Experimental and numerical study of the flaring process for Zircaloy tube end

The tube flaring process has been traditionally used to expand one end of a tube without changing its cross-sectional area. This process can be achieved by driving a rigid conical punches or arc profile punches with various diameters inserting into the tube end either mechanically or hydraulically, to obtain desirable expansion ratios. In this study, taking the Zircaloy-4 tubes with different textures as the samples, a three-dimensional (3D) finite element model is established to simulate the process of flaring and the reliability of the model has been validated by experiments. Via an integration method using the subroutine Vumat in the Abaqus/Explicit platform, the effect of punch parameter (E) on the forming quality of flared tube has been revealed. Besides, the analyses for the flaring load, wall thickness variation, stress–strain path, and texture evolution are also carried out via the experimentation and simulation. It is observed that the tube flared by the punch with E = 2.0 has a lower wall-thinning ratio so that the higher formability is achieved. To prevent the local bulking during flaring, the value of E with the range of 0 to 2.5 is reasonable. Furthermore, the relationship between strain ratio and texture evolution is constructed.