Effect of Heat Treatment on the Ductility of Inconel 718 Processed by Laser Powder Bed Fusion

Abstract

Inconel 718 is a precipitation-hardening alloy, with a typical heat treatment consisting of solution annealing before a two-stage ageing process. Depending on the heat treatment procedure, strength or ductility can be enhanced, typically at the cost of the other. This study aims to determine a heat treatment procedure suitable for applications that require high ductility. Tensile tests of Inconel 718 processed by laser powder bed fusion additive manufacturing has been carried out on specimens subjected to different heat treatment procedures. The results show that solution annealing above 1010 °C followed by a two-stage ageing at 720 °C/8 h with furnace cooling to 620 °C/2 h and final holding at 620 °C/10 h, produce elongation at break of above 30% tested at room temperature and above 24% tested at 650 °C.