| US 7,527,700 B2 | ||
| High strength hot rolled steel sheet and method for manufacturing the same | ||
| Nobusuke Kariya, Kawasaki (Japan); Shusaku Takagi, Fukuyama (Japan); Tetsuo Shimizu, Chiba (Japan); Tetsuya Mega, Sendai (Japan); Kei Sakata, Handa (Japan); and Hiroshi Takahashi, Chiba (Japan) | ||
| Assigned to JFE Steel Corporation, Tokyo (Japan) | ||
| Appl. No. 10/543,489 PCT Filed Apr. 21, 2004, PCT No. PCT/JP2004/005743 § 371(c)(1), (2), (4) Date Jul. 26, 2005, PCT Pub. No. WO2004/094681, PCT Pub. Date Nov. 04, 2004. |
||
| Claims priority of application No. 2003-115852 (JP), filed on Apr. 21, 2003; and application No. 2004-124154 (JP), filed on Apr. 20, 2004. | ||
| Prior Publication US 2006/0096678 A1, May 11, 2006 | ||
| Int. Cl. C22C 38/00 (2006.01) | ||
| U.S. Cl. 148—320 [148/602] | 4 Claims |
| 1. A high strength hot rolled steel sheet consisting of
0.04 to 0.15% C, 1.5% or less Si, 0.5 to 1.6% Mn, 0.04% or less P, 0.005% or less S, 0.04% or less Al, 0.03 to 0.15% Ti, 0.03
to 0.5% Mo, by mass, and balance of Fe and inevitable impurities, and having a microstructure consisting of ferrite containing
precipitates, second phase of bainite and/or martensite, and other phase,
wherein some of the precipitates in the ferrite containing precipitates contain Ti—Mo compound carbides, and the mean diameter
of the precipitates is 20 nm or less and the mean distance between the precipitates is 60 nm or less,
the hardness of the ferrite determined by a Nano Hardness Tester is 3 to 8 Gpa,
the percentage of the ferrite containing precipitates is 40 to 95%, and the percentage of the other phase is 5% or less, and
the steel sheet has a tensile strength of 780 Mpa or more.
|