As carriage wheels run on a railway line it creates stress patterns within the rail, which leads to surface defects and reduces the service life of the rail. Corus has developed a technique which employs open arc welding to treat the affected zone and which it said was particularly cost effective. The strength of the technique lies in the replacement of those aspects of the conventional Manual Metal Arc (MMA) process that can result in variability in the quality of the repair with automatic and more controlled operations. The following factors contribute to the cost effectiveness and technical robustness of the new process: 1) a move away from the conventional preheating temperature of 350 deg C to just 80 deg C has the advantage of faster repair, reduced depth of heat affected zone, and more robust microstructure; 2) the use of standardised removal of the defect area by controlled milling has the advantage of reproducibility and removes the subjective judgement of the operator; 3) the use of a semi-automatic programmed open arc welding process with flux cored arc wire ensures control of heat input and predictable operational times. The quality of the weld restored running surface from the developed process is ensured as the repair is extremely resistant to fatigue and has similar wear resistance to that of the standard Grade R260 rail with uniform hardness and microstructures across the weld restored area. A comparative evaluation of the existing MMA technique and the new process was achieved by recording the thermal history of both processes using embedded thermocouples.
Rail weld repair technique helps save costs
Neue Technik zur Reparatur von Schienenschweißungen hilft Kosten zu senken
Steel Times International ; 34 , 4 ; 28-30
2010
2 Seiten, 4 Bilder
Article (Journal)
English
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