Abstract
Residual stress evaluation in directed energy deposition processes is of great importance, since its underestimation or lack of control can result in mechanical properties degradation of the produced components and even failure in service, particularly when there is an overlap of tensile stresses originating from repeated thermal cycles. The objective of this study was to perform a systematic analysis of the residual stress generation in wire-arc directed energy deposition produced steel samples. For this purpose, a finite element model was first developed and validated in order to understand the stress distribution in the longitudinal and transverse sections. In addition, test specimens with different numbers of deposited layers were produced by a bidirectional continuous strategy using the cold metal transfer deposition modality, and subjected to experimental residual stress measurements employing an optical hole-drilling method. Dimensional, microstructural, and hardness profile analyses were performed as well. The results obtained in this study demonstrate that the residual stress distribution is not uniform in the wire-arc directed energy deposition produced samples because of the different cooling rates and deposited material volume in the different parts of the studied components. Moreover, different numbers of beam layers, and consequently varying thermal cycles have a significant influence on the type, magnitude, and distribution of the residual stresses, as well as on the dimensional stability and microstructure changes.