Effects of geometrical size and structural feature on the shape-distortion behavior of hollow Ti-alloy blade fabricated by additive manufacturing process

Abstract

In the additive manufacturing (AM) process, metal powder can be directly used to produce metal components. Unfortunately, a large thermal gradient is developed during the AM process, which leads to the generation of residual stress and complex shape-distortions. In this study, the influence of the geometrical size and structural features of a hollow Ti-alloy blade prepared by the AM process on the shape-distortion behavior was systematically investigated using the three-dimensional (3D) blue-light scanning technology. The results indicated that the concentrated residual stress was developed on the surface of the blade. The compressive residual stress induced a bulging distortion, while the tensile residual stress resulted in denting distortion on the blade surfaces. When the blade height and torsion angle increased, the shape-distortion was aggravated owing to the accumulation of microscopic strain and the elevated temperature gradient. However, the shape-distortion mitigated when the wall thickness significantly increased or the stiffened plates were set within the blade cavities, owing to a strengthening structural constraint which inhibited the distortion behavior. In addition, a control method for the shape-distortion during AM process was able to implement based on the proper optimization of the geometrical sizes and structural features of complex 3D-printed components.