Rail steel with an excellent combination of wear properties and rolling contact fatigue resistance
A high-strength pearlitic steel rail with an excellent combination of wear properties and rolling contact fatigue resistance wherein the steel has 0.88% to 0.95% carbon, 0.75% to 0.92% silicon, 0.80% to 0.95% manganese, 0.05% to 0.14% vanadium, up to 0.008% nitrogen, up to 0.030% phosphorus, 0.008 to 0.030% sulphur, at most 2.5 ppm hydrogen, at most 0.10% chromium, at most 0.010% aluminium, at most 20 ppm oxygen, the remainder being iron and unavoidable impurities.
1. A high-strength pearlitic steel rail with an excellent combination of wear properties and rolling contact fatigue resistance wherein the steel consists of
0.88% to 0.95% carbon,
0.75% to 0.95% silicon,
0.80% to 0.95% manganese,
0.08% to 0.14% vanadium,
0.003 to 0.005% nitrogen,
up to 0.030% phosphorus,
0.012% to 0.030% sulphur,
at most 2.5 ppm hydrogen,
at most 0.10% chromium,
at most 0.010% aluminium,
at most 20 ppm oxygen,
the remainder being iron and unavoidable impurities.
2. Pearlitic rail according to claim 1 , wherein carbon is 0.90% to 0.95%.
3. Pearlitic rail according to claim 1 , wherein vanadium is 0.08% to 0.12%.
4. Pearlitic rail according to claim 1 , wherein nitrogen is 0.003 to 0.0037%.
5. Pearlitic rail according to claim 4 , wherein vanadium is 0.08% to 0.12% and sulfur is 0.014 to 0.030%.
6. Pearlitic rail according to claim 1 , consisting of
0.90% to 0.95% carbon,
0.82% to 0.92% silicon,
0.80% to 0.95% manganese,
0.08% to 0.12% vanadium,
0.003 to 0.005% nitrogen,
at most 0.015% phosphorus,
0.012% to 0.030% sulphur,
at most 2 ppm hydrogen,
at most 0.10% chromium,
at most 0.004% aluminium,
at most 20 ppm oxygen,
the remainder consisting of iron and unavoidable impurities.
7. Pearlitic rail according to claim 1 , wherein manganese is 0.80% to 0.90%.
8. Pearlitic rail according to claim 1 , having an RCF resistance of at least 130,000 cycles to initiation under water lubricated twin disc testing conditions.
9. Pearlitic rail according to claim 1 , wherein the wear is lower than 40 mg/m of slip at a hardness between 320 and 350 HB, or lower than 20 mg/m of slip at a hardness above 350 HB.
10. Pearlitic rail according to claim 1 , wherein sulfur is at most 0.020%.
11. Pearlitic rail according to claim 1 , wherein vanadium is 0.10 to 0.12%.
12. Pearlitic rail according to claim 4 , wherein vanadium is 0.10 to 0.12%.
13. Pearlitic rail according to claim 1 , wherein the wear is lower than 40 mg/m of slip at a hardness between 320 and 350 HB.
14. Pearlitic rail according to claim 1 , wherein the wear is lower than 20 mg/m of slip at a hardness above 350 HB.
15. Pearlitic rail according to claim 1 , wherein the wear is lower than 10 mg/m of slip at a hardness above 350 HB.
16. Pearlitic rail according to claim 1 , wherein the impurities consist of:
at most 0.02% Mo,
at most 0.10% Ni,
at most 0.03% Sn,
at most 0.02% Sb,
at most 0.025% Ti,
at most 0.01% Nb.
17. Pearlitic rail according to claim 6 , wherein the impurities consist of:
at most 0.02% Mo,
at most 0.10% Ni,
at most 0.03% Sn,
at most 0.02% Sb,
at most 0.025% Ti,
at most 0.01% Nb.
18. Pearlitic rail according to claim 17 , wherein chromium is 0.02% to 0.04% and sulfur is 0.016% to 0.030%.
19. Pearlitic rail according to claim 17 , consisting of
0.90% to 0.92% carbon,
0.89% to 0.92% silicon,
0.80% to 0.85% manganese,
0.11% to 0.12% vanadium,
0.003 to 0.0037% nitrogen,
0.012 to 0.015% phosphorus,
0.012 to 0.030% sulfur,
at most 2 ppm hydrogen,
0.02% to 0.04% chromium,
at most 0.004% aluminium,
at most 20 ppm oxygen,
the remainder consisting of iron and unavoidable impurities.
20. Pearlitic rail according to claim 19 , wherein sulfur is 0.012% to 0.020%.