METHOD FOR THERMAL TREATMENT OF RAILS Russian patent published in 2013 - IPC C21D9/04 

FIELD: metallurgy.

SUBSTANCE: accelerated cooling is carried out upon completion of hot rolling with air or air with admixture of water along a head and a foot of a rail in two stages, first in the temperature range from ≥900°C to ≤870°C along the head with the cooling speed of 2-15°C/s, and along the foot with the speed of 1-10°C/s, and then in the temperature range from 870°C to 650°C and less along the head with the cooling speed of 2-20°C/s, and along the foot with the cooling speed of 1-15°C/s, at the same time in each specific case the cooling speed along the head differs from the cooling speed along the foot, and the total time of accelerated cooling makes 90-145 sec. Steel, if required, additionally contains one or more elements selected from the group including wt %: chrome from 0.04 to 1.10, vanadium from 0.03 to 0.09, nitrogen from 0.007 to 0.020, niobium from 0.001 to 0.06.

EFFECT: provision of balanced complex of mechanical properties of rails from carbon and low-alloyed steel, reduced curvature of rails in the vertical plane, reduction of forces during cold straightening to the minimum and provision of minimum residual stresses of a rail with length of 100-200 m.

2 cl, 4 tbl