Hydroforming of Ti-6Al-4V Acetabular Cups

Abstract

The use of room-temperature hydroforming was investigated as a method for production of Ti-6Al-4V titanium alloy orthopedic acetabular cups. Hydroforming is rarer for titanium alloys than steel or aluminum, and because of material forming challenges, is usually done at temperatures in excess of 500°C. This adds to process complexity, and significantly to cost. A theoretical and experimental investigation was conducted to assess the practicality of forming Ti-6Al-4V sheet into required preforms through hydroforming at room temperature. Sheet hydroforming is thought to be beneficial from both a quality and cost perspective for typical production rates, and it has process flexibility that can accommodate difficult to form materials. This manuscript presents the design of a hydroforming process sequence that avoids flange wrinkling and produces small base radii, while controlling springback with a final high-pressure stage. A finite element model aided in process analysis, and accurately predicted failure and deformation. The resulting optimized process has been demonstrated to reliably cold hydroform Ti-6Al-4V into the desired geometry.