NKK has developed high strength bainitic steel rails with superior flaking resistance for heavy haul railways. In this paper, rolling contact fatigue and wear behavior in bainitic and pearlitic rail steels with various tensile strengths were studied. Emphasis was placed on examining the formation behavior of the WEL (White Etching Layer) in bainitic and pearlitic steels, and its effect on flaking resistance. Advantages of the newly developed high-strength bainitic steel with superior flaking resistance, good wear resistance and excellent weldability have also been investigated. The bainitic steel rail showed higher values of yield strength, tensile strength, fatigue strength, elongation, rupture toughness at room temperature, and U-notch Charpy impact absorbed energy, compared to the heat-treated pearlitic steel rails. The wear resistance was similar in both rails. Flush butt-welded joint characteristics were also in very good condition. With a rolling contact fatigue-testing machine that can control the attack angle, the influence of attack angle on rolling contact fatigue life was investigated. Increase in the attack angle shortened the initiation time for flaking. Within the tested range, however, the bainitic steel rails showed at least twice the rolling contact fatigue life than that of the heat-treated pearlitic steel rails. The developed high strength bainitic steel rail has at least twice the rolling contact fatigue characteristics and almost equal wear resistance to those of the heat-treated pearlitic rail, thus the developed high strength bainitic steel rail is expected to provide excellent performance in heavy haul railways. (VDEh)
High strength bainitic steel rails for heavy haul railways with superior damage resistance
Hochfeste bainitische Schienenstähle mit verbesserter Flockenbeständigkeit für hochbelastete Schienenwege
NKK Technical Review ; 84 ; 44-51
2001
8 Seiten, 19 Bilder, 2 Tabellen, 11 Quellen
Article (Journal)
English
Bainitic rails for heavy haul operation
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