Hypereutectoid rail and manufacturing method thereof

Abstract

The invention relates to the field of railway, and discloses a hypereutectoid rail and a manufacturing method thereof, which includes rolling a steel billet containing V and Ti, wherein, based on its total weight, the steel billet contains C of 0.85-0.94 wt %, and the relation between the start rolling temperature Tstart/final rolling temperature Tfinal and the content of V and the content of Ti satisfies the following formulas: Tstart=1100+a([V]+5[Ti]), Tfinal=750+b([V]+5[Ti]), wherein, 500≤a≤800, 300≤b≤500; based on its total weight, the steel billet contains V of 0.03-0.08 wt %, Ti of 0.011-0.02 wt %, and [V]+5[Ti]: 0.12-0.14 wt %. The hypereutectoid rail manufactured with the method has excellent comprehensive performance of strength and toughness.

1 . A manufacturing method for hypereutectoid rail, said method comprising rolling a steel billet containing V and Ti, wherein, based on a total weight of the steel billet, the steel billet contains C of 0.85-0.94 wt %, and a relationship between a start rolling temperature T start /a final rolling temperature T final  and a content of V and a content of Ti satisfies the following formulas:
   T start =1100 +a ([V]+5[Ti]),     T final =750 +b ([V]+5[Ti]),   wherein 500≤a≤800, 300≤b≤500; and   based on the total weight of the steel billet, the steel billet contains [V] of 0.03-0.08 wt %, [Ti] of 0.011-0.02 wt %, and [V]+5[Ti] of 0.12-0.14 wt %.   
     
     
         2 . The method according to  claim 1 , wherein, based on the total weight of the steel billet, the steel billet contains [V] of 0.045-0.055 wt %, [Ti] of 0.014-0.02 wt %, and [V]+5[Ti] of 0.12-0.13 wt %. 
     
     
         3 . The method according to  claim 1 , wherein, based on the total weight of the steel billet, the steel billet also contains Si of 0.4-0.9 wt %, Mn of 0.7-1.3 wt %, Cr of 0.2-0.6 wt %, P≤0.02 wt %, S≤0.008 wt % and N of 0.06-0.09 wt %. 
     
     
         4 . The method according to  claim 3 , wherein, based on the total weight of the steel billet, the steel billet contains Si of 0.55-0.65 wt %, Mn of 1.25-1.3 wt %, Cr of 0.4-0.55 wt %, P≤0.014 wt %, S≤0.005 wt % and N of 0.06-0.07 wt %. 
     
     
         5 . The method according to  claim 1 , wherein the method also comprises the following steps: carrying out rapid cooling for a railhead when a surface temperature of the railhead T surface  drops to 20-50° C. below the final rolling temperature T final  after the rolling; ending the rapid cooling and continuing air-cooling the rail to room temperature when the surface temperature of the railhead T surface  drops to 450-550° C. due to the rapid cooling process. 
     
     
         6 . The method according to  claim 5 , wherein a the cooling rate for the rapid cooling is 2-5° C./s. 
     
     
         7 . The method according to  claim 6 , wherein the cooling rate for the rapid cooling is 4.5-4.9° C./s. 
     
     
         8 . The method according to  claim 5 , wherein the method for the rapid cooling is to apply a cooling medium to a top surface of the railhead and two sides of the rail. 
     
     
         9 . The method according to  claim 8 , wherein the cooling medium is compressed air and/or a water-air spray mixture. 
     
     
         10 . A hypereutectoid rail manufactured with the method according to  claim 1 .