RESUMEN
The capacity to endure harsh wear in demanding conditions in stainless steel drops under extreme nature and applications. Protecting the surface by providing a coating layer supports the usage in harsh conditions. In this work, SS316L is coated with AlCoCrFeNi high-entropy alloy (HEA) by atmospheric plasma spray process and annealed at 600°C for 2 hours. The AlCoCrFeNi HEA exhibited spherical particles with bcc phase and 20 µm particle size. The coating morphology revealed a uniform coating with a homogeneous distribution of HEA particles over a thickness of 150 µm. The coating post-annealing offered improved microhardness by 12% than the coated sample before annealing. The wear test was executed by varying load, sliding distance, and sliding velocity at normal temperature, 400°C and 600°C and the corresponding worn surface was analysed. The coated samples after annealing showed 57.6%, 87.5%, and 65.4% improved wear resistance at normal temperature than the coated sample before annealing at minimum levels of load, sliding velocity and distance. The wear rate of coated and annealed samples revealed 5.2%, 4.5%, and 4.4% better wear resistance at 400°C than the coated samples before annealing. The worn surface morphology showcased wear mechanisms to be delamination, abrasive wear, and oxide layer formation under all conditions.
The present work reports a novel study of plasma spraying of SS316L substrate using AlCoCrFeNi High-Entropy Alloy that marks the first attempt in analysing its hot wear performance.
RESUMEN
A lightweight AlSiBeTiV high entropy alloy (HEA) powder is synthesized by the ball milling process and is reinforced on SS410 through friction stir processing (FSP). Subsequently, the annealing process is conducted on the processed samples at 450, 600, and 750°C for 120 mins. The grains are refined at 600°C by 23.3% than the processed HEA sample. A higher microhardness of 672 HV is attained on the processed HEA sample annealed at 600°C due to the synergistic effect of FSP and annealing through refined grains. The electrochemical corrosion under a 3.5 wt.% NaCl environment, and the hot corrosion under the salt mixture environments of 75% Na2SO4 +25% NaCl, and 60% Na2SO4 +20% NaCl + 20% V2O5 at 800°C for 50 h are investigated on the processed samples. The microstructure, induced corrosion products, and elemental distribution of the corroded surface of the annealed processed HEA sample are evaluated by morphological analysis. The induced oxidation effect enhances the Cr2O3 and TiO2 films on the corroded surfaces leading to higher corrosion resistance. A high corrosion resistance appears on the annealed processed HEA sample through the formation of a stable passive layer, hindering the pitting corrosion mechanism, grain refinement, and homogeneous distribution.
So far, the majority of work focuses on Al and composites. However, the current work made a surface modification on SS410 steel by reinforcing lightweight HEA particles through friction stir processing followed by the annealing process. The lightweight AlSiBeTiV HEA particles are reinforced in SS410 through FSP and subsequently annealing process is performed for enhancing the refined grain structure.Corrosion behaviours of processed samples at room and high temperature and the effect of annealing on corrosion behaviours of HEA reinforced steel are a novel area in materials science.
RESUMEN
316L steel is predominantly used in manufacturing the components of high-pressure boilers, heat exchangers, aerospace engines, oil and gas refineries, etc. Its notable percentage of chromium offers resistance against corrosion and is mostly implemented in harsh environments. However, long-term exposure to these components in such environments can reduce their corrosion resistance property. Particularly at high temperatures, the oxide film formed on this type of steel reacts with the chloride, sulfides, sulfates, fluorides and forms intermetallic compounds which affect its resistance, followed by failures and losses. This work is focused on investigating the hardness, microstructure and corrosion resistance of the laser cladded Colmonoy-6 particles on the 316L steel substrate. The cladded specimens were dissected into cubic shapes and the microstructure present in the cladded region was effectively analyzed using the FESEM along with the corresponding EDS mapping. For evaluating the hardness of the cladded samples, the nanoindentation technique was performed using the TI980 TriboIndenter and the values were measured. The potentiodynamic polarization curves were plotted for both the substrate and clad samples at 0, 18, 42 and 70 h for revealing the corrosion resistance behavior. In addition, the EIS analysis was carried out to further confirm the resistance offered by the samples. The surface roughness morphology was evaluated after the corrosion process using the laser microscope, and the roughness values were measured and compared with the substrate samples. The result showed that the cladded samples experience greater hardness, lower values of surface roughness and provide better corrosion resistance when compared with substrate samples. This is due to the deposition of precipitates of chromium-rich carbide and borides that enhances the above properties and forms a stable passive film that resists corrosion during the corrosion process.
