Study on process parameters optimization of 7075-T6 aluminum alloy under contact heating

To solve the problem of poor formability of 7075-T6 aluminum alloy at room temperature and the degradation of properties after conventional warm forming, this paper put forward the contact heating warm forming (CHWF) process, which can make aluminum alloy blank reach the forming temperature in a very short time through the heated plates with pressure. Firstly, the uniaxial warm tensile tests with contact heating were carried out at 160-240 degrees C. Then the parameters of CHWF, namely forming temperature, contact pressure and holding time, were optimized based on the response surface and genetic algorithm. The U-shaped parts were obtained by using the optimal parameters. The results showed that the work hardening and dynamic recovery softening of 7075-T6 aluminum alloy at 200 degrees C could reach an equilibrium state, and the uniform plastic deformation ability was strong. The optimal parameters of CHWF were the forming temperature of 200 degrees C, the contact pressure of 10 MPa, and the holding time of 16 s. The U-shaped parts obtained by the optimal process had a small springback angle. Compared with the warm forming by using heating furnace, eta ' precipitate did not grow significantly under CHWF condition and the hardness could reach 93% of T6 state.