In the 1980's the Indian Railways imported 60Kg chrome manganese and 52Kg chrome vanadium rails for the Metro Railways, Suburban Railways and other heavy traffic sections. These rails are sensitive to heat as sudden cooling of the joint may result in cracks or fractures.
Thermit has developed techniques for welding the 110UTS alloy steel rails involving the following steps:
The welding operation is performed according to the SKV process till the trimming of excess metal.
Thereafter the joint and heat affected zones are covered by a special hood for 20 minutes so that the joint is cooled gradually.