High-carbon and high-strength and toughness pearlitic rail and manufacturing method thereof

Abstract

In view of the problem of uneven performance of railhead sections of pearlitic rail manufactured with existing technique and the poor performance of the pearlitic rail obtained, the invention provides a manufacturing method for high-carbon and high-strength and toughness pearlitic rail, including the following steps to: a. hot roll the steel billet into rail, with a final rolling temperature of 900-1000° C.; b. blow a cooling medium to the top surface of railhead, wherein, the two sides of railhead and the lower jaws on two sides of railhead when the center of top surface of rail is air-cooled to 800-850° C.; then air-cool the rail to room temperature after the center of top surface of rail is cooled to 480-530° C. By controlling the composition of steel and adopting a two-stage accelerated cooling, a high-carbon rail is produced with better strength and excellent toughness which is suitable for heavy-haul railway.

What is claimed is: 
     
         1 . A manufacturing method for high-carbon and high-strength and toughness pearlitic rail, said manufacturing method comprising the following sequential steps:
 (a) hot rolling a steel billet to form the rail with a final rolling temperature range of 900-1000° C.;   (b) air cooling the rail until a center of a top surface of a railhead of the rail is cooled to 800-850° C.;   (c) blowing a cooling medium to the top surface of the railhead of the rail, two sides of the railhead and lower jaws on the two sides of the railhead until the center of the top surface of the railhead of the rail is cooled to 480-530° C.; and   (d) further air cooling the rail to room temperature.   
     
     
         2 . The manufacturing method according to  claim 1 , wherein the rail comprises:
 (i) 0.86 wt. % to 1.05 wt. % C;   (ii) 0.20 wt. % to 0.50 wt. % Si;   (iii) 0.50 wt. % to 0.95 wt. % Mn;   (iv) 0.20 wt. % to 0.40 wt. % Cr;   (v) at least one of 0.02 wt. % to 0.10 wt. % V, 0.001 wt. % to 0.030 wt. % Ti and 0.005 wt. % to 0.08 wt. % Nb; and   (vi) Fe.   
     
     
         3 . The manufacturing method according to  claim 1 , wherein the cooling medium is at least one of compressed air and a water-air spray mixture. 
     
     
         4 . The manufacturing method according to  claim 1 , wherein a cooling rate in step (c) is 2.0-5.0° C./s. 
     
     
         5 . A high-carbon and high-strength and toughness pearlitic rail manufactured by the manufacturing method according to  claim 1 , wherein the rail comprises:
 (i) 0.86 wt. % to 1.05 wt. % C;   (ii) 0.20 wt. % to 0.50 wt. % Si;   (iii) 0.50 wt. % to 0.95 wt. % Mn;   (iv) 0.20 wt. % to 0.40 wt. % Cr;   (v) at least one of 0.02 wt. % to 0.10 wt. % V, 0.001 wt. % to 0.030 wt. % Ti and 0.005 wt. % to 0.08 wt. % Nb; and   (vi) Fe.