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AssigneeNKK Corporation
InventorsHiroshi Nakata, Tadashi Inoue, Hiroyasu Kikuchi, Sadanori Imada, Akira Hiura, Takeshi Nakahara, Satoshi Ishijima, Yoshimasa Funakawa, Toru Inazumi
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A high tensile strength hot-rolled steel sheet comprises 0.04 to 0.09% C, 0.1% or less Si, 0.5 to 1.5% Mn, 0.02% or less P, 0.01% or less S, 0.1% or less Al, 0.001 to 0.008% N, and 0.01 to 0.15% Ti, by mass %, the content of ingredient there each satisfying the equation (1), and the ferritic grain size α (μm) satisfying the equation (2): [C]+7×[Si]+0.1×[Mn]+[P]+14×[S]+1.75×[Al] +23×[N]+[Ti]+18×[O]+7×[Cu]+18×[Sn]+7×[Mo]+ 1.7×[Cr]+70×[B]+7×[Ca]+14×[Zr]+14×[V]+7×[Nb] ≦2 (1) 3≦α≦60×[Ti]+8 (2) where, [X] denotes the content (mass %) of element X. This hot-rolled steel sheet has excellent workability, high magnetic permeability and high magnetic flux density in a strong magnetic field, and has 490 MPa or higher strength, and is suitable for large electric equipment such as a rotor of generator.
A high tensile strength hot-rolled steel sheet comprising 0.04 to 0.09% C, 0.1% or less Si, 0.5 to 1.5% Mn, 0.02% or less P, 0.01% or less S, 0.1% or less Al, 0.001 to 0.008% N, 0.01 to 0.15% Ti, by mass %, and the balance being iron and inevitable impurities, whereby the content of alloying elements X satisfies the following equation (1), and the ferritic grain size α (μm) satisfies the following equation (2):
Dependencies are inferred from the claim text.