Mechanical material characterization and identification of forming parameters of AA2198-T3S1 aluminum-lithium alloy

Al-Li (Aluminum-Lithium) alloys have become the focus of the aerospace industry due to their low density and high elasticity modulus, excellent corrosion resistance, high hardness, high fatigue crack growth resistance, and low fracture toughness. In this thesis, it is aimed to determine the mechanical material characterization and forming parameters as a result of hydraulic forming with diaphragm, which is widely used among the sheet metal forming methods of AA2198-T3S1 material, which is one of the new generation Al-Li alloy classes. It is aimed to create a table containing the amount of spring-back and whether there is wrinkle, depending on the bending angle, bending radius and material thickness to be used as input in the company library. First, experimental studies were carried out. In the experiments, sheet metal with a thickness of 1.8mm and a die with bending angle of 60 °, 90° and 120 °, and with bendig radius of R0.5, R1, R2, R2.5, R3, R4, R5, R6, R6.35, R7.5, R8, R9, R10, R11, and R12.5 were used. No lubrication / nylon film is used between the sheet metal and the forming die. Then, the amount of spring-back was determined, and graphs showing the conditions and safe areas were created by comparing the experimental results with the finite element program for three different friction coefficient, 0.05, 0.1, and 0.2. With the data obtained as a result of this study, the loss of the time and the cost that may occur in production, and the scrap amaount of the sheet metal were prevented by designing dies that allow forming process safely in design changes.