• Residual stresses in DED-Arc steel tubular parts were investigated using sectioning method; • Specimens with square, circular and oval cross-section profiles were printed and tested; • Demec gauge, laser scanning and digital image correlation were used for strain measurements; • Bending and membrane residual stress distributions in longitudinal and transverse directions were obtained; • Influence of wall thickness, interpass temperature and cooling method was quantitatively examined. Wire-arc directed energy deposition (DED-Arc), is a metal 3D printing technology that enables the production of large, intricate steel components with significant potential in structural engineering. The cyclic thermal history inherent to the DED-Arc process induces residual stresses, which can influence the structural performance of fabricated components. This study experimentally investigates residual stress distributions in seven DED-Arc steel tubular specimens fabricated using ER90S-D2 welding wire. These include three square hollow section (SHS) tubes with nominal thicknesses of 3.5 mm, 4.5 mm, and 5.5 mm, two 3.5 mm-thick circular hollow section (CHS) tubes with interpass temperatures of 150 °C and 350 °C and two 8 mm-thick oval sections with active and passive cooling. The sectioning method was used to measure residual stresses in both longitudinal and transverse directions. Released strains were recorded using a Demec gauge and, as an alternative, using digital image correlation (DIC); the results showed generally good agreement, but the accuracy of the DIC results was compromised in the case of large out-of-plane deformations. For the SHS tubes, tensile stresses appeared in the corners and compressive stresses in the middle of the faces in the longitudinal direction, while the transverse direction showed peak tensile stresses at the top and bottom. Similar distributions were observed across the SHS thicknesses, except in the thinnest tube, where local buckling altered the pattern. The CHS tubes exhibited high through-thickness bending stresses linked to interpass temperature, while membrane stresses were negligible. In the oval tubes, active cooling led to slightly higher residual membrane stresses. The presented results and findings offer key insights into the residual stress distributions in DED-Arc tubular parts, serving as a sound basis for model validation and the evaluation of structural performance.
Spinasa et al. (Tue,) studied this question.