| 摘要 |
PROBLEM TO BE SOLVED: To provide a low yield ratio high tensile steel plate excellent in high temperature strength and weldability.SOLUTION: There is provided a low yield ratio high tensile steel sheet excellent in high temperature strength and weldability, having a component composition containing, by mass%, C:0.04 to 0.12%, Si:0.50% or less, Mn:0.50 to 1.50%, P:0.02% or less, S:0.0050% or less, Al:0.050% or less, Mo:0.40 to 0.70%, V:0.070 to 0.120%, Cr:0.01 to 0.40% and Ceq defined by a formula (1) satisfying 0.46 or less, and the balance Fe with inevitable impurities and having ferrite as a main phase with area percentage of 60% or more, further average crystal particle diameter of ferrite of 5 to 70 μm and yield strength at 600°C of 217 MPa or more.SELECTED DRAWING: None |
