Integrated AHP and metallurgical approach: comparing welding techniques and characterizing NiCrBSi coatings in hardfacing

In this study, the analytic hierarchy process (AHP) was employed to select the optimal hardfacing method from shielded metal arc welding (SMAW), metal inert gas (MIG) welding, Tungsten inert gas (TIG) welding, automatic TIG welding, and plasma transferred arc welding (PTAW). PTAW was identified as the superior technique, demonstrating higher microhardness (501.8 HV1) and a composite grade of 0.47 compared to other methods. The research used a 130 mm × 100 mm × 30 mm SS410 steel substrate and Colmonoy-4 nickel-based alloy powder with a grain size of 40–60 µm. The key process parameters transferred arc current (TC), powder feed rate (PF), speed of oscillation (SO), welding speed (WS), and plasma gas flow rate (PG) were identified through literature and preliminary studies. Microstructural analysis revealed the presence of carbides and borides of nickel, chromium, and iron, including α-Cr7C3, β-(Cr, Fe)7C3, δ-Cr23C7, θ-Ni3B, ψ-CrB, μ-Cr2B, and γ-Ni, which contributed to the enhanced hardness. The findings suggest that industries can enhance component life and reduce costs related to raw materials, rework, and surface defects by adopting optimized PTAW parameters.