Process for manufacturing high-strength bainitic steel rails with excellent rolling-contact fatigue resistance

摘要

A process for manufacturing high-strength bainitic steel rails with an excellent rolling-contact fatigue resistance comprising the steps of hot rolling steel containing 0.15% to 0.45% carbon, 0.15% to 2.00% silicon, 0. 30% to 2.00% manganese, 0.50% to 3.00% chromium, and at least one element selected from a group of molybdenum, nickel, copper, niobium, vanadium, titanium and boron, subjecting the hot-rolled rail to an accelerated cooling from the austenite region to a temperature between 500° to 300° C., at which the accelerated cooling is stopped, at a rate of 1° to 10° C. per second, and then further cooling the rail to a lower temperature by natural or controlled cooling. The obtained rail exhibits a hardness of Hv 300 to 400 in the center of the rail head surface of the head and not lower than Hv 350 in the gage corner, and the hardness of the gage corner is higher than that of the center of the rail head surface by Hv 30 or more.