| 摘要 |
PROBLEM TO BE SOLVED: To improve the ductility and hole expansibility of a hot rolled steel sheet.SOLUTION: Disclosed is a hot rolled steel sheet having a chemical composition comprising 0.005 to 0.3% of C, 0.02 to 3.0% of Si, 0.7 to 4.0% of Mn, 0.20% or less of P, 0.010% or less of S, 0.001 to 1.0% sol.Al and 0.01% or less of N and a steel structure composed of ferrite of 40 area% or more at a depth position of the 1/4 of the sheet thickness from the surface of the steel sheet and a second phase and satisfying D≤7.0 and 1.0≤D≤8/(100×C×Mn)(D denotes the average grain size (μm) of the ferrite; and C and Mn denote the mass% of the C and Mn), and also having a texture where, in the central position of the sheet thickness, I{111}≥1.2 and I{111}-I{100}-I{211}≥-3.2(I{111} I{100} and I{211} respectively denote the diffraction X-ray intensity ratio to random samples in the {111}, {100} and {211} orientations, respectively) and in which the maximum value of the value of the diffraction X-ray intensity ratio to the random samples of the {211}<011> to {100}<011> orientation groups is 8.0 or less. |
