, and a balance of Fe and other inevitable impurities by wt %, wherein an inclusion comprising a nitride and a sulfide alone or a combination thereof is formed in the steel sheet, and a distribution density of the inclusion having an average size of 300 nm or more is equal to or greater than 0.02 number/mm 2 . 
     
     
         16 . The non-oriented electrical steel sheet of  claim 15 , further comprising 0.2% or less of P. 
     
     
         17 . The non-oriented electrical steel sheet of  claim 15 , further comprising at least one of 0.005˜0.2% of Sn and 0.005˜0.1% of Sb. 
     
     
         18 . A method of producing a non-oriented electrical steel sheet having superior magnetic properties, comprising subjecting a slab comprising 0.7˜3.0% of Al, 0.2˜3.5% of Si, 0.2˜2.0% of Mn, 0.001˜0.004% of N, 0.0005˜0.004% of S, and a balance of Fe and other inevitable impurities by wt % and satisfying at least one of Conditions (1), (2) and (3) below to heating, hot rolling, cold rolling, and final annealing at 750˜1100° C.:
 Condition (1): 0.7≦[Al]≦2.7, 0.2≦[Si]≦1.0, 0.2≦[Mn]≦1.7, {[Al]+[Mn]}≦2.0, 0.002≦{[N]+[S]}≦≦0.006, 230≦{([Al]+[Mn])/([N]+[S])}≦1,000; 
 Condition (2): 1.0≦[Al]≦3.0, 0.5≦[Si]≦2.5, 0.5≦[Mn]≦2.0, {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn])/([N]+[S])}≦1,400; and 
 Condition (3): 1.0≦[Al]≦3.0, 2.3≦[Si]≦3.5, 0.5≦[Mn]≦2.0, {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn])/([N]+[S])}≦1,400, 
 wherein [Al], [Si], [Mn], [N] and [S] indicate amounts (wt %) of Al, Si, Mn, N and S, respectively. 
 
     
     
         19 . The method of  claim 18 , wherein the slab satisfies Condition (1) and the amounts of Al, Si and Mn satisfy Relation (1) below.
 Relation (1): 1.0≦{[Al]+[Si]+[Mn]/2}≦2.0   
     
     
         20 . The method of  claim 18 , wherein the amounts of Al and Mn satisfy Relation (2) below.
 Relation (2): 1≦[Al]/[Mn]≦8   
     
     
         21 . The method of  claim 18 , wherein the slab satisfies Condition (2) and the amounts of Al, Si and Mn satisfy Relation (3) below.
 Relation (3): 1.7≦{[Al]+[Si]+[Mn]/2}≦5.5   
     
     
         22 . The method of  claim 18 , wherein the slab satisfies Condition (2) and the amounts of Al and Si satisfy Relation (4) below.
 Relation (4): 0.6≦[Al]/[Si]≦4.0   
     
     
         23 . The method of  claim 18 , wherein the slab satisfies Condition (3) and the amounts of Al, Si and Mn satisfy Relation (5) below.
 Relation (5): 3.0≦{[Al]+[Si]+[Mn]/2}≦6.5   
     
     
         24 . The method of  claim 18 , wherein an inclusion comprising a nitride and a sulfide alone or a combination thereof is formed in the steel sheet subjected to final annealing, and a distribution density of the inclusion having an average size of 300 nm or more is equal to or greater than 0.02 number/mm 2 . 
     
     
         25 . The method of  claim 18 , wherein the slab is prepared by adding 0.3˜0.5% of Al to perform deoxidation, adding remaining alloy elements, and maintaining a temperature at 1,500˜1,600° C. 
     
     
         26 . The method of  claim 18 , wherein annealing of a hot rolled sheet is performed between the hot rolling and the cold rolling. 
     
     
         27 . The method of  claim 18 , wherein the slab further comprises 0.2% or less of P. 
     
     
         28 . The method of  claim 27 , wherein an inclusion comprising a nitride and a sulfide alone or a combination thereof is formed in the steel sheet, and a distribution density of the inclusion having an average size of 300 nm or more is equal to or greater than 0.02 number/mm 2 . 
     
     
         29 . The method of  claim 18 , wherein the slab further comprises at least one of 0.005˜0.2% of Sn and 0.005˜0.1% of Sb. 
     
     
         30 . The method of  claim 29 , wherein an inclusion comprising a nitride and a sulfide alone or a combination thereof is formed in the steel sheet, and a distribution density of the inclusion having an average size of 300 nm or more is equal to or greater than 0.02 number/mm 2 . 
     
