ANALYZING TENSILE STRENGTH, HARDNESS, AND MICROSTRUCTURE OF INCONEL 625 AFTER QUENCHING THROUGH WATER, 3.5% NaCl, and 3.5% HCl

Abstract

Inconel 625 is a high temperature bearing and corrosion resistant alloy. Its high strength, good hardness and remarkable ductility make this alloy widely used in aerospace, turbines, automotive, engine valves, fuel injectors, fasteners, etc. It is considered as heat treatable alloy. The present work deals with heating the Inconel 625 alloy to elevated temperature and cooling through quenching media, including water and chloride solutions. The tensile and hardness properties of the quenched samples were analyzed in the light of the ‘untreated' sample available in ‘cold-rolled’ condition. The microstructural analysis was done using optical microscopy and FESEM. Apart from γ matrix and twin boundaries, Ti/Nb rich carbonitrides and needle-δ phases were reported in the treated samples. A slight corrosive degradation was also observed in the chloride-solution quenched samples. The XRD analysis proves the occurrence of oxide formation in Cr present at the γ grain boundary. As a result of quenching, the tensile and yield strength were reduced with a gain of overall elongation. Hence, quenching methods are beneficial for improving the ductile nature of Inconel 625 alloy, and hence, the hardness of the quenched products was found to be less than the ‘as received’ sample.