Investigation of microstructure and corrosion behavior OF IN718 superalloy fabricated by selective laser melting

Abstract In the present study, the microstructure and corrosion behaviour of additively manufactured IN718 superalloy samples investigated. The specimens were fabricated using a selective laser melting method with different scanning strategies (island/continuous) and speed. The samples were then heat-treated with a standard procedure of homogenizing at 1080°C (1.5 hrs.), solution at 980 °C (1.0 hr.), and two-step aging at 720/620 °C. The microstructure, analysis, hardness, and electrochemical behaviour of samples were investigated. The microstructural observations and phase analysis showed several phases in as fabricated and heat treatment conditions, which alter with the fabrication process. The γ’/γ’’ and δ phase contents of heat-treated samples increase by the factor of about 3.0, and the hardness values rise by 45-51%. The electrochemical results demonstrate that the IN718 fabricated by island strategy and higher speed scan (700 mm/s) possess better corrosion resistance and the highest breakdown potential.