Residual stress evaluation in lPBF-Printed biocompatible stainless steel 316 l lattice structures: experimental and simulation based approach

This study examines thermo-mechanical behaviour of six lattice designs made of SS316L in strut (Octet Truss, Honeycomb, Dodecahedron) and sheet-based Triply Periodic Minimal Surface (TPMS) (Gyroid, Split-P, Diamond). It applies simulations as well as experimental approaches. Leftover stresses were assessed by using X-ray diffraction and Williamson-Hall analysis. Z-displacement measurement was done with a 3D scanner with a measurement uncertainty of ±0.05 mm, and then compared to thermo-mechanical simulations result obtained using Simufact Additive. Changes in stress were also largely affected by the geometry. TPMS lattices had increased and localised residual stresses up to 526 MPa and exhibited an increased vertical displacement (± 0.026 mm) because of the heat flow restrictions and geometry limitations. The predictions of simulations were in close agreement with the experimental results with a variation of less than 6%. Microhardness showed a height gradient that was dependent on height and reduced by up to 45HV in regions with high residual stress. These findings provide a basis of relating lattice design, residual stress, distortion, and mechanical behaviour, which are of great value in designing with geometry consideration and enhancing processes in the metal additive manufacturing.