Metal treatment – Process of modifying or maintaining internal physical... – Heating or cooling of solid metal
Reexamination Certificate
2007-05-15
2007-05-15
Kastler, Scott (Department: 1742)
Metal treatment
Process of modifying or maintaining internal physical...
Heating or cooling of solid metal
C148S333000, C420S126000
Reexamination Certificate
active
10228802
ABSTRACT:
An improved steel railroad rail, and methods for producing same, having a carbon content in a range from 0.7 to 0.95 wt % and titanium in the range of 0.005 to 0.105 wt % is provided that has increased wear resistance and increased fracture toughness over conventional steel rail. The rail is characterized as having a pearlitic phase of an eutectoid nature. The average ultimate tensile strength is in a range from 178,000 to 207,000 psi, with a minimum of 174,000 psi. The average yield strength is in a range from 122,000 to 141,000 psi, with the minimum of 120,000 psi. The average percent elongation is in a range from 10.3 to 12.5, with a minimum of 10.00. The Brinell hardness on the surface at any position of the head top and upper gage corners of the rail is in a range from 370 to 420 BHN. The hardness 19 mm below the top surface is in a range from 360 to 405 BHN and 19 mm below the surface at the upper gage corners is in a range from 360 to 410 BHN. The characteristics of the steel rail produced in accordance with the present invention is a substantial improvement as compared with rail used today. The production of a fully pearlitic steel rail having a carbon content from 0.7 to 0.95 wt % and titanium in the range of 0.005 to 0.105 wt % Ti is remarkable and unexpected. A steel rail of this type having a hardness in a range from 370 to 420 BHN and a combination of yield strength, ultimate tensile strength, elongation and surface and in-depth Brinell hardness goes beyond all expectations and results in a superior and commercially important steel rail.
REFERENCES:
patent: 4913747 (1990-04-01), Fukuda et al.
patent: 5658400 (1997-08-01), Uchino et al.
patent: 5759299 (1998-06-01), Yokoyama et al.
patent: 5762723 (1998-06-01), Ueda et al.
patent: 5830286 (1998-11-01), Ueda et al.
patent: 401159327 (1989-06-01), None
patent: 345296 (2000-12-01), None
patent: 3140 (2001-01-01), None
English translation of Japanese patent 401159327A published Jun. 22, 1989, Kageyama et al.
CF&I Steel
Kastler Scott
Schwabe Williamson & Wyatt
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