Investigation of the microstructure, tribological behavior and residual stress of Tribaloy T400 coating on gas turbine blades processed by laser cladding

Abstract This study investigates the effect of substrate preheating on the residual stress, microstructure, and wear behavior of Tribaloy T400 coatings laser-cladded onto GTD-111 nickel-based superalloy substrates. Coatings were fabricated using a continuous-wave Nd:YAG laser at six preheating conditions ranging from room temperature to 700 °C. The microstructure, phase composition, residual stress, and tribological performance were characterized using SEM/EDS, EBSD, XRD, and pin-on-disk testing. Results indicate that preheating significantly influences coating quality. At 600 °C, a notable reduction in residual tensile stress was observed (∼1600 MPa versus ∼2900 MPa in non-preheated samples), attributed to increased FCC phase content and refined equiaxed grains. The volume fraction of the brittle Laves phase decreased from ∼70% to ∼30%, improving ductility and stress distribution. Wear performance also improved: the coefficient of friction dropped from 0.52 to 0.40, and the specific wear rate decreased by ∼20%. Moreover, preheating enhanced coating–substrate metallurgical bonding by increasing dilution to ∼14.1%, without promoting excessive elemental interdiffusion. In contrast, the non-preheated sample exhibited poor adhesion, severe cracking, and minimal dilution. Overall, substrate preheating was shown to be an effective strategy for tailoring the microstructure and enhancing the mechanical integrity and wear resistance of T400 coatings. Preheating at 600 °C offered the best balance between stress relief, microstructural refinement, and tribological performance, making it a promising condition for industrial applications in gas turbines and high-temperature wear environments.