Effect of the angle of attack on flaking behavior in pearlitic and bainitic steel rails

Rolling contact fatigue (RCF) behavior in pearlitic and bainitic rail steels with various angles of attack has been investigated by the twin-disk type RCF test machine, in which the angle of attack can be controlled. The materials studied were a standard carbon rail steel with Vickers hardness of 270 (270 HV), a head hardened premium pearlitic rail steel with 390 HV, a bainitic rail steel of 270 HV and a high strength bainitic rail steel of 420 HV. The initiation time for RCF damage decreased with an increase in the angle of attack for all the steels tested. Bainitic rail steels showed better RCF damage resistance than pearlitic rail steels at any angle of attack. Even the low strength bainitic rail steel showed higher RCF resistance than the head hardened pearlitic rail steel. The effect of angle of attack on wear in various rail steels was also examined. Metallurgical and mechanical factors influencing RCF behavior have been discussed.