Rail and method for producing same

Abstract

A rail exhibits a high 0.2% proof stress after shipping, which is effective for improving rolling contact fatigue resistance of the rail, the rail having a chemical composition containing C: 0.70% to 0.85%, Si: 0.1% to 1.5%, Mn: 0.4% to 1.5%, P: 0.035% or less, S: 0.010% or less, and Cr: 0.05% to 1.50%, with the balance being Fe and inevitable impurities, and exhibiting, at least 90 days after a preparation date of a steel material inspection certificate of the rail which describes at least a measurement result of a 0.2% proof stress of a head of the rail, an improvement margin of a 0.2% proof stress of 40 MPa or more, relative to the 0.2% proof stress described in the steel material inspection certificate.

1 . A rail accompanied by a steel material inspection certificate which describes at least a measurement result of a 0.2% proof stress of a head of the rail, having a chemical composition containing, in mass%,
 C: 0.70% to 0.85%,   Si: 0.1% to 1.5%,   Mn: 0.4% to 1.5%,   P: 0.035% or less,   S: 0.010% or less, and   Cr: 0.05% to 1.50%, with the balance being Fe and inevitable impurities,   wherein the rail exhibits, at least 90 days after a preparation date of the steel material inspection certificate, an improvement margin of a 0.2% proof stress of 40 MPa or more, relative to the 0.2% proof stress described in the steel material inspection certificate.   
     
     
         2 . The rail according to  claim 1 , wherein the chemical composition further contains, in mass%, at least one selected from the group consisting of
 V: 0.30% or less,   Cu: 1.0% or less,   Ni: 1.0% or less,   Nb: 0.05% or less,   Mo: 0.5% or less,   Al: 0.07% or less,   W: 1.0% or less,   B: 0.005% or less, and   Ti: 0.05% or less.   
     
     
         3 . A method for producing a rail, comprising:
 hot rolling a steel raw material to obtain a rail, the steel raw material having a chemical composition containing, in mass %,
 C: 0.70% to 0.85%, 
 Si: 0.1% to 1.5%, 
 Mn: 0.4% to 1.5%, 
 P: 0.035% or less, 
 S: 0.010% or less, and 
 Cr: 0.05% to 1.50%, with the balance being Fe and inevitable impurities; 
   straightening the rail with a load of 100 tf or more; and   preparing a steel material inspection certificate including at least a measurement result of a 0.2% proof stress of a head of the rail within 480 hours after the straightening.   
     
     
         4 . The method according to  claim 3 , wherein the chemical composition further contains, in mass%, at least one selected from the group consisting of
 V: 0.30% or less,   Cu: 1.0% or less,   Ni: 1.0% or less,   Nb: 0.05% or less,   Mo: 0.5% or less,   Al: 0.07% or less,   W: 1.0% or less,   B: 0.005% or less, and   Ti: 0.05% or less.