High-impact-toughness steel rail and production method thereof

Abstract

The invention relates to a high-impact-toughness steel rail and a production method thereof, and belongs to the field of steel rail material production. The present invention is to provide a high-impact-toughness steel rail. The high-impact-toughness steel rail provided in the present invention is a pearlite steel rail with 0.05˜0.09 μm of inter-lamellar spacing and 30˜35 J of ballistic work at normal temperature; the chemical components of the steel rail in weight percentage are: C: 0.71-0.82 wt %, Si: 0.25-0.45 wt %, Mn: 0.75-1.05 wt %, V: 0.03-0.15 wt %, P: ≦0.030 wt %, S: ≦0.035 wt %, Al: ≦0.020 wt %, and Fe and inevitable impurities of the remaining content. The U-type impact toughness of rail head of the steel rail manufactured with the method disclosed in the present invention can be 30 J or more, and the tensile strength is about 1,300 MPa or higher.

1 . A high-impact-toughness steel rail, belonging to a pearlite steel rail, with 0.05˜0.09 μm of inter-lamellar spacing and 30˜35 J of ballistic work at normal temperature;
 the chemical components of the steel rail in weight percentage are: C: 0.71˜0.82 wt %, Si: 0.25˜0.45 wt %, Mn: 0.75˜1.05 wt %, V: 0.03˜0.15 wt %, P: ≦0.030 wt %, S: ≦0.035 wt %, Al: ≦0.040 wt %, and Fe and inevitable impurities of the remaining content. 
 
     
     
         2 . The high-impact-toughness steel rail according to  claim 1 , wherein the chemical components of the steel rail in weight percentage are: C: 0.71˜0.82 wt %, Si: 0.25˜0.45 wt %, Mn: 0.75˜1.05 wt %, V: 0.03˜0.15 wt %, P: ≦0.030 wt %, S: ≦0.035 wt %, Al: ≦0.020 wt %, and Fe and inevitable impurities of the remaining content. 
     
     
         3 . The high-impact-toughness steel rail according to  claim 1 , wherein the chemical components of the steel rail in weight percentage are: C: 0.72˜0.76 wt %, Si: 0.35˜0.37 wt %, Mn: 0.95˜0.99 wt %, V: 0.05˜0.09 wt %, P: ≦0.012 wt %, S: ≦0.011 wt %, Al: ≦0.04 wt %, and Fe and inevitable impurities of the remaining content. 
     
     
         4 . The high-impact-toughness steel rail according to  claim 1 , wherein the mechanical properties of the steel rail are: Rp0.2: 800˜860 MPa, Rm: 1,300˜1,350 MPa, A: 13˜15%, Z: 31˜35%. 
     
     
         5 . The high-impact-toughness steel rail according to  claim 2 , wherein the mechanical properties of the steel rail are: Rp0.2: 800˜860 MPa, Rm: 1,300˜1,350 MPa, A: 13˜15%, Z: 31˜35%. 
     
     
         6 . The high-impact-toughness steel rail according to  claim 3 , wherein the mechanical properties of the steel rail are: Rp0.2: 800˜860 MPa, Rm: 1,300˜1,350 MPa, A: 13˜15%, Z: 31˜35%. 
     
     
         7 . A method for producing the high-impact-toughness steel rail according to  claim 1 , comprising steelmaking, casting, rolling, and post-rolling heat treatment, wherein, the post-rolling heat treatment comprises the following steps:
 a. accelerated cooling: applying a cooling medium to rail head tread, two sides of rail head, and central part of rail base of the rolled steel rail for accelerated cooling at 1.0˜5.0° C./s cooling rate, wherein, the temperature at the central part of rail head tread, two sides of rail head, and central part of rail base of the rolled steel rail is 650˜900° C.;   b. air cooling: stopping the accelerated cooling when the temperature at the rail head tread drops to 400˜550° C., and cooling the steel rail by air cooling to room temperature, to obtain a pearlite steel rail with 0.05˜0.09 μm of inter-lamellar spacing.   
     
     
         8 . The method for producing the high-impact-toughness steel rail according to  claim 7 , wherein the chemical components of the steel rail in weight percentage are: C: 0.72˜0.76 wt %, Si: 0.35˜0.37 wt %, Mn: 0.95˜0.99 wt %, V: 0.05˜0.09 wt %, P: ≦0.012 wt %, S: ≦0.011 wt %, Al: ≦0.04 wt %, and Fe and inevitable impurities of the remaining content. 
     
     
         9 . The method for producing the high-impact-toughness steel rail according to  claim 7 , wherein in the steelmaking procedure, low-sulfur molten iron is charged into a steelmaking furnace while adding a high-alkalinity refining slag, and blind coal and a low-nitrogen alloy are used as a carburant for steelmaking. 
     
     
         10 . The method for producing the high-impact-toughness steel rail according to  claim 8 , wherein in the steelmaking procedure, low-sulfur molten iron is charged into a steelmaking furnace while adding a high-alkalinity refining slag, and blind coal and a low-nitrogen alloy are used as a carburant for steelmaking. 
     
     
         11 . The method for producing the high-impact-toughness steel rail according to  claim 7 , wherein the steelmaking procedure comprises smelting in a convertor or electric furnace, refining in a LF furnace, and RH or VD vacuum treatment, wherein, a foaming agent is used in a heating process during the refining in the LF furnace. 
     
     
         12 . The method for producing the high-impact-toughness steel rail according to  claim 9 , wherein the steelmaking procedure comprises smelting in a convertor or electric furnace, refining in a LF furnace, and RH or VD vacuum treatment, wherein, a foaming agent is used in a heating process during the refining in the LF furnace. 
     
     
         13 . The method for producing the high-impact-toughness steel rail according to  claim 10 , wherein the steelmaking procedure comprises smelting in a convertor or electric furnace, refining in a LF furnace, and RH or VD vacuum treatment, wherein, a foaming agent is used in a heating process during the refining in the LF furnace. 
     
     
         14 . The method for producing the high-impact-toughness steel rail according to  claim 7 , wherein the casting procedure is an overall-protection casting, and the steel billet is subjected to a slow cooling after casting. 
     
     
         15 . The method for producing the high-impact-toughness steel rail according to  claim 13 , wherein the casting procedure is an overall-protection casting, and the steel billet is subjected to a slow cooling after casting. 
     
     
         16 . The method for producing the high-impact-toughness steel rail according to  claim 7 , wherein after slow cooling, steel billet is heated up for austenization before rolling, and the tapping temperature after the heating process is 1,000° C. 
     
     
         17 . The method for producing the high-impact-toughness steel rail according to  claim 15 , wherein after slow cooling, steel billet is heated up for austenization before rolling, and the tapping temperature after the heating process is 1,000° C. 
     
     
         18 . The method for producing the high-impact-toughness steel rail according to  claim 7 , wherein the cooling medium is compressed air or a water mist-air mixture. 
     
     
         19 . The method for producing the high-impact-toughness steel rail according to  claim 15 , wherein the cooling medium is compressed air or a water mist-air mixture. 
     
     
         20 . The method for producing the high-impact-toughness steel rail according to  claim 17 , wherein the cooling medium is compressed air or a water mist-air mixture.