Microstructural, thermo-optical, mechanical and tribological behaviours of vacuum heat treated ultra thin SS304 foils

The purpose of this present study was to evaluate the effect of vacuum (i.e., 10⁻⁵ mbar) heat treatment at 300 to 1100 °C on morphological, thermo-optical, mechanical and tribological properties of 75 μ m thin SS304 foils. Microstructural, morphological and surface properties of the foils were characterized by field emission scanning electron microscopy (FESEM), profilometry, x-ray photoelectron spectroscopy (XPS) and water contact angle (WCA) measurement techniques, respectively. The x-ray diffraction (XRD) was employed to identify the phase of SS304 foils after different heat treatment temperatures. Thermo-optical properties such as solar absorptance ( α _s), reflectance ( ρ _s) and IR emittance ( ε _ir) were also evaluated. The nanomechanical properties i.e., nanohardness (H) and Young's modulus (E) of as-received and heat treated SS304 foils were evaluated by the nanoindentation technique. Tribological and tensile properties i.e., yield strength ( σ _y) and percentage of elongation of different heat treated foils were also investigated by single pass scratch tests and universal testing machine, respectively. Noteworthy grain growth of SS304 was observed beyond vacuum heat treatment temperature of 700 °C. As a consequence, the magnitudes of both H and E data of SS304 were significantly decreased beyond the vacuum heat treatment temperature of 700 °C. Further, the hardness data followed the well known Hall–Petch relationship. On the other hand, the tribological property of SS304 was significantly deteriorated beyond the vacuum heat treatment temperature of 700 °C. The tensile strength of the foils was also altered after the heat treatment. (paper)