The creep behavior of IN718 alloy fabricated by selective laser melting compared to forging

In this study, the effect of microstructure on the creep property of SLM-built IN718 after heat treatment (hot isostatic pressing, solution and aging treatment) was investigated based on a comparative analysis of forged N718, focusing on the influence of grain morphology. The average creep life, area reduction uniform elongation of SLM-built IN718 alloy are only 42 %, 50 % and 26 % of forged IN718 alloy, respectively. In the steady-state creep stage, few slip system within individual grains of SLM-built IN718 alloy with the irregular grain morphology is activated, while most of the slip systems of forged IN718 alloy with the regular grain morphology can be activated. The irregular grain morphology and a wide distribution of grain size in SLM-built IN718 alloy leads to the more serious stress concentration at the grain boundary, the micro-cracks preferentially initiate along fine-grain boundary and triple point at grain boundary in SLM-built IN718 alloy.