Effects of HVOF spray parameters on porosity and hardness of 316L SS coated Mg AZ80 alloy

High velocity oxy-fuel (HVOF) coatings are becoming more popular in a variety of applications that demand a dense surface with strong wear and corrosion resistance. The HVOF thermal spray technique was used to deposit 316L stainless steel on the magnesium alloy (AZ80). Response surface methodology (RSM) was used to optimize the following HVOF spray parameters to achieve higher hardness and reduced porosity: flow rate of oxygen (O), flow rate of LPG (L), feed rate of powder (F), spray distance (S), and flow rate of carrier gas (C). ANNOVA was performed to develop empirical relations between process variables and measured results. A sensitivity analysis was also carried out to determine the most critical parameter. Correlation plots revealed an inverse relationship between porosity volume percentage and microhardness (R2 = 0.92). 257 lpm (O), 61 lpm (L), 38 gpm (F), 231 mm (S), and 16.50 lpm (C) were identified to be the parameters related to the minimal porosity volume percentage (0.21 ± 0.013 vol%) and the maximum microhardness (367 ± 4 HV0.3). [Display omitted] •Optimization of HVOF spray parameters was done using RSM.•Porosity and microhardness had significant inverse linear correlation.•Oxygen and LPG flow rates were identified as the most influential factors.•The microstructure of SS coatings deposited on Mg alloy was dense with minimal porosity.•SS coatings had a substantially higher hardness than bulk stainless steel.