Title:
PRODUCTION OF HIGH STRENGTH AND HIGH WORKABILITY HOT ROLLED STEEL SHEET EXCELLENT IN IMPACT RESISTANCE
Document Type and Number:
Japanese Patent JP3400351
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To obtain a hot rolled steel sheet having excellent formability and impact resistance by subjecting a steel slab having a specified compsn. to rolling and cooling under specified temp. conditions and forming the structure of the steel into the one in which secondary phases composed of martensite, acicular ferrite and residual austenite are allowed to contain in the main phases of pro-eutectoid ferrite.
SOLUTION: The compsn. of the steel slab is composed of, by mass, 0.05 to 0.40% C, 1.0 to 3.0% Si, 0.6 to 3.0% Mn, 0.2 to 2.0% Cr, and the balance substantial Fe. The slab having this compsn. is heated to 1000 to 1300°C and is subjected to rough rolling. The subsequent finish rolling is finished at 780 to 980°C. Next, it is cooled to form 620 to 780°C, is thereafter subjected to isothermal holding treatment for 1 to 10 sec or slow cooling treatment at ≤20°C/sec cooling rate and is subsequently cooled to from 350 to 500°C. Then, it is coiled round a coil and is thereafter cooled to 300°C at 10 to 100°C/hr cooling rate. In this way, the desired steel structure can be obtd.
Inventors:
Kazuya Miura
Masahiko Morita
Tetsuo Shimizu
Osamu Furu
Shusaku Takagi
Masahiko Morita
Tetsuo Shimizu
Osamu Furu
Shusaku Takagi
Application Number:
JP14684498A
Publication Date:
April 28, 2003
Filing Date:
May 28, 1998
Export Citation:
Assignee:
Kawasaki Steel Co., Ltd.
International Classes:
C21D8/04; C21D8/02; C21D9/46; C22C38/00; C22C38/38; (IPC1-7): C21D9/46; C21D8/02; C22C38/00; C22C38/38
Domestic Patent References:
| JP665677A | ||||
| JP4276025A | ||||
| JP6043430A |
Attorney, Agent or Firm:
Akihide Sugimura (8 outside)