A new process chain combining cross-wedge rolling and isothermal forging for the forming of titanium alloy turbine blades

Abstract

Titanium alloy blades are significantly important parts for aero-engine, and their special outline and production status requires an efficient and low-cost production process. In this paper, a new sequence for forming the titanium alloy blade using cross-wedge rolling (CWR) and isothermal forging was proposed. A finite element (FE) numerical model which contains the entire sequence, including the transfer process, CWR process, and isothermal forging process, was developed. And the axial displacement, strain-stress state, and temperature variation were analyzed based on its material properties of titanium alloy. The results showed that the billet experiences a smooth flowing in the center along the axial direction, and no large concavity occurs due to the higher viscosity. Moreover, the chilling effect of the dies was effectively counterbalanced by the deformation-heat near the surface, and there is no larger temperature difference. During the isothermal forging, the flash is symmetrically distributed around the fully filled blade and no obvious forming defects occur. Moreover, the novel sequence contributes to improving the deformed microstructure by accelerating the globularization of the long-strip alpha phase and increasing the volume fraction of the primary alpha phase. The technical feasibility of the novel sequence was verified by the corresponding experiments.