Effect of Heat Treatment on Corrosion Behavior of 316L SS Coated AZ80 Magnesium Alloy Through HVOF Technique

316L stainless steel (SS316L) coatings were deposited on a AZ80 magnesium alloy by HVOF thermal spraying to enhance its corrosion behavior. Coatings with low porosity (0.21 ± 0.013%) and high microhardness (367 ± 4 HV0.3) were obtained from the optimized operating parameters, including an oxygen flow rate of 257 lpm, spraying distance of 231 mm, LPG flow rate of 61 lpm, carrier gas flow rate of 16.50 lpm, and powder feed rate of 38 gpm. The heat treatment (350–550 °C, 5–10 h) study revealed that SS316L surface roughness (using a 3D optical profilometer) remained unaffected; while, AZ80 Mg alloy roughness increased strongly (179–1140%). Electrochemical studies revealed that the SS316L-coated samples exhibited consistent corrosion potential (− 0.28 to − 0.23 V) and minimal corrosion current (4.16 ± 0.0055–4.60 ± 0.012 μA/cm2) versus fluctuating potential (− 1.74 ± 0.0183 V to −1.38 ± 0.035 V) and higher corrosion currents (186 ± 6.63–620 ± 10.12 μA/cm2) of bare AZ80 magnesium alloy. The fluctuating behavior in the bare AZ80 Mg alloy was related to variations in the Mg17Al12 precipitates at higher heat treatment temperatures. Also, SEM and EDX analyses of post corrosion products confirmed the protective role of SS316L coatings.