In this study, the effects of heat treatment on the microstructure and mechanical properties of cold sprayed stainless steel 316L coatings using N₂ and He as propellant gases were investigated. Powder and coating characterizations, including coating microhardness, coating porosity, and XRD phase analysis were performed. It was found that heat treatment reduced porosity, improved inter-particle bonding, and increased ductility. XRD results confirmed that no phase transformation occurred during deposition. Significant increase in UTS and ductility was observed for the annealed specimens obtained with nitrogen propellant, whereas little changes were observed for the helium propellant produced specimen.

The influence of laser modes and power on the tribological behavior of additively manufactured Inconel 718 alloys using the direct energy deposition (DED) technique was investigated. The samples were fabricated with continuous wave (CW) and pulse wave (PW) laser modes using 700, 900, and 1100 W laser power. The samples exhibited high hardness (3-5 GPa) and modulus (150 – 200 GPa) which increases with the laser power for CW and PW fabricated samples, and this was associated with the increasing densification and hardening secondary phase. The coefficient of friction increases with laser power for the CW samples but decreases for the PW samples. The samples showed an improved wear rate ranging between 25 and 70 × 10⁻⁵ mm³/Nm. Pulse wave samples demonstrated better tribological behavior compared to continuous wave at any laser power. The dominant wear mechanism is the three-body abrasive wear followed by localized and discrete adhesion wear mechanism.