Laser cladding high-performance maraging-steel coatings on bainitic cross wing rails assisted with in-situ induction heating: Microstructure and performance

Abstract

Railway crossing usually bears enormous impact force and rolling contact stress during service, resulting in various surface defects or even failure of the wing rail. Laser cladding (LC) maraging-steel coatings on the rail surface shows great potential for hardfacing or repairing the wing rail effectively. However, the performance of as-deposited coatings can hardly meet our expectations because the in-situ aging heat treatment (IAHT) effect during LC is too weak to trigger the precipitation effectively. In this paper, the LC technology assisted with in-situ induction heating (LC-IH) was proposed to prepare high-performance 18Ni300 coatings on the surface of bainitic wing rail, so as to make the precipitation much more sufficient. As a result, the bending strength and impact toughness of bainitic wing rail deposited with 18Ni300 coating by LC-IH are enhanced by 4.2% and 20.0%. Meanwhile, the wear resistance of the LC-IHed rail is enhanced to 3.3 times and 1.3 times as much as those of the untreated rail and LCed rail, respectively, while its plastic deformation and fatigue crack propagation depths are greatly decreased. The main mechanism is that the cumulative IAHT time during LC-IH process was prolonged by 15.8 times as much as that during LC process, making the nanoprecipitates precipitate much more effectively. Therefore, the LC-IH technology can prepare high-performance coatings in-situ without bulk heat treatment in the furnace, showing strong industrial potentials in the future.