ABRASION RESISTANT STEEL PLATE HAVING LOW-TEMPERATURE TOUGHNESS AND HYDROGEN EMBRITTLEMENT RESISTANC

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Provided are an abrasion resistant steel plate having excellent low-temperature toughness and hydrogen embrittlement resistance, and a manufacturing method therefor. The steel plate, which has a Brinell hardness (HBW10/3000) of 401 or more, and a plate thickness of 6-125 mm, contains 50/100 µm2 or more of fine precipitates having a diameter of 50 nm or less in lath-martensite steel that has crystal grains which are surrounded by high angle grain boundaries of a misorientation of 15° or more, and have an average particle size of 20 µm or less. The steel contains, by mass%, C : 0.20-0.30%, Si : 0.05-0.5%, Mn : 0.5-1.5%, Cr : 0.05-1.20%, Nb : 0.01-0.08%, B : 0.0005-0.003%, Al : 0.01-0.08%, N : 0.0005-0.008%, P : 0.05% or less, S : 0.005% or less, and O : 0.008% or less, moreover contains, as required, one or more rare earth elements from among Mo, V, Ti, Nd, Cu, Ni, W, Ca, and Mg, and satisfies 0.03 ≤ Nb+Ti+Al+V ≤ 0.14, with the remainder being constituted by Fe and unavoidable impurities. The steel is cast, and after rolling, is reheated to the Ac3 transformation point or higher, and successively quenched from the Ar3 transformation point or higher to a temperature of 250°C or less by water cooling. As required, the steel is reheated to 1100°C or more, the rolling reduction of a non-recrystallisation region is 30% or more, and the steel is cooled by water cooling to a temperature of 250°C or less, and reheated at a rate of 1°C/s or more to the Ac3 transformation point or higher.