# Microstructure and Dynamic Properties of CrMnFeCoNi(Al)8 Laser Cladding Coatings on Urban Rail Wheels

## TL;DR

This study explores laser cladding coatings on urban rail wheels to improve their durability and performance under challenging conditions.

## Contribution

The study introduces a high-entropy alloy coating with optimized Al content for enhanced mechanical and corrosion resistance in rail wheels.

## Key findings

- Increasing Al content leads to a dual-phase microstructure with grain refinement and improved mechanical properties.
- The CrMnFeCoNi(Al)8 coating achieves a microhardness of 450 ± 5 HV0.5 after heat treatment, a 12.6% increase.
- The coating shows better corrosion resistance with a 0.07 V higher open-circuit potential than the CL60 substrate.

## Abstract

Urban rail wheels endure prolonged exposure to frequent starts and stops, heavy cyclic loads, and complex track conditions, which often lead to premature failure modes such as wear, fatigue cracking, and corrosion in conventional wheel materials. These limitations restrict their ability to meet the evolving demands of modern rail systems for enhanced durability and performance. To address this, the present study uses laser cladding to deposit high-entropy alloy coatings with systematically varied aluminium content onto wheel substrates. The study compares phase composition, microstructure, and mechanical properties across the different coatings. Results show that increasing Al content transforms the coating microstructure from a single face-centred cubic (FCC) phase to a dual-phase structure of FCC and body-centred cubic (BCC) phases, accompanied by notable grain refinement. Among the variants, the CrMnFeCoNi(Al)8 coating has the densest microstructure and the most favourable mechanical performance. It achieves a microhardness of 399.62 HV0.5 in the as-clad state and 450 ± 5 HV0.5 after heat treatment, representing an increase of approximately 12.6%. This coating also demonstrates improved corrosion resistance, with an open-circuit potential 0.07 V higher than the CL60 substrate. Multi-body dynamics simulations confirm that the clad wheels maintain excellent operational stability and safety under service conditions.