| 摘要 |
There is provided a high-stiffness high-strength thin steel sheet having a tensile strength of not less than 590 MPa and a Young's modulus of not less than 225 GPa, which comprises C: 0.02-0.15%, Si: not more than 1.5%, Mn: 1.5-4.0%, P: not more than 0.05%, S: not more than 0.01%, Al: not more than 1.5%, N: not more than 0.01% and Nb: 0.02-0.40% as mass%, provided that C, N and Nb contents satisfy 0.01 ‰¤C+(12/14)×N-(12/92.9)×Nb ‰¤ 0.06 and N ‰¤ (14/92.9)×(Nb-0.01) and the remainder being substantially iron and inevitable impurities, and has a texture comprising a ferrite phase as a main phase and having a martensite phase at an area ratio of not less than 1%. |
