摘要:
An object is to provide a method for manufacturing a high-hardness and high-quality rail through a simple cooling process even in the presence of temperature variations in the longitudinal direction of the rail before the start of cooling. A rail manufacturing method includes a step of accelerated cooling a rail having a temperature equal to or higher than an austenite region temperature. In the rail manufacturing method, austenite represents a portion of a region from a cooled surface of a rail head to a depth of 5 mm at the end of accelerated cooling, and the temperature of a rail head surface at the completion of heat recuperation after the end of accelerated cooling is in a pearlite transformation temperature range.
摘要:
In the present invention, when a cooling apparatus (2) having a plurality of cooling sections (head section-cooling headers (21a) to (21c), and a foot section-cooling header (22)) disposed side by side in the longitudinal direction of the steel material cools a steel material hot worked or cooled/reheated, the steel material is conveyed at the conveyance distance L o (m) satisfying Equation (1), in the longitudinal direction of the steel material, in the cooling apparatus (2). In Equation (1), L o represents the conveyance distance (m) of the steel material, m represents a natural number, and L h represents the length (m) of the cooling sections in the longitudinal direction of the steel material. m − 0.20 × L h ≤ L o ≤ m + 0.20 × L h
摘要:
There is provided a manufacturing method and a manufacturing apparatus for a head hardened rail to which various alloy elements are added and which is excellent in hardness and toughness of a head portion surface layer. The method includes, when forcibly cooling at least a head portion of a hot-rolled rail (1) or a heated rail (1), starting the forcible cooling from a state where a surface temperature of the head portion (1a) of the rail (1) is not less than an austenite range temperature, and performing the forcible cooling at a cooling rate of 10°C/sec or more until the surface temperature reaches 500°C or more and 700°C or less after the forcible cooling is started.