Effect of cladding direction on the microstructure and mechanical properties of Hadfield gradient layers on R260 rails

Abstract

Rolling Contact Fatigue (RCF) is a critical issue that degrades rail surfaces, leading to structural damage and reducing service life. Effective repair techniques, such as plasma cladding with powder filler metal, can restore rail integrity and enhance performance. This study investigates the influence of cladding direction on the microstructure and mechanical properties of Hadfield gradient layers deposited on R260 rails. The research focuses on how deposition orientation affects hardness, phase transformations, and microstructural evolution, particularly the formation of martensitic layers and carbide precipitation within the heat-affected and repaired zones. Optical and electron microscopy are employed for microstructural analysis, while spherical indentation and Vickers hardness testing assess mechanical performance. The study reveals that cladding direction significantly influences carbide distribution, martensitic transformation, and hardness gradients, ultimately impacting fatigue resistance and durability. A deeper understanding of these variations provides valuable insights into optimizing cladding strategies for improved rail repair outcomes. The findings contribute to developing advanced repair methodologies, ensuring prolonged rail service life and enhanced resistance to fatigue-induced failures. Additionally, the study examines the effect of the number of welding layers and movement patterns of the welding torch in cladding to eliminate the need for post-weld heat treatment. This research serves as a foundation for refining welding parameters and deposition techniques to achieve superior mechanical performance in repaired railway components, ultimately leading to safer and more reliable railway infrastructure.