Effects of Two Laser Cladding Coatings on Wear and Damage Properties of Wheel/Rail Materials

Co-based alloy powders and Fe-based alloy powders were chosen to perform laser cladding on the wheel/rail materials through a CO₂ multimode laser. The microstructures, compositions, hardness and stress states of the Co-based alloy and Fe-based alloy cladding layers were analyzed. The residual stress on the surface of untreated specimen was tensile stress, and the residual stresses on surfaces of the laser cladding coatings were compressive stress. The rolling friction and wear tests were carried out with the untreated and laser treated wheel/rail specimens on the MJP-30A rolling contact fatigue testing machine. The results showed that the wear rates of wheel/rail specimens were obviously reduced after laser cladding. The wear rates of wheel and rail specimens with Co-based alloy coating were decreased by 96.7% and 98.9%, respectively, and the wear rates of wheel and rail specimens with Fe-based alloy coating were decreased by 81.7% and 93.5%, respectively. The untreated wheel/rail specimens showed fatigue damage. The Co-based alloy coating was damaged the most slightly, the worn surface was smooth with slight flaking. The Fe-based alloy coating showed tiny cracks and furrows.