Cyclic plastic deformation and damage initiation of laser-cladded flange tip lift crossings in tramlines

Laser cladding presents a promising alternative to conventional arc welding for repairing damaged rails, particularly flange tip lift crossings (FTLCs) in tram systems. It offers significant improvements in mechanical properties compared to the parent rail material typically used for FTLCs. This study investigates the cyclic plastic deformation, i.e., ratcheting, and damage initiation life of laser-cladded FTLCs, supported by a calibrated cyclic plasticity model based on experimental ratcheting behavior of R260 rail steel and the laser cladding alloy Stellite 21. A cyclic rolling contact simulation was conducted, replicating wheelset-crossing interactions using repeated translations of non-Hertzian contact pressure distributions and longitudinal tangential traction on both the tangent track and ramp surfaces of FTLCs. Damage initiation life was estimated from the stabilized ratcheting strain rate and the local material ductility. The ramp section of the FTLCs was found to experience up to 2.6 times more ratcheting strain compared to the tangent section, leading to a significantly shorter damage initiation life. In this investigation, laser cladding was found to substantially enhance the damage initiation life, proving to be an effective repair and service-life extension method for both the tangent track and the ramp of FTLCs.