Abrasion resistant steel plate having low-temperature toughness and hydrogen embrittlement resistance, and manufacturing method therefor

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 [mu]m2 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 1 degree or more, and have an average particle size of 20 [mu]m 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 degrees centigrade or less by water cooling. As required, the steel is reheated to 1100 degrees centigrade 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 degrees centigrade or less, and reheated at a rate of 1 degree centigrade/s or more to the Ac3 transformation point or higher.