Material characteristics of laser-cladded hypereutectoid rail steels

Abstract

The impact of preheating conditions and carbon dilution on the microstructural and mechanical properties of laser cladded rails at various number of deposition layers has been investigated for hypereutectoid steel grades typically used under heavy hall conditions. The microstructures in the HAZ showed that formation of martensite, which has a detrimental effect on behaviour in wheel-rail contact, was successfully inhibited by increasing the length of the preheated region using a preheating temperature of 350C. Dilution of carbon from the hypereutectoid substrate was observed and its effect on the microstructures on the 410L ferritic stainless-steel deposits was investigated. The formation of the ferrite in the 410L cladding layers was attributed to the very low carbon content, and no carbide formation was observed on boundaries of the ferritic grains. The thickness of the dilution band was determined to be approximately equal to the thickness of the first cladding layer. Mechanical charaterization of the 410L deposits undertaken in terms of Vickers microhardness was correlated with the observed microstructural morphologies. © 2021 Informit