Microstructure and wear resistance of laser cladding particulate reinforced Fe-based composite coating on railway steel

Abstract

It has been proved that the laser cladding particulate reinforced metal-based composite coating is of great benefit to industrial applications, owing to its superior properties such as wear resistance, corrosion resistance, and metallurgical bond with a base metal. It is also well-known that the railway switch can easily get damaged due to the abominable conditions of high speed and heavy haul in the rail-wheel mechanical system, and it can cause quite huge loss every year. So, it is of great significance to increase the wear resistance of railway switch steel. In this study, particulate reinforced Fe-based composite coatings were produced on the high carbon manganese rail steel (U71Mn) by laser cladding. The coatings' properties, such as microstructure, microhardness, and wear resistance, were investigated. The wear scar appearance was also detected using a white light interferometer. The results reveal that the composite coatings with good formation and a typical in situ particulate reinforced microstructure can be obtained in proper processing ways. The microhardness of laser cladding coatings reaches HV 750 to HV 800, while the average microhardness of railway steel without laser treatment is HV 390. Furthermore, the properties of wear resistance of the laser cladding coatings have increased by nearly eight times when compared to the untreated railway steel specimen. The adhesion strength of the coatings to the substrate reaches 88% of the shearing strength of the railway steel.