Tooling design–related spatial deformation behaviors and crystallographic texture evolution of high-strength Ti-3Al-2.5V tube in cold pilgering

Cold pilgering has been considered as the preferred rolling fabrication technology for difficult-to-deform tubular materials such as high-strength titanium alloy tubes. However, the tooling geometry may induce complex deformation and significantly influence crystallographic texture which is closely related to the dimension assuring and properties tailoring of tube products. In this study, taking high-strength Ti-3Al-2.5V tubes as the case material, the tooling design–related spatial deformation behaviors and crystallographic texture evolution of tube in cold pilgering are focused. A macro-meso scaled computation platform is established by combining the three-dimensional finite element (3D-FE) model with the viscoplastic self-consistent (VPSC) crystal plasticity model to predict both the inhomogeneous macrodeformation and microtexture evolution in cold pilgering. Two basic tooling parameters in pilgering, viz., E₁ representing exponent of roller groove curve and mandrel curve and E₂ representing exponent of groove clearance, are chosen as the design variables. The cold pilgering under different tooling parameters are simulated and analyzed. The results show that (1) The rolling force decreases with the increase of E₁ , while the effect of E₂ on the rolling force is not significant, and smaller E₁ and larger E₂ have advantage for preventing surface defects of the tube product; (2) The E₁ of 2.8 and E₂ of 2.0 are more conducive to the wall thinning–dominated deformation of tube; (3) Taking the contractile strain ratio (CSR) as an indicator for characterizing crystallographic texture–related mechanical properties, the appropriate values of E₁ and E₂ for desirable radial texture of tube product are obtained.