Effect of off-axis laser incidence on residual stress in laser-based directed energy deposition of 316L stainless steel
Source abstract
Abstract
Residual stress limits dimensional accuracy and service performance in the Laser-based Directed Energy Deposition (DED-LB) of 316L stainless steel. Process-integrated mitigation was demonstrated using off-axis (oblique-incidence) laser delivery. A 20 mm-thick multilayer build was characterized by neutron diffraction, neutron tomography, electron backscatter diffraction (EBSD), and Vickers macrohardness mapping. Residual stresses were confined to ±100 MPa, with interior tension and surface-adjacent compression; neutron tomography measured ∼0.001% porosity for pores ≥50 μm. Hardness of 150–230 HV20 colocated with compressive zones, and EBSD showed elongated columnar grains with position-dependent texture. The reduced stress state is attributed to the enlarged projected footprint and lower peak irradiance of off-axis delivery, which spread heat laterally, reduce the thermal gradient (G) and cooling rate (T˙), and favor conduction-mode melting. These results establish off-axis DED-LB as a route to in situ residual-stress control and microstructural tailoring while maintaining negligible resolved porosity in additively manufactured 316L components. The bulk, through-thickness maps and datasets provide component-scale validation to calibrate models and support process qualification.
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Research context
OpenAlex topics: Additive Manufacturing Materials and Processes · High Entropy Alloys Studies · Welding Techniques and Residual Stresses
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Future Industries Institute, Adelaide University 1 , Mawson Lakes, South Australia 5095,
LaserBond Ltd. 2 , Cavan, South Australia 5094,
Australian Nuclear Science and Technology Organisation 3 , Lucas Heights, New South Wales 2234,
Swinburne University of Technology 4 Department of Mechanical and Production Design Engineering, , Hawthorn, Victoria 3122,
Funding
Australian Research Council
References (42)
Show source-provided references
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42. See the supplementary material online for Figures S1–S10. Figure S1 validates the neutron-diffraction residual-stress reconstruction via traction-free surface checks, summary statistics, and a comparison between plane-stress and constant-d0 solutions. Figures S2–S10 provide EBSD band-contrast, inverse pole figure, and grain-boundary overlays together with phase maps for sections normal to the build-up, scanning, and overlap directions at left, center, and right positions. These data document columnar/epitaxial growth, location-dependent texture, and grain-boundary character that support the microstructure-hardness-stress interpretations in the manuscript.