Elaboration of a technology of long rail lashes production without induction heat treatment application

Abstract

Welding butts of rail lashes after resistance butt-welding are subjected to heat treatment to eliminate heat-affected zones. At present facilities of induction heating are used in Russia for the heat treatment and compressed air as a quenching media. However, this method of quenching has significant drawbacks, including appearance of new heat-affected zones at the local heating of the welded butts, deterioration of the welded butts’ straightness after cooling. Shlatter Company proposed a solution of this problem by application of the process of resistance butt-welding by rails fusion. Theoretical calculations and laboratory studies of the thermal cycle of rail steel samples welding were made in the Siberian State Industrial University, which showed a principal possibility of this method application under industrial conditions. The method assumes after the welded butt settling and cooling to keep the preset temperature from the moment of its reaching by passing alternative electric current pulses through the welded butt. The temperature of exposure is selected based on obtaining necessary fine grain seam metal structure. The duration of exposure is determined by latency period of the structure formation and is controlled by the number of current pulses. The carried out industrial experiments at the МСР-6301 resistance butt welding machine resulted in determining parameters of cooling time after settling, heating and cooling after the heating, as well as the number of heating pulses. A method of resistance butt welding was tested, enabling to obtain the welded joint of details of the P65 ДТ350 category rail steel. The welded joint had mechanical properties exceeding technical requirements of СТО РЖД 1.08.002–2009 specifications.