The Effect of Deposited Dust on SCC and Crevice Corrosion of AISI 304L Stainless Steel in Saline Environment

Crevice corrosion has become an important issue of the safety of AISI 304L austenitic stainless steel canister when exposed to the chloride environments located in coastal areas. Moreover, dust deposited on the canister surface may enhance the corrosion effect of 304L stainless steel. In this work, white emery was adopted to simulate the dust accumulated on the as-machined specimen surface. To investigate the effect of deposited white emery, chloride concentration, and relative humidity on the crevice corrosion behavior, an experiment was conducted on 304L stainless steel specimens at 45 °C with 45%, 55%, and 70% relative humidity (RH) for 7000 h. The surface features and crack morphology of the tested 304L stainless steel specimens were examined by SEM equipped with energy-dispersive spectrometry (EDS) and electron back scatter diffraction (EBSD). From the experimental results, a threshold RH for the stress corrosion cracking (SCC) initiation of AISI 304L austenitic stainless steel with different concentrations of chloride was proposed.

Spark plasma sintering of cemented carbide WC-10% wt. AISI 304L cemented carbides using nanopowders

Tungsten carbide (WC) cemented carbides with alternative binders to cobalt have been researched due to the low availability, high cost and toxicity of this element. Promising results have been found for the use of austenitic stainless steel microparticles of AISI 304L as binders in cemented carbides, since they have good wettability with WC and produce materials with mechanical properties and corrosion resistance comparable to cemented from the WC-Co system. In this context, this work aims to produce cemented carbides using a combination of WC nanoparticles and 10% AISI 304L stainless steel. The production of these composites will be carried out via sintering by spark plasma sintering at different temperatures. Density, densification, microstructure, hardness and fracture toughness of the samples will be analysed. It is expected to show the benefits of using nanoparticles to produce carbide, in addition to the effects of temperature in the sintering process. Finally, a comparison will be made with data found in the literature on cemented carbides from the WC-Co system that will indicate the possibility of replacing AISI 304L as a binder of these materials.

Effect of Cathodic Polarisation Switch-Off on the Passivity and Stability to Crevice Corrosion of AISI 304L Stainless Steel

The effects of cathodic polarisation switch-off on the passivation of AISI 304L stainless steel in air and its crevice corrosion susceptibility in 3.5 wt.% NaCl aqueous electrolyte were investigated. Scanning Kelvin probe (SKP) data showed that the oxide film is significantly destabilised and the rate of steel passivation in air is slowed down. Thermal desorption analysis (TDA) highlighted that hydrogen absorption is proportional to the applied cathodic current density. A special crevice corrosion set-up was designed to realise simultaneous reproducible monitoring of potential and galvanic current to study the impact of prior cathodic polarisation on crevice corrosion onset.