SS 316L by thermal treatments

Type 316L is molybdenum-bearing austenitic stainless steel which is more resistant to general corrosion and pitting/crevice corrosion than the conventional chromium-nickel austenitic stainless steels such as Type 304. The alloy also offers higher creep, stress-to-rupture and tensile strength at elevated temperatures and thus is considered to be good candidates for bipolar plate materials for the polymer electrolyte membrane fuel cell (PEMFC). While operating at high temperatures (>100°C), the stainless steel can be easily passivated. The major concern for SS316L then would be the possibility of additional film growth and its possible effect on the interfacial contact resistance and the corrosion resistance. In this study, the contact resistance has been evaluated for SS316L samples pretreated at high temperatures for different periods of time. The surface morphology and the composition change of these samples were analyzed by high-resolution SEM/EDS. Also, the polarization curves of these heated samples in 0.5M sulfuric acid solution at 25°C were measured by linear scanning voltammetry. The results showed that a stable passive film formed due to the thermal treatments. The interfacial contact resistance increased with heating time but not necessary with elevated temperatures.