Influence of scanning strategy on residual stresses in laser powder bed fusion manufactured alloy 718: Modeling and experiments

• Residual stresses are a known phenomenon in additively manufactured materials. The residual stresses increase the risk of cracks, limit in-service performance, and distort printed parts. In this work, thermo-mechanical finite element models using the hatch-by-hatch and layer-by-layer approach, and the inherent strain method has been developed and applied to predict the effects of different scanning strategies on the deflection and the residual stresses of two PBF-LB processed geometries. To account for viscoplasticty and relaxation effects, a mechanism-based material model have been implemented and used. It is shown that the hatch-by-hatch approach and inherent strain method both successfully predicted the experimentally measured deflections of the first geometry, which was printed using different scanning directions. To predict the stress field experimentally, high-energy synchrotron measurements have been used to. The thermo-mechanical models and the inherent strain method both captures the trend of experimentally measured residual stress fields, although with an overall underprediction. The predictions of the models were evaluated, and their accuracy discussed in terms of physical aspects of the Powder Bed Fusion – Laser Beam process.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Material model

high energy synchrotron diffraction

EBSD

deformations

residual stresses

process parameters

finite element method

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)