Validation of Math-based Process for Hydroforming Dual Phase Steel Tubes

Dual phase steels are becoming increasingly popular choices for automotive structural applications at General Motors (GM) due to their strength and relatively good formability. Coming with it is the challenge for the manufacturing processes to produce the desired product with consistency. At GM, math-based die engineering process has been a reliable tool for tube hydroforming formability with conventional steels. This paper presents a validation of this math-based process for bending and hydroforming dual phase steel tubes. Several grades of dual phase steel tubes and conventional mild steel tubes are used to hydroform an experimental part. Final part thickness, and dimensional springback are measured and compared with simulation predictions. The results demonstrate the validity of this math-based process for formability of dual phase steel tubes and the ability to predict springback directions and magnitude estimation.