The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Jan. 22, 1980

Filed:

Jul. 11, 1978
Applicant:
Inventors:

Chiaki Ouchi, Yokohama, JP;

Tomoyoshi Okita, Yokohama, JP;

Kazuaki Matsumoto, Yokohama, JP;

Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C21D / ;
U.S. Cl.
CPC ...
148 / ; 148 124 ; 148 36 ;
Abstract

A steel slab or bloom containing 0.3.about.0.15% by weight of C, 0.05.about.0.60% by weight of Si, 0.60.about.2.5% by weight of Mn, 0.010.about.0.15% by weight of Nb, 0.005.about.0.10% by weight of soluble Al and the remainder of iron is heated to such a temperature region above 1050.degree. C. and below the reheating temperature where the austenitic grain size would be 150.mu.. The heated slab or bloom is then hot rolled with total rolling reduction of more than 40% with respect to a finished thickness at the non-recrystallized austenitic region and the hot rolled stocks are subjected to accelerated cooling at a rate of 5.degree..about.20.degree. C./sec. from a temperature higher than the Ar.sub.3 transformation point to a temperature within 550.degree..about.650.degree. C. Finally the stocks are air cooled.


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