Influence of sintering temperature on the corrosion and wear behaviour of spark plasma–sintered Inconel 738LC alloy

Inconel 738 low carbon is a nickel-based superalloy that is widely used in the marine and petroleum industries, where it is subjected to an aggressive erosive and/or corrosive environment. Degradation due to erosion and corrosion often has a negative impact on the material’s long-term performance. This study aims to improve the mechanical properties and wear resistance of the material. This was achieved by using spark plasma sintering (SPS) technique to fabricate IN738LC superalloy. The elemental powders were prealloy in a tubular mixer for a period of 12 h. The samples were sintered at four different temperatures of 900, 1000, 1100 and 1200 °C under a pressure of 50 MPa, heating rate of 100 °C/min and holding time of 5 min. Wear test was conducted on the sintered alloys at 15, 25 and 35 N loads. Potentiodynamic polarization tests were performed in 3.65% NaCl and 0.5 M H2SO4 solutions. Worn surfaces and microstructural analyses of the sintered alloys were conducted using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and polarized optical microscopy (POM). Microstructural evaluation of the alloys revealed that there was a homogenous dispersion of elemental composition, with less morphological defects. Wear results showed that the sample sintered at 1200 °C has the highest resistance to wear and corrosion attack. It also possesses superior hardness property. Therefore, the new material is suitable for application in a highly corrosive environment and also for high strength applications.