Numerical simulation of plasma arc additive manufacturing process of titanium alloy blade under different deposition paths

Abstract

Due to the concentration of heat input in the plasma arc direct deposition technology, the material was prone to large residual stress and uneven deformation, which greatly affects the quality of the formed parts. All of the birth-death cell technique, the transient thermal model and the thermo-elasto-plastic model were adopted for the thermal process and residual stress simulation during the additive manufacturing process. The calculation results were used to study the effects of different deposition paths on the thermal cycle characteristics and residual stress distribution of TC4 part in plasma arc additive manufacturing. Meanwhile, the validation experiment was carried out to check the effectiveness of the finite element model through thermal tests. The simulated thermal curves match the experimental results well. The results show that both paths generate higher residual stress in the area around the arc-extinguishing point than the rest, and the zigzag with contour-offset path has better heat dissipation than the full zigzag path, and the residual stress of the deposited layer of the contour-offset path is significantly lower than that of the full raster path. Previous layers are subjected to a complicated thermal cycles, when the new layers are deposited on old layers. The peak temperature is increased from the bottom layer to the middle layer. As new layer is deposited on top, the transient stress distribution of parts changes regularly. Larger stress is located near the middle of the top layers and the area where the bottom meets the substrate, which is then maintained and gradually converted into residual stress within the part.

Keywords

• additive manufacturing
• tc4
• aircraft blade
• thermal history
• residual stress
• numerical simulation