Effect of Different Pulse Current Parameters on the Formability of 2A97-T3 Al-Li Alloy

Abstract

The Al-Li alloy has the advantages of low density, high specific strength, good weldability, good fracture toughness, strong fatigue crack propagation resistance, and excellent corrosion resistance. However, the plasticity of Al-Li alloy is poor at room temperature, so it formability is not ideal. In order to solve the problem, the electric pulse-assisted forming test is carried out on the 2A97-T3 Al-Li alloy to explore the forming properties. The mechanism of the forming perfoemance is revealed by the stress-strain curve macroscopically and the microstructure morphology microscopically. The results show that the Joule heating effect and the electron wind effect are generated in electric pulse-assisted forming. As a result, the yield strength and the tensile strength of the 2A97-T3 Al-Li alloy are significantly reduced. The Joule heating effect is enhanced due to the large pulse current intensity at the necking part, which can easily cause overburning. The grain size increases due to overburning. The elongation at break decreases significantly. After conducting a certain number of electric pulse-assisted forming tests, the appropriate processing parameters are obtained as follows: the pulse current intensity is 450 A, the duty cycle is 60.0%, the frequency is 50 Hz, and the forming rate is 0.001 s⁻¹. The yield strength of Al-Li alloy is 89 MPa, and the elongation to fracture is 13.2% under that condition. The formability is obviously improved. Besides, the dynamic recovery and the dynamic recrystallization of the alloy occur.