The Effect of Heat Treatment on the Microstructure and Mechanical Properties of 316L Stainless Steel Coatings Deposited by Flame Thermal Spray

In this research, the effects of heat treatment on the microstructure, the oxidation and mechanical properties of 316L stainless steel coatings sprayed by flame spraying process were studied. The microstructure characteristics of the deposits were studied using the combined techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore, the mechanical properties were tested using the adhesion strength and microhardness tests. Coatings have been heat-treated at a range of temperatures between 900 and 1150 °C. Results indicate that by heat-treating the coatings at a temperature of 900 °C, it is possible to achieve higher adhesion strength and hardness values. This was attributed to the improvements in the coating microstructure during the heat-treatment, which resulted in an improvement in coating's mechanical properties through the formation of intermediate phases, and the establishment of metallurgical bonding within the coating microstructure. However, the results also indicate that by increasing the temperature to a degree higher than 1150 °C, there was a reduction in the coating's mechanical properties. This could be attributed to the grain growth, and coarsened precipitation of the equilibrium phases from supersaturated solid solutions.

Keywords:

Flame Spraying , Heat treatment , Coating