Abstract: The rolling curve, which is defined as the instantaneous relationship between the radial and axial deformation degrees during the radial-axial ring rolling(RARR) process thus determines the deformation history and roll paths, plays an important role in the geometry precision and microstructure of the rolled ring, especially for rolling of difficult-to-deform materials such as titanium alloy and as-cast billet. A design method of rolling curves for radial-axial ring rolling process is proposed. The method can be used to design three kinds of rolling curves, namely the convex, linear and concave ones, for known sizes of ring product and ring blank. And then the effects of different rolling curves on the circularity and microstructure (mainly including phase volume fraction and grain size) uniformity of the rolled TC4 titanium alloy ring by finite element(FE) simulations are numerically revealed. The results show that：Compared with the linear rolling curve, the concave rolling curve contributes to increasing the circularity of the rolled ring; and the convex rolling curve contributes to improving the microstructure uniformity. So in order to combine the advantages of the concave and convex rolling curves, An “S” form rolling curve is designed which is helpful to obtain TC4 titanium alloy ring simultaneously having precise dimensions and favorable microstructure uniformity.

Key words: difficult-to-deform materials;radial-axial ring rolling;rolling curve design;microstructure uniformity