Mechanical and Microstructural Characteristics of Inconel 625 Alloy After Exposure to Elevated Temperature and H₂SO₄ Solution Quenching

Inconel 625 alloy retains high strength and corrosion resistivity even in high temperature. Therefore, it is widely used in area of automobiles, aircraft, oil, and chemical industries. The present work attempts to check the mechanical properties, such as, tensile, bending, and compressive strength of Inconel 625 alloy after undergone through high temperature of 750 °C followed by quenching in 12.5%, 18.5% and 24.5% H₂SO₄ solution. The properties of thermally treated and quenched samples were compared with those of untreated sample. The optical microscopy and XRD analysis were also done to check any possible corrosive degradation after chemical quenching. Despite no visible changes in the microscopic images, the XRD analysis reveals that heat and acidic treatments induce the formation of secondary phases (Cr₂O₃ and CrVO₄) in Inconel-625 apart from primary γ peaks. In the thermally treated samples, the “yield strength (YS)” and “ultimate tensile strength (UTS)” decreased to an extent of 12% and 2.3%, respectively, but the elongation, a measure of ductility, increased by 9.5% in all the three treated samples. The H₂SO₄ solution quenching at a higher concentration of 24.5% reduced compressive and flexural strengths by up to 10% and 17%, respectively.