Critical Assessment into Bending Strength and Ductility of Inconel-625 Alloy Exposed to Water, HCl, and NaCl Media

Inconel-625 is known for its exceptional corrosion resistance. It is highly strong metal due to the presence of solid solution. It is also recommended for high-temperature applications. Usually, the solution heat treatment is done on Inconel-625 alloy at a temperature range of 700–1200 °C for the period of 2–5 h. In this work, an attempt has been made to heat treat the thin plates (of 2.5 mm thickness) Inconel-625 alloy at a temperature level of 900 °C for a short holding time of 15 min and then, followed by quenching in three different media like normal water, 3.5% HCl solution, and 3.5% NaCl solution. By this way, the effect of quenching in corrosive media on the bending stress and toughness of the samples was investigated. The microstructure of the samples was containing mainly γ-matrix with multiple twins on the grains. δ-strings were also present in each sample. Also, the fine metal carbides could be recognized. In all the quenched samples, no effect of corrosive media was reported at the microscopic level which was further confirmed by the XRD results. No considerable loss of bending stress and toughness was recorded in the HCl solutioned sample. However, a significant improvement in the ductility was observed in the water quenched samples with and without carrying NaCl content.