| abstract |
A high-strength hot-rolled steel sheet having a small fluctuation in mechanical properties in a coil and excellent stretch flangeability is provided. SOLUTION: In mass%, C: more than 0.010%, 0.06% or less, Si: 0.3% or less, Mn: 0.8% or less, P: 0.03% or less, S: 0.02% or less, Al: 0.1% or less, N: 0.01 % Or less, Ti: 0.05 to 0.10%, and the composition is composed of the remaining Fe and inevitable impurities. Si and Mn are reduced as much as possible, segregation and the like are reduced, and strength fluctuation due to the difference in position in the coil is reduced. Furthermore, the steel sheet structure is a structure in which the ferrite phase occupies 95% or more in area ratio, the ferrite crystal grains have an average grain size of 1 μm or more, and TiC having an average grain size of 7 nm or less is dispersed in the ferrite crystal grains. And As a result, it is possible to obtain a high-strength hot-rolled steel sheet that maintains a yield strength of 530 MPa or more, has small fluctuations in mechanical properties in the coil, and has excellent stretch flangeability. [Selection figure] None |