Prediction of Residual Stresses in L-PBF Ti-6Al-4V Fatigue Specimens Using a Thermo-Mechanical Finite Element Model

Laser Powder Bed Fusion (L-PBF) is an additive manufacturing process that is becoming widely adopted in the automotive, aerospace, and biomedical industries. It uses a laser to melt metal in the form of powder to build parts in a layer-by-layer fashion based on an imported CAD geometry. The constant remelting of previous layers can produce unwanted thermally induced residual stresses in the part due to large thermal gradients, which can drastically reduce the fatigue life of the material. Predicting these residual stresses within the as-built part would be advantageous because one could better understand how the part will perform in an industrial setting. This study aims to use a combined thermo-mechanical finite element model to simulate the printing of fatigue specimens using L-PBF. The specimens are built based on Ti6Al4V material properties using a set of nominal process parameters. After the mechanical model of the specimen containing the induced residual stresses is created, the fatigue life of the part will be analyzed using constant amplitude stress-controlled loadings in FE-safe, and the results will be compared with that of a wrought Ti-6Al4V specimen.https://scholarsjunction.msstate.edu/fea/1005/thumbnail.jp