Method for heat-treating bainite steel rail

Abstract

A method for heat-treating a bainite steel rail is disclosed. The method includes: cooling a rolled steel rail naturally to lower a surface temperature of a rail head of the steel rail to 460° C. −490° C.; cooling the steel rail forcely at a cooling rate of 2.0° C./s-4.0° C./s to lower the surface temperature of the rail head to 250° C.-290° C.; placing the steel rail in an ambient temperature until the surface temperature of the rail head is more than 300° C.; performing a tempering on the steel rail in a heating furnace at 300° C.-350° C. for 2 h-6 h; and air cooling the steel rail to the ambient temperature. Steel rails heat-treated by present method may have a stable retained austenite structure and a good mechanical performance.

What is claimed: 
     
         1 . A method for heat-treating a bainite steel rail, comprising:
 cooling a rolled steel rail naturally to lower a surface temperature of a rail head of the steel rail to 460° C.-490° C.;   cooling the steel rail forcely at a cooling rate of 2.0° C./s-4.0° C./s to lower the surface temperature of the rail head to 250° C.-290° C.;   placing the steel rail in an ambient temperature until the surface temperature of the rail head is more than 300° C.;   performing a tempering on the steel rail in a heating furnace at 300° C.-350° C. for 2 h-6 h; and   air cooling the steel rail to the ambient temperature.   
     
     
         2 . The method for heat-treating the bainite steel rail of  claim 1 , wherein, cooling the steel rail forcely is performed by applying a cooling medium onto the rail head. 
     
     
         3 . The method for heat-treating the bainite steel rail of  claim 2 , wherein, the cooling medium includes an air-water gas or a compressed air.