Importance

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Abstract

Railroad rails having improved wear resistance, are produced by controlled forced cooling from above the austenite transformation temperature, to produce rails having a fine pearlite metallurgical structure in the head portions of the rails. Apparatus comprising a series of cooling headers utilizing a liquid cooling medium, such as unheated (i.e., cold, or ambient temperature) water, alternating with a series of air zones, is preferably arranged in line with the production rolling mill, to receive hot rails as they emerge from the mill, without the necessity of intervening reheating. A roller type restraint system transports the rails through the cooling apparatus, while restraining them in the appropriate position. Each segment of the rail length is intermittently subjected to forced cooling by spray application of the liquid cooling medium, applied to the head portion, and the central portion of the base bottom, of the rail, with means being provided to prevent spray from impinging on the web and base tips of the rail. During the intervals between applications of forced cooling, heat soaks back from the web portion of the rail, the operating parameters of the system being so arranged that the temperature of the rail remains essentially above the martensite formation temperature. A computerized control system discontinues the application of forced cooling, at a predetermined stop temperature, also above the martensite formation temperature. The apparatus and method are capable of producing rails having the desired fine pearlite structure in the head portion, on a consistent basis, notwithstanding wide variations in temperature between different rails, and different segments of the same rail, as they emerge from a conventional production rolling mill.

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First Claim