Pearlitic steel rail with high strength and toughness and producing method thereof

Abstract

A pearlitic steel rail with high strength and toughness and a producing method thereof. The producing method comprises: controlling the following processing conditions in a rolling procedure to produce the pearlitic steel rail with high strength and toughness: initial rolling temperature of 1,120-1,180° C., final rolling temperature of 840-880° C., rail profile reduction in last two rolling passes of 6%-12%; the steel rail is cooled to 600° C. or lower at a cooling rate ≦2.0° C./s after final rolling, and then air-cooled to room temperature; the chemical composition of the steel rail meets the following requirements: C: 0.75%-0.84%, Si: 0.30%-0.80%, Mn: 0.50%-1.50%, V: 0.04%-0.12%, Ti: 0.004%-0.02%, and 0.10%≦V+10Ti≦0.25%, [N]≦30 ppm, P≦0.020%, S≦0.008%, with the remaining content consisting of Fe and inevitable impurities.

What is claimed is: 
     
         1 . A pearlitic steel rail with high strength and toughness, wherein the chemical composition of the steel rail meet the following requirements: C: 0.75%-0.84%, Si: 0.30%-0.80%, Mn: 0.50%-1.50%, V: 0.04%-0.12%, Ti: 0.004%-0.02%, and 0.10%≦V+10Ti≦0.25%, [N]≦30 ppm, P≦0.020%, S≦0.008%, with the remaining content consisting of Fe and inevitable impurities;
 and the following processing conditions are controlled in the rolling procedure to produce the pearlitic steel rail with high strength and toughness: initial rolling temperature of 1,120-1,180° C., final rolling temperature of 840-880° C., and rail profile reduction in last two rolling passes of 6%-12%; the steel rail is cooled to 600° C. or lower at a cooling rate ≦2.0° C./s after final rolling, and then air-cooled to room temperature. 
 
     
     
         2 . The pearlitic steel rail with high strength and toughness according to  claim 1 , wherein the steel rail is cooled to 600° C. or lower at a cooling rate ≦2.0° C./s after final rolling, by using compressed air as cooling medium. 
     
     
         3 . The pearlitic steel rail with high strength and toughness according to  claim 1 , wherein the steel rail is cooled to 600° C. or lower at a cooling rate ≦2.0° C./s after final rolling by holding it in a cooling bed. 
     
     
         4 . The pearlitic steel rail with high strength and toughness according to  claim 2 , wherein the steel rail is cooled to 600° C. or lower at a cooling rate ≦2.0° C./s after final rolling by holding it in a cooling bed. 
     
     
         5 . A producing method of a pearlitic steel rail with high strength and toughness, comprising: controlling the following processing conditions in a rolling procedure to produce the pearlitic steel rail with high strength and toughness: initial rolling temperature of 1,120-1,180° C., final rolling temperature of 840-880° C., rail profile reduction in last two rolling passes of 6%-12%; the steel rail is cooled to 600° C. or lower at a cooling rate ≦2.0° C./s after final rolling, and then air-cooled to room temperature;
 wherein the chemical composition of the steel rail meets the following requirements: C: 0.75%-0.84%, Si: 0.30%-0.80%, Mn: 0.50%-1.50%, V: 0.04%-0.12%, Ti: 0.004%-0.02%, and 0.10%≦V+10Ti≦0.25%, [N]≦30 ppm, P≦0.020%, S≦0.008%, with the remaining content consisting of Fe and inevitable impurities. 
 
     
     
         6 . The producing method according to  claim 5 , wherein the steel rail is cooled to 600° C. or lower at a cooling rate ≦2.0° C./s after final rolling, by using compressed air as cooling medium. 
     
     
         7 . The producing method according to  claim 5 , wherein the steel rail is cooled to 600° C. or lower at a cooling rate ≦2.0° C./s after final rolling by holding it in a cooling bed. 
     
     
         8 . The producing method according to  claim 6 , wherein the steel rail is cooled to 600° C. or lower at a cooling rate ≦2.0° C./s after final rolling by holding it in a cooling bed.