Abstract: One aspect of the steel sheet having high Young's modulus includes in terms of mass %, C: 0.0005 to 0.30%, Si: 2.5% or less, Mn: 2.7 to 5.0%, P: 0.15% or less, S: 0.015% or less, Mo: 0.15 to 1.5%, B: 0.0006 to 0.01%, and Al: 0.15% or less, with the remainder being Fe and unavoidable impurities, wherein one or both of {110}<223> pole density and {110}<111> pole density in the ? sheet thickness layer is 10 or more, and a Young's modulus in a rolling direction is more than 230 GPa. Another aspect of the steel sheet having high Young's modulus includes, in terms of mass %, C: 0.0005 to 0.30%, Si: 2.5% or less, Mn: 0.1 to 5.0%, P: 0.15% or less, S: 0.015% or less, Al: 0.15% or less, N: 0.01% or less, and further comprises one or two or more of Mo: 0.005 to 1.5%, Nb: 0.005 to 0.20%, Ti: at least 48/14×N (mass %) and 0.2% or less, and B: 0.0001 to 0.01%, at a total content of 0.015 to 1.

Abstract: High yield ratio high-strength thin steel sheet D superior in weldability and ductility characterized by; being comprised of steel containing, by mass %, C: over 0.030 to less than 0.10%, Si: 0.30 to 0.80%, Mn: 1.7 to 3.2%, P: 0.001 to 0,02%, S: 0.0001 to 0.006%, Al: 0.060% or less, N: 0.0001 to 0.0070%, containing further c Ti: 0.01 to 0.055%, Nb: 0.012 to 0.055%, Mo: 0.07 to 0.55%, B: 0.0005 to 0.0040%, and simultaneously statisfying 1.1?14×Ti(%)+20×Nb(%)+3×Mo(%)+300×B(%)?3.7, the balance comprised of iron and unavoidable impurities, and having a yield ratio of 0.64 to less than 0.92, a TS×El of 3320 or more, an YR×TS×El1/2 of 2320 or more, and a maximum tensile strength (TS) of 780 MPa or more.

Abstract: A high-strength steel sheet suitable for deep drawing, characterized by comprising 0.04 to 0.25 mass % of C and 0.3 to 3.0 mass %, in total, of at least one of Si and Al, the steel sheet having multiple phases structure comprising ferrite as a main phase (a phase having the highest volume fraction), not less than 3 vol. % of austenite, and bainite and martensite; said steel satisfying a requirement that a value obtained by dividing volume fraction of Vg (vol. %) of austenite before working by the content of C (mass %) contained in the whole steel, Vg/C, is 40 to 140, a requirement that Vp (volume fraction of austenite at the time of plane strain tensile deformation)/Vs (volume fraction of austenite at the time of shrink flanging deformation) is not more than 0.