Effect of path strategy on residual stress and distortion in laser and cold metal transfer hybrid additive manufacturing

Laser and cold metal transfer (laser-CMT) hybrid additive manufacturing is a novel process that allows the manufacturing of parts with high deposition rates. Residual stress and distortion caused by high heat input hinder the widespread use of this technology in producing large-scale components. This paper studies the effect of the path strategy on residual stress and distortion in laser-CMT hybrid additive manufacturing. Three path strategies viz. same direction motion (SDM), reciprocating motion (RM), and segmental reciprocating motion (SRM) are chosen. A finite element model is built to predict the residual stress and distortion of the thin-walled part with arc and line features. The adequacy of the model is proven by validation experiments. The thermal cycles are obtained by infrared thermography, the residual stress on the beads is measured by X-ray diffraction, and the distortions of the substrate are scanned by the structure light vision sensor. The temperature gradient, residual stress, and distortion of the samples deposited in different path strategies are analyzed using the validated model. The distortion of the substrate in depositing process by the SRM path strategy is smaller than that of the other path strategies. Finally, a manufacturing case for a commercial aircraft load-carrying frame demonstrates that industries can adopt Finite element (FE) analysis as a tool to optimize the path strategy for laser-CMT hybrid additive manufacturing.