Determination of the Mechanical Performance of an L-PBF 316L Deposit via Multiscale Instrumented Indentation Tests

The optimization and the engineering development of AM products both require ac-curate, non-destructive techniques to extract their mechanical performances. The In-strumented Indentation Test (IIT) has such a potential, although it currently lacks standard procedures that are suitable for analyzing materials which are affected by internal residual stress (RS). Additionally, nanoindentation testing suffers from the presence of indentation size effects (ISE), which hamper the possibility of correlating the measured mechanical performance at different indentation depths or peak loads. This paper presents a novel IIT methodology that is based on new indentation param-eters which are then used to assign the desired mechanical performances of an L-PBF 316L SS alloy obtained via multi-load nano- and macro-IITs. It has been proved that the new indentation parameters can be successfully correlated across different dimen-sional scales, i.e., from the nanoscale to the macroscale. The secant loading stiffness versus depth plot can be used to assess the susceptibility of RS to relax during indenta-tion, which is an important performance factor for the engineering design of AM components. The successful correlation that has been found between EBSD analysis (in terms of crystal anisotropy, grain size and GND density) and nanoindentation testing at three subregions of the core zone of the investigated deposit confirms the validity of the proposed methodology for the full determination of the 3Ps, that is, process, properties, and performance of advanced AM products.