Method for thermal treatment of pearlitic rail steels

摘要

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 austenitization temperature of about 950 DEG to 1050 DEG 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 s to 650 DEG to 600 DEG 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 DEG 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 DEG to 650 DEG C. and then rapidly cooled by means of water or other appropriate quenching media to a temperature of less than 100 DEG C.