The simulation results are in good agreement with the experimental measurement within a range of 0.2–9% error. FEM simulation results on residual stress and distortions are validated by experimental measurements on Inconel 625 and presented in the article. The modeling approach incorporates the features of plasticity and hardening mechanism into the FEM environment. This study introduces an analytical approach and a multi-physics based finite element modeling (FEM) approach for rapid estimation of the residual stresses and distortions of the parts encountered in the DMLS process. Although researchers have been studying for more than a decade to understand and model the complex physical phenomena involved in the DMLS process, the solutions provided in the literature are not fully applicable to the industrial problems due to long computational time. Therefore, the development of a fast and reliable simulation tool is essential to predict residual stresses and resulting distortions so that preventive actions including effective support design or building in a different direction can be taken. The evolution of temperature during AM processes such as direct metal laser sintering (DMLS) has a considerable effect on residual stresses and thus undesired distortions in the parts. Shorter vector lengths with interlayer scan rotations are optimal for micro-crack mitigation.Īdditive manufacturing (AM) is growing rapidly in the advanced industrial applications to reduce the cost and time of the manufacturing and assembly processes. Furthermore, alternating long vector lengths create 100%–230% more micro-cracks than alternating short vector lengths, which are more beneficial than the 67° continuous rotation strategy due to reduced in-process stresses. Scan rotations reduce micro-cracking propensities by 12%–62% compared to zero scan rotations due to more homogeneous stress distribution during build progression. Parts are processed with alternating and continuous inter-layer scan rotation strategies. ![]() ![]() Thicker parts and long vector length are more susceptible to micro-cracking due to earlier transition to positive stress triaxiality states demonstrated through finite element modeling. All micro-cracks exhibit inter-dendritic morphologies in the vicinity of the cracked boundaries, suggesting a solidification cracking mechanism. ![]() Microstructure characterization shows micro-cracks aligned with the build direction and melt-pool boundaries. Thirty-two parts, including ten different scan strategies and four different wall thicknesses between 0.25 mm and 1.00 mm, are studied and compared with the conventional continuous 67° scan rotation strategy. Thin-wall components made of a hard-to-weld Ni-based superalloy, RENÉ 108, are fabricated using laser powder bed fusion.
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