Advances in plasma technique for Hadfield-coated layers to enhance mechanical durability of R260 rail steel

Abstract

Hadfield steel plays a critical role in high-stress railway track components. This study investigates the potential of plasma powder additive technology for rebuilding railway heavy-haul parts. A comparative analysis of different filler metals, including flux-cored wire and electrode filler metals, focuses on microstructure, mechanical properties, and heat transfer during layer formation. Plasma welding ensures structural stability, essential for dynamic strengthening and fracture toughness. Microstructural evolution is examined via optical and electron microscopy, supported by spherical indentation and Vickers hardness testing. Energy Dispersive Spectroscopy analysis identifies chemical heterogeneity and grain boundaries carbides sources. Numerical simulations provide insights into heat accumulation, optimizing technological parameters to mitigate carbide precipitation and enhance microstructural quality. Results indicate that plasma-welded samples achieve, on average, a 42 % higher indentation yield strength compared to manually welded samples. The strain-hardening exponent is also higher in plasma welding 0.4-0.6 compared to manual welding (0.2). These findings significantly advance railway welding techniques with capability to improve rail surface durability under demanding conditions.