| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet, a hot dip galvanized steel sheet, a hot dip galvannealed steel sheet and a steel pipe each having a low yield ratio and a high Young's modulus in the rolling direction measured by a static stretching method, and to provide methods for producing them. SOLUTION: A low yield ratio high Young's modulus steel sheet having a composition comprising, by mass,≤0.01% N, 0.005 to 0.10% Nb and 0.002 to 0.15% Ti, in which Ti and N satisfy Ti-48/14×N≥0.0005, the total volume ratio of either or both ferrite and bainite is >50%, the volume ratio of martensite is 2 to 25%, and, at the position in which the distance to the sheet thickness direction from the surface of the steel sheet is 1/6 the sheet thickness, the total of the X-ray random intensity ratio in the ä100}<001> orientation and the X-ray random intensity ratio in the ä110}<001> orientation is≤5, and the total of the maximum value of the X-ray random intensity ratios in the group of the ä110}<111> orientation to the ä110}<112> orientation and the X-ray random intensity ratio in the ä211}<111> orientation is≥5. COPYRIGHT: (C)2009,JPO&INPIT
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