Q. Explain Flash Butt welding?
In this process the ends of two rails are kept at fixed distance apart and a mould (designed to suit the rail section ) is fitted on. The rail ends are then heated to yellow red temperature with a blowlamp. A swiveling type crucible containing iron oxide and aluminum powder to match the metallurgical composition of the rails is then ignited and the molten metal is poured into the mould so that the gap between the rail ends is filled up with over flow on all sides. The mould is then removed and excess metal is chipped off from the railhead while still hot. Later it is filed to railhead profile.
Normally it takes 45 minutes to weld a joint but by quick thermit process it can be done in 15 minutes. The joint can be brought into use immediately after welding.