Numerical and experimental investigation on the cross-wedge rolling of powder sintering TC4 alloy

Abstract

The application and demand of titanium alloys has been steadily increasing in aviation due to the excellent high-temperature performance. Powder metallurgy (PM) technology has been widely applied in the production of titanium alloy but with more disadvantages. The application of the cross-wedge rolling (CWR) process to manufacture powder sintering titanium alloy has received the least attention but is most significant. This paper presents a numerical and experimental study on the CWR of sintering TC4 alloy blade preforms. The deformation behavior of sintering TC4 alloy was investigated, and a constitutive equation at peak stress was developed and implemented into a finite element (FE) model, by which we analyzed the effect of tool parameters, forming quality, and forming mechanism in the CWR process. We also investigated the effect of the deformation temperature and area reduction on forming quality with CWR experiments. The results show that the deformation behavior of sintering TC4 alloy is sensitive to temperature and strain rate, and the constitutive equation is capable of predicting the flow stress for the CWR process. Among the tool parameters, area reduction is the most significant factor and showed the best performance at less than 65.9%. An applicable range of process parameters for the CWR of sintering TC4 alloy was obtained. After rolling, the relative density improves from 86.21 to 98.2%, and the mechanical properties of the workpiece are significantly enhanced, especially for elongation. Compared with 45# steel, the temperature difference in the radial direction (ΔT) of TC4 alloy is much larger due to a lower thermal conductivity. However, the rolling force and torque of TC4 alloy needed in the CWR process are only half as much as those of 45#.