Wire + arc additive manufacturing (WAAM) is a modern manufacturing process that has opened new possibilities for rapid builds and reductions in material wastage. This paper explores residual stress in WAAM Ti-6Al-4V walls built using three different deposition strategies: single bead, parallel path, and oscillation path. The effect of interlayer hammer peening and interlayer temperature was investigated for the single bead walls. We also examined the residual stress in compact-tension (C(T)) coupons extracted from large builds (walls) with crack orientation either parallel with or perpendicular to the build direction. This type of sample is often used for the measurement of the fatigue crack growth rate. The contour method was used for experimental determinations of residual stress. In addtion, residual stress in the C(T) coupons was estimated by finite element (FE) analysis. A good agreement was achieved between the contour method and FE analysis. The oscillation-path wall had the lowest residual stress values. For the single bead walls built with various process conditions, residual stress was significantly reduced after removing the substrate. A interlayer temperature of 110 °C resulted in much higher residual stress values in the wall (both tensile and compressive) compared to the continuous build, with much higher interlayer temperature.

Development of residual stress of high magnitude, to the extent of material yield strength and in some cases higher than yield strength, is one of the major challenges faced by components produced using the wire arc additive manufacturing (WAAM). This study focuses on aluminum alloy 5183 with respect to the residual stress formation and distribution in WAAM builds. Residual stresses were determined using the contour method. The effects of processing conditions, such as substrate thickness, interlayer temperature, and deposit height on the magnitude and distribution of residual stresses were investigated. Substrate thickness was found to have a major influence on the residual stress distribution along deposit height. Tensile residual stress up to the value of the material yield strength was present. The majority part of the deposit showed tensile stress while substrate showed compensating compressive residual stress. Lower interlayer temperature samples exhibited residual stresses of higher degree of magnitude compared with sample produced using higher interlayer temperature. Deposit height, i.e., total number of layers affected stress distribution pattern similar to substrate thickness.