Metal treatment – Stock – Ferrous
Reexamination Certificate
2011-07-05
2011-07-05
Yee, Deborah (Department: 1733)
Metal treatment
Stock
Ferrous
C148S333000, C148S584000, C148S581000, C148S654000
Reexamination Certificate
active
07972451
ABSTRACT:
The present invention is: a pearlitic steel rail excellent in wear resistance and ductility, characterized in that, in a steel rail having pearlite structure containing, in mass, 0.65 to 1.40% C, the number of the pearlite blocks having grain sizes in the range from 1 to 15 μm is 200 or more per 0.2 mm2of an observation field at least in a part of the region down to a depth of 10 mm from the surface of the corners and top of the head portion; and a method for producing a pearlitic steel rail excellent in wear resistance and ductility, characterized by, in the hot rolling of said steel rail, applying finish rolling so that the temperature of the rail surface may be in the range from 850° C. to 1,000° C. and the sectional area reduction ratio at the final pass may be 6% or more, and then applying accelerated cooling to the head portion of said rail at a cooling rate in the range from 1 to 30° C./sec. from the austenite temperature range to at least 550° C.
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Fujita Kazuo
Iwano Katsuya
Kobayashi Akira
Matsushita Koichiro
Morohoshi Takashi
Baker & Botts LLP
Nippon Steel Corporation
Yee Deborah
LandOfFree
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