Effects of Print Parameters and Heat Treatment on Fatigue of Laser Powder Bed Fused Inconel 718
Abstract
Laser Powder Bed Fusion (L-PBF) allows for complex geometry parts to be fabricated without sacrificing mechanical properties/behaviors. Though this process is greatly beneficial, it is still hindered by its build volume capabilities as well as the present of detrimental particles and defects in its microstructure after the printing process. This research applies to the printing parameters and post processing of LPBF’ed Inconel 718 (IN718) and their effect on fatigue performance of the material. Samples were printed with laser speed varying from 1000-1500 mm/s while varying energy density per volume from 45.5-68.2 J/mm³. Samples were grouped and subject to different heat treatment (HT) combinations including homogenization (HG), hot isostatic pressing (HIP), and solution aging (SA). The porosity and microstructures of the samples were analyzed through optical and scanning electron microscopes (OM and SEM, respectively) to determine optimal print parameter and heat treatment strategy. The lowest amount of porosity with the smallest average pore diameter (15.58μm) was observed in samples printed with 54.5 J/mm³ energy density. Laves phase particles were present in both as-printed and HG samples. Al2O3 defects were present in all samples but were controlled in samples subjected to the SA treatment. HIP+SA samples exhibited optimal microstructure and grain boundary development. Fatigue results showed the HIP+SA was able to increase fatigue life >100% when compared to the as-printed state.
Citation
Marino, Anthony Philip (2022). Effects of Print Parameters and Heat Treatment on Fatigue of Laser Powder Bed Fused Inconel 718. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /198786.