METHOD FOR PEARLITIC RAIL STEELS

摘要

METHOD FOR PEARLITIC RAIL STEELS The present invention relates to a method for thermal treatment of pearlitic rail steel. For increasing strength and wear resistance steels with the claimed composition are produced with a fine lamellar pearlite structure by heat treatment. During the first cycle the rail head portion is heated in a sufficient depth of up to 50 mm by means of a burner or an inductive system to an austenitisation temperature of about 950 to 1050.degree.C. Thereafter the heated head portion is cooled by means of compressed air in such a way that in a first step by blowing a large amount of air the temperature of the rail head portion is cooled within 10 to 20 seconds to 650 to 600.degree.C. before the area of the pearlitic transformation. In a second step with throttled blowing compared to the first step in the area of the pearlitic transformation the rail head portion is cooled within 2 to 4 minutes to about 400.degree.C until finishing the pearlitic transformation. Then the rail head portion is again heated for 4 to 6 minutes to a temperature of about 600 to 650.degree.C and then rapidly cooled by means of water or other appropriate quenching media to a temperature of less than 100 .degree.C .