Abstract: Abrasion resistant steel having a chemical composition comprising, by mass %, C: 0.10 to 0.20%, Si: 0.01 to 1.20%, Mn: 0.01 to 2.00%, P: less than 0.017%, S: 0.010% or less, Cu: 0.01 to 0.70%, Ni: 0.01 to 1.00%, Cr: 0 to 1.50%, Mo: 0 to 0.80%, W: 0 to 0.50%, Nb: 0 to 0.050%, V: 0 to 0.20%, Ti: 0 to 0.030%, B: 0 to 0.0030%, N: 0.0001 to 0.0070%, Al: 0.001 to 0.10%, Ca: 0 to 0.0050%, Zr: 0 to 0.0050%, Mg: 0 to 0.0050%, REM: 0 to 0.0050%, and a balance of Fe and impurities, having metal structures at a position of ¼ of the thickness from the surface in a thickness direction, which have a total of the area ratios of martensite and lower bainite of 50 to 100% and a prior austenite average grain size of 5 to 23 ?m, and having a Brinell hardness at a position of 1 mm from the surface in the thickness direction of 360 to 440, and a method for producing the same.

Abstract: A steel plate according to an aspect of the present invention has a predetermined chemical composition, an index Q obtained by Equation (1) is 0.00 or more, a carbon equivalent Ceq (%) obtained by Equation (2) is less than 0.800%, a ratio of a difference between a hardness at a surface layer portion and a hardness at a thickness center portion to the hardness at the surface layer portion at a room temperature is 15.0% or less, the hardness at the suffice layer portion at a room temperature is 400 or more in terms of Vickers hardness, and a steel thickness is 40 or more. Q=0.18?1.3(logT)+0.75(2.7×[C]+[Mn]+0.45×[Ni]+0.

Abstract: In a steel plate according to the present invention, a chemical composition is within a predetermined range, an ? value is 0.13 to 1.0 mass %, a ? value is 8.45 to 15.2, an yield strength is 670 to 870 N/mm2, a tensile strength is 780 to 940 N/mm2, an average grain size at ½t of the steel plate is 35 ?m or less, and a plate thickness is 25 to 200 mm. In the steel plate according to the present invention, in a case where SR is performed on the steel, a charpy absorbed energy at ?40° C. in an area in which SR is performed may be 100 J or more.

Abstract: In a steel plate according to the present invention, a chemical composition is within a predetermined range, an ? value is 0.13 to 1.0 mass %, a ? value is 8.45 to 15.2, an yield strength is 670 to 870 N/mm2, a tensile strength is 780 to 940 N/mm2, an average grain size at ½t of the steel plate is 35 ?m or less, and a plate thickness is 25 to 200 mm. In the steel plate according to the present invention, in a case where SR is performed on the steel, a charpy absorbed energy at ?40° C. in an area in which SR is performed may be 100 J or more.