Additive manufacturing (AM) has attracted a lot of attention from science and industry in the past few years due to its advantages, such as the possibility of manufacturing complex geometries and material efficiency. Among AM processes, Wire Arc Additive Manufacturing (WAAM) is widely used form the production of large parts, which is executed by depositing layers of metal on top of each other, until a desired 3d shape is created. Despite its benefits, if it is poorly conducted, AM parts can suffer from microstructural and mechanical properties anisotropy and heterogeneity, and residual stresses. Residual stresses could negatively affect the fatigue life of the components and increase susceptibility to stress corrosion cracking and hydrogen embrittlement. They could be high enough to cause detachment of the deposited material from the substrate during manufacturing or cause undesired distortions, which negatively affect the geometrical precision of the parts. Understanding the formation mechanism and evolution of the residual stresses during the AM process is the key to a successful design and component performance. Experimental methods for analyzing residual stresses, despite providing valuable insight into the magnitude and distribution of residual stresses, are usually restricted to a few points and cannot capture the whole distribution of the residual stresses in the component. Besides, their in-situ implementation imposes more complexity and experimental difficulties. Numerical methods, on the other hand, give a comprehensive view of the residual stress and distortion of the whole part. Although, their reliability depends on the accurate verification and validation of the model [1–3]. Therefore, a combination of both methods could readily give a comprehensive insight into the formation mechanism and evolution of the thermal and residual stresses in AM parts. This work, therefore, aims to investigate the residual stress formation and evolutions in S316L austenitic stainless steel parts manufactured by WAAM. XRD methods were utilized for measurement of the residual stresses and FE-based Abaqus software was used to numerically calculate the thermal and residual stresses in the parts via a thermos-mechanical model. The results show that the residual stresses in the longitudinal and build directions are the highest residual stresses of the component. While the distribution and magnitude of all stress components substantially change by depositing the subsequent layers.

References

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