Metal treatment – Stock – Ferrous
Reexamination Certificate
2005-06-07
2005-06-07
Yee, Deborah (Department: 1742)
Metal treatment
Stock
Ferrous
C148S333000, C148S334000, C148S602000, C148S603000, C148S652000, C148S330000, C148S332000
Reexamination Certificate
active
06902632
ABSTRACT:
The present invention presents a high tensile strength cold rolled steel sheet having excellent formability, impact resistance and strain age hardening characteristics, and the production thereof. As a specific means, a slab having a composition which contains, by mass %, 0.15% or less of C, 0.02% or less of Al, and 0.0050 to 0.0250% of N at N/Al of 0.3 or higher, and has N in a solid solution state at 0.0010% or more, is first hot rolled at the finish rolling delivery-side temperature of 800° C. or above, and is subsequently coiled at the coiling temperature of 750° C. or below to prepare a hot rolled plate. Then, after cold rolling, the hot rolled plate is continuously cooled at a temperature from the recrystallization temperature to 900° C. at a holding time of 10 to 120 seconds, and is cooled by primary cooling in which the hot rolled plate is cooled to 500° C. or below at a cooling rate of 10 to 300° C./s, and furthermore if necessary, by secondary cooling in which a residence time is 300 seconds or less in a temperature range of the primary cooling stopping temperature or below and 350° C. or higher. Provided is a steel sheet containing a ferritic phase having an average crystal grain size of 10 μm or less at an area ratio of 50% or more, and if necessary, a martensitic phase at an area ratio of 3% or more as a second phase.
REFERENCES:
patent: 3673009 (1972-06-01), Levy
patent: 5123969 (1992-06-01), Chou
patent: 0 429 094 (1991-05-01), None
patent: 0 608 430 (1994-08-01), None
patent: 0943696 (1999-09-01), None
patent: 0 999 288 (2000-05-01), None
patent: 58 003922 (1983-03-01), None
patent: 60 052528 (1985-07-01), None
patent: 60 145355 (1985-12-01), None
patent: 61272323 (1986-12-01), None
patent: 04074824 (1992-03-01), None
patent: 6-116682 (1994-04-01), None
patent: 0 612 857 (1994-08-01), None
patent: 07 090482 (1995-08-01), None
patent: 8-35039 (1996-02-01), None
patent: 08 035039 (1996-06-01), None
patent: 08 325670 (1997-04-01), None
patent: 9-296252 (1997-11-01), None
patent: 11-80919 (1999-03-01), None
patent: 55 141526 (2001-01-01), None
Ishikawa Takashi
Kami Chikara
Kaneko Shinjiro
Okuda Kaneharu
Osawa Kazunori
DLA Piper Rudnick Gray Cary US LLP
JFE Steel Corporation
Yee Deborah
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