Wear resistant steel material excellent in toughness and internal quality, and method for manufacturing same

Abstract

The present invention relates to a wear resistant steel material which can be suitably used for industrial machinery, structural materials, steel materials for slurry pipes, sour steel materials, mining, transportation and storage fields, etc. in the oil gas industry which require properties such as ductility and wear resistance. More particularly, the present invention relates to a wear resistant steel material excellent in toughness and internal quality, and a method for manufacturing the same.

1 . A wear resistant steel material having excellent toughness and internal quality, comprising:
 carbon (C): 0.6 wt % to 1.3 wt %, manganese (Mn): 14 wt % to 22 wt %, a balance of iron (Fe) and other unavoidable impurities, and   having a microstructure including carbides in an area fraction of 5% or less (including 0%) and residual austenite.   
     
     
         2 . The wear resistant steel material having excellent toughness and internal quality of  claim 1 , wherein the steel material includes manganese (Mn) greater than 15 wt %. 
     
     
         3 . The wear resistant steel material having excellent toughness and internal quality of  claim 1 , wherein the steel material has a degree of segregation of manganese (Mn), represented by Relationship 1, of 1.16 or less.
   Degree of segregation of Mn=(Mn element in a central portion of a steel material)/(Mn element in molten steel)  [Relationship 1]
   where, in Relationship 1, a central portion of a steel material refers to a region of the steel material, located above and below a ½t position in a thickness direction, by 50 μm or less,   where t refers to a thickness (mm).   
     
     
         4 . A method for manufacturing a wear resistant steel material having excellent toughness and internal quality, comprising:
 reheating a steel slab including carbon (C): 0.6 wt % to 1.3 wt %, manganese (Mn): 14 wt % to 22 wt %, a balance of iron (Fe) and other unavoidable impurities;   manufacturing a hot-rolled steel plate by finish hot rolling the steel slab, having been reheated, at 850° C. to 1050° C.; and   cooling the hot-rolled steel plate at a cooling rate of 5° C./s or more to 600° C. or less,   wherein the reheating is performed at a temperature (T, ° C.), represented by Relationship 2, or less.
   T(° C.)=1446−(174.459×C)−(3.9507×Mn)  [Relationship 2]
 
   where, in Relationship 2, C and Mn refer to the weight content of the element.   
     
     
         5 . The method for manufacturing a wear resistant steel material having excellent toughness and internal quality of  claim 4 , wherein the steel slab includes manganese (Mn) greater than 15 wt %. 
     
     
         6 . The method for manufacturing a wear resistant steel material having excellent toughness and internal quality of  claim 4 , wherein the hot-rolled steel plate has a thickness of 10 mm to 80 mm.