To provide a hot rolled steel sheet having reduced in-plane anisotropy of r-value suitable for drawing, and to provide a method for stably producing the same.
A steel sheet having a steel composition comprising, by mass, 0.01 to 0.10% C, 0.10% Si, 0.10 to 0.60% Mn, 0.03% P, 0.020% S, 0.004 to 0.10% sol.Al and 0.0050% N, and the balance Fe with impurities is finished at a temperature which is not lower than dynamic Ar3 upon hot rolling, thus its in-plane anisotropy is improved in such a manner that it has a steel structure where a difference between the maximum crystal grain size of ferrite in the surface layer part from the surface of the sheet to a depth position of 1/4 in the sheet thickness and the maximum crystal grain size of ferrite in the central part from a depth position of 1/4 in the sheet thickness to the center of the sheet thickness is controlled to 10 m, and further, the absolute value of r is controlled to 0.25.
TAKEE YASUHIKO
JPH09176742A | 1997-07-08 | |||
JPH02209424A | 1990-08-20 | |||
JPH0211720A | 1990-01-16 |
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