Enhanced formability of interstitial free iron at high strain rates

The effect of induced electro-pulsing of 7075 aluminum alloy in solid solution and pre-deformation was studied. The tensile test results show that material plasticity is recovered and strength is increased by induced electro-pulsing treatment (IEPT). As the discharge time increases, the increase in elongation becomes more obvious. Yield strength, tensile strength, and elongation of once-treated samples increased by 3.7%, 1.3%, and 9.7%, respectively, compared with the untreated sample; Those of twice-treated samples increased by 6.4%, 6.4%, and 27.8%. Microstructure characterization showed that the induced current reduces the dislocation density of the material and promotes advanced precipitation of Guinier-Preston (GP) zones. In addition, the strength of treated samples and untreated samples was almost the same after peak aging treatment, while the elongation increased by 12.15%. High resolution transmission electron microscopy (HRTEM) images show that the size of the η’ phase in the treated alloy is smaller and the alloy exhibits better ductility.