Rail and method for manufacturing same

Abstract

Provided is a rail that exhibits excellent wear resistance and reduced hardness variation in a rail length direction. The rail has a chemical composition containing 0.60% to 1.0% of C, 0.1% to 1.5% of Si, 0.01% to 1.5% of Mn, 0.035% or less of P, 0.030% or less of S, and 0.1% to 2.0% of Cr, the balance being Fe and incidental impurities. Surface hardness of the rail exhibits variation of ±HB 15 points or less in the rail length direction.

1 . A rail comprising
 a chemical composition containing, in mass %:   0.60% to 1.0% of C;   0.1% to 1.5% of Si;   0.01% to 1.5% of Mn;   0.035% or less of P;   0.030% or less of S; and   0.1% to 2.0% of Cr,   the balance being Fe and incidental impurities, wherein   surface hardness of a head of the rail exhibits variation of ±HB 15 points or less in a length direction of the rail.   
     
     
         2 . The rail of  claim 1 , wherein
 the chemical composition further contains, in mass %, one or more of:   1.0% or less of Cu;   0.5% or less of Ni;   0.5% or less of Mo; and   0.15% or less of V.   
     
     
         3 . The rail of  claim 1 , wherein
 the surface hardness of the head of the rail is HB 400 or greater.   
     
     
         4 . The rail of  claim 1 , wherein
 the variation of the surface hardness is ±HB 10 points or less.   
     
     
         5 . A rail manufacturing method comprising:
 heating to 1200° C. or higher, a steel raw material having a chemical composition containing, in mass %:   0.60% to 1.0% of C,   0.1% to 1.5% of Si,   0.01% to 1.5% of Mn,   0.035% or less of P,   0.030% or less of 5, and   0.1% to 2.0% of Cr,   the balance being Fe and incidental impurities;   hot rolling the steel raw material after the heating, the hot rolling being performed such that rolling in a rail length direction in a temperature region not exceeding 1000° C. is performed over a plurality of passes with a time interval between passes exhibiting variation of 15 s or less in the rail length direction, a cumulative area reduction rate of 40% or greater for a portion forming a rail head, and a finisher delivery temperature of 900° C. or higher; and   cooling the rail head after the hot rolling from a cooling start temperature of 800° C. or higher to a cooling stop temperature of 600° C. or lower at a cooling rate of 1° C./s to 10° C./s.   
     
     
         6 . The rail manufacturing method of  claim 5 , wherein
 the chemical composition further contains, in mass %, one or more of:   1.0% or less of Cu;   0.5% or less of Ni;   0.5% or less of Mo; and   0.15% or less of V.   
     
     
         7 . The rail manufacturing method of  claim 5 , wherein
 the cooling rate in the cooling exhibits variation of ±1° C./s or less in the rail length direction.   
     
     
         8 . The rail of  claim 2 , wherein
 the surface hardness of the head of the rail is HB 400 or greater.   
     
     
         9 . The rail of  claim 2 , wherein
 the variation of the surface hardness is ±HB 10 points or less.   
     
     
         10 . The rail of  claim 3 , wherein
 the variation of the surface hardness is ±HB 10 points or less.   
     
     
         11 . The rail manufacturing method of  claim 6 , wherein
 the cooling rate in the cooling exhibits variation of ±1° C./s or less in the rail length direction.