Numerical Study and Optimization of the Thermomechanical Procedure in Forging of Two-Phase Ti-6Al-4V Alloy for Artificial Hip Joint Implant

A multi-objective numerical optimization was used to study the forging process of a Ti-6Al-4V alloy in producing an artificial hip joint implant. The forging temperature was chosen in the Alpha-Beta two phase region around 900°C. In order to implement the numerical simulation, the Deform 3D commercial code was used. Response surface methodology (RSM) was considered and experiments based on various widths (w), thickness of flash (t), and billet diameter (d) were designed to find out the influences of these parameters on flash volume, filling rate and strain non-uniformity as the responses. Twenty numerical tests were implemented by finite element analysis (FEA), and the obtained results were used to optimize the forging process using RSM. To this end, the constants of constitutive and governing equations to FEA and the data of a published paper were applied. The optimized results were w = 8 mm, t = 1.73 mm, and d = 30 mm, for flash geometry and billet diameter, respectively. Finally, an FEA was conducted based on the optimized values, and the results were compared and discussed with those in the Noiyberg-Mokel model for verification.