Patent ID: 8137819

Claim:
A multilayered steel comprising: a plate-shaped first layer serving as an even-numbered layer and comprising, by mass %, at least 0.05 to 0.4 C, 0.05 to 3.0 Si, 0.05 to 3.0 Mn and unavoidable impurities; and a plate-shaped second layer serving as an odd-numbered layer and comprising at least one of a steel C comprising at least, by mass %, 0.01 to 0.15 C, 0.01 to 1.0 Si, 0.01 to 2.0 Mn, 12.0 to 24.0 Cr, 4.0 to 14.0 Ni, and 0.001 to 0.3 N, and unavoidable impurities and a steel E comprising at least, by mass %, 0.001 to 0.15 C, 0.05 to 3.0 Si, 15.0 to 32.0 Mn and unavoidable impurities, wherein the first layer and the second layer are sequentially and alternately stacked in an odd number of layers such that the first layer is sandwiched between the second layers, thus obtaining a multilayered steel material having at least five layers with the second layers disposed on outer surfaces thereof, the multilayered steel material being rolled and treated with heat, and wherein the first layer has martensite phase having high strength and low ductility as a main phase, and the second layer has at least one of austenite and ferrite phases having low strength and high ductility as a main phase.