Effects of different HVOF thermal sprayed cermet coatings on tensile and fatigue properties of AISI 1045 steel

The objective of the present work was to investigate the effect of different cermet coatings on tensile and high-cycle fatigue properties of AISI 1045 steel using High-Velocity Oxygen Fuel (HVOF) thermal spray process. In this study, the WC-12Co, WC-10Co-4Cr, and Cr3C2-25NiCr cermet powders were coated onto the surface of annealed AISI 1045 steel specimens via the HVOF thermal spray process. The corresponding HVOF thermal spraying results were compared with those obtained from hard chrome (Cr) electroplating process. The thermal spray coated specimens showed load drop tendency beyond the yield point with significant work hardening in the tensile results, but low fatigue life than the base material in high-cycle fatigue results due to defects and poor adhesion at the interface. However, those cermet coating materials showed higher fatigue strengths than the hard chrome plated material. Fractography tests showed that fatigue strength was not only dependent on residual stress, but also influenced by the modes of fatigue failure related to the coated layer's cohesion and adhesion strength. Overall, the Cr3C2-25NiCr cermet coating is preferable due to its less porosity, high fatigue property, and better adhesion than the other coated materials.