Investigation on Microstructure, Nanohardness and Corrosion Response of Laser Cladded Colmonoy-6 Particles on 316L Steel Substrate

Abstract

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.

Correlation of microstructural with corrosion behaviour of Ti-6Al-4V specimens developed through selective laser melting technique

“…In general, wider the semicircular arc's radius, greater will be the resistance. 62 On analyzing the obtained Nyquist plots, it is seen that all the SLM printed samples have a larger arc radius than the as-cast samples. 63…”

“…In general, wider the semicircular arc's radius, greater will be the resistance. 62 On analyzing the obtained Nyquist plots, it is seen that all the SLM printed samples have a larger arc radius than the as-cast samples. 63 Among the as-cast samples, the arc radius of the 0 h sample is found to be higher and also a decreasing trend is observed in the arc radius of the higher duration (6 and 30 h) as-cast specimens.…”

Effect of Y2O3 Content on Microstructure and Corrosion Properties of Laser Cladding Ni-Based/WC Composite Coated on 316L Substrate

“…In the Nyquist curves, Z' and Z" are the real and imaginary components of impedance, respectively. For a coating fabricated by laser cladding, the greater the impedance radius at low frequency, the be er the corrosion resistance of the coating [40]. It can be seen that after Y2O3 is added, the capacitive reactance arc radius increases significantly.…”