     
         31 . A non-oriented electrical steel sheet slab, comprising 0.7˜3.0% of Al, 0.2˜3.5% of Si, 0.2˜2.0% of Mn, 0.001˜0.004% of N, 0.0005˜0.004% of S, and a balance of Fe and other inevitable impurities by wt %, and satisfying at least one of Conditions (1), (2) and (3) below:
 Condition (1): 0.7≦[Al]≦2.7, 0.2≦[Si]≦1.0, 0.2≦[Mn]≦1.7, {[Al]+[Mn]}≦2.0, 0.002≦{[N]+[S]}≦0.006, 230≦{([Al]+[Mn])/([N]+[S])}≦1,000; 
 Condition (2): 1.0≦[Al]≦3.0, 0.5≦[Si]≦2.5, 0.5≦[Mn]≦2.0, {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn])/([N]+[S])}≦1,400; and 
 Condition (3): 1.0≦[Al]≦3.0, 2.3≦[Si]≦3.5, 0.5≦[Mn]≦2.0, {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn])/([N]+[S])}≦1,400, 
 wherein [Al], [Si], [Mn], [N] and [S] indicate amounts (wt %) of Al, Si, Mn, N and S, respectively. 
 
     
     
         32 . The non-oriented electrical steel sheet slab of  claim 31 , which satisfies Condition (1) and wherein the amounts of Al, Si and Mn satisfy Relation (1) below.
 Relation (1): 1.0≦{[Al]+[Si]+[Mn]/2}≦2.0   
     
     
         33 . The non-oriented electrical steel sheet slab of  claim 31 , wherein the amounts of Al and Mn satisfy Relation (2) below.
 Relation (2): 1≦[Al]/[Mn]≦8   
     
     
         34 . The non-oriented electrical steel sheet slab of  claim 31 , which satisfies Condition (2) and wherein the amounts of Al, Si and Mn satisfy Relation (3) below.
 Relation (3): 1.7≦{[Al]+[Si]+[Mn]/2}≦5.5   
     
     
         35 . The non-oriented electrical steel sheet slab of  claim 31 , which satisfies Condition (2) and wherein the amounts of Al and Si satisfy Relation (4) below.
 Relation (4): 0.6≦[Al]/[Si]≦4.0   
     
     
         36 . The non-oriented electrical steel sheet slab of  claim 31 , which satisfies Condition (3) and wherein the amounts of Al, Si and Mn satisfy Relation (5) below.
 Relation (5): 3.0≦{[Al]+[Si]+[Mn]/2}≦6.5   
     
     
         37 . The non-oriented electrical steel sheet slab of  claim 31 , further comprising 0.2% or less of P. 
     
     
         38 . The non-oriented electrical steel sheet slab of  claim 31 , further comprising at least one of 0.005˜0.2% of Sn and 0.005˜0.1% of Sb. 
     
     
         39 . A method of producing a non-oriented electrical steel sheet slab, comprising adding 0.3˜0.5% of Al to molten steel to perform deoxidation, adding a remainder of Al and Si and Mn, and maintaining a temperature of the molten steel at 1,500˜1,600° C., thus obtaining the slab comprising 0.7˜3.0% of Al, 0.2˜3.5% of Si, 0.2˜2.0% of Mn, 0.001˜0.004% of N, 0.0005˜0.004% of S, and a balance of Fe and other inevitable impurities by wt %, and satisfying at least one of Conditions (1), (2) and (3) below:
 Condition (1): 0.7≦[Al]≦2.7, 0.2≦[Si]≦1.0, 0.2≦[Mn]≦1.7, {[Al]+[Mn]}≦2.0, 0.002≦{[N]+[S]}≦0.006, 230≦{([Al]+[Mn])/([N]+[S])}≦1,000; 
 Condition (2): 1.0≦[Al]≦3.0, 0.5≦[Si]≦2.5, 0.5≦[Mn]≦2.0, {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn])/([N]+[S])}≦1,400; and 
 Condition (3): 1.0≦[Al]≦3.0, 2.3[Si]≦3.5, 0.5≦[Mn]≦2.0, {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn])/([N]+[S])}≦1,400, 
 wherein [Al], [Si], [Mn], [N] and [S] indicate amounts (wt %) of Al, Si, Mn, N and S, respectively. 
 
     
     
         40 . The method of  claim 39 , wherein the slab further comprises 0.2% or less of P. 
     
     
         41 . The method of  claim 39 , wherein the slab further comprises at least one of 0.005˜0.2% of Sn and 0.005˜0.1% of Sb.