Multilayer steel and method for producing multilayer steel
AssigneeThe University of Tokyo
InventorsToshihiko Koseki, Toshio Suzuki, Toyonobu Yoshida, Junya Inoue, Mitsuyuki Tanaka
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Abstract
Disclosed is a multilayered steel composite which compatibly achieves properties such as strength and ductility that are incompatible in conventional steels and is excellent in strength, ductility, weldability, toughness and fatigue strength. Also, disclosed is a method for producing the multilayered steel which is produced by rolling with least two kinds of steels having different chemical compositions and microstructure or different mechanical properties, in combination.
Claims15
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.
A method for producing a multilayered steel, comprising the steps of:
- preparing a plate-shaped first layer serving as an even-numbered layer and comprising, at least, by mass %, 0.05 to 0.4 C, 0.05 to 3.0 Si, 0.05 to 3.0 Mn and unavoidable impurities;
- preparing 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;
- sequentially and alternately stacking the first layer and the second layer in an odd number of layers such that the first layer is sandwiched between the second layers, thus preparing a multilayered steel material having at least five layers with the second layers disposed on outer surfaces thereof;
- and
- rolling and heat treating the multilayered steel material,
- 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.
Dependencies are inferred from the claim text.