Microhardness as a Function of Process Parameters in Additively Manufactured Alloy 718

Abstract

Mechanical properties can be linked to various material features including defects and microstructure, which are demonstratively different between additively manufactured (AM) and traditionally manufactured alloys. Vicker’s hardness (HV) testing can be correlated with various mechanical properties such as strength and wear resistance. In this work, the relationship between HV and laser powder bed fusion AM process parameters was explored for nickel-based superalloy 718 using machine learning regression methods. Additionally, HV measurements were taken spatially across the samples and examined for the extent and location of variation in each sample. Materials characterization was used to observe microstructure differences for discussion of HV variation with respect to material morphology and niobium microsegregation which is then related to thermal changes because of processing parameter modifications. The results from this work can be used to continue to understand the processing–structure–properties relationship and to explain within sample variation for improved mechanical properties in AM.