Title:
PRODUCTION OF HOT ROLLED STEEL SHEET FOR WORKING EXCELLENT IN FATIGUE CHARACTERISTIC
Document Type and Number:
Japanese Patent JP3831146
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To improve both the fatigue characteristics and workability of the steel sheet by subjecting a slab having a specified compsn. to rough rolling, thereafter executing high pressure descaling, subjecting it to hot finish rolling under specified conditions, executing heating and cooling and forming its structure into a specified one.
SOLUTION: A slab composed of, by mass, 0.03 to 0.20% C, 0.1 to 1.4% Si, 0.5 to 3.0% Mn, ≤0.02% P, ≤0.01% S, 0.005 to 1.0% Al, 0.2 to 2.0% Cu, 0.0002 to 0.0020% B, and the balance Fe with inevitable impurities is subjected to rough rolling, is thereafter subjected to high pressure descaling and is subjected to hot finish rolling at ≥Ar3 point. Then, it is retained in a range from the Ar3 point to the Ar1 point for 1 to 10 sec, is thereafter cooled at ≥20°C/sec and is coiled at ≤350°C. As a result, the steel sheet whose microstructure is the composite one composed of ferrite as the main phase and martensite as a 2nd. phase, and in which Cu in the ferritic phase exists in the precipitated and/or solid solution state in which the size of particles composed of Cu alone is ≤2 nm can be obtd.
Inventors:
Tatsuo Yokoi
Hiroyuki Tanahashi
Manabu Takahashi
Hiroyuki Tanahashi
Manabu Takahashi
Application Number:
JP12541599A
Publication Date:
October 11, 2006
Filing Date:
May 06, 1999
Export Citation:
Assignee:
Nippon Steel Corporation
International Classes:
C21D8/04; C21D9/46; C22C38/00; C22C38/16; C22C38/58; (IPC1-7): C21D9/46; C21D8/04; C22C38/00; C22C38/16; C22C38/58
Domestic Patent References:
| JP11193443A | ||||
| JP5331591A | ||||
| JP9241793A | ||||
| JP8060240A | ||||
| JP9103817A |
Attorney, Agent or Firm:
Shiina Akira