Effects of extrusion parameters on tensile properties of magnesium alloy tubes fabricated via hydrostatic extrusion integrated with circular ECAP

To meet the need for high strength tubes for various industrial applications, a new method, known as hydrostatic extrusion integrated with circular equal channel angular pressing (HECCAP), was proposed for the fabrication of AZ80 magnesium alloy tubes. Small diameter billets could be extruded into tubes of larger diameters using this method. The effects of the extrusion ratio (ER) and the conical mandrel angle (CMA) on the microstructure and tensile properties of the AZ80 magnesium alloy tubewere investigated. The HECCAP-treated alloys exhibited a partial dynamically recrystallized microstructure. More shear zones formed inside of these grains, and a higher recrystallization grain volume fraction were presented in the alloy after HECCAP treatment with a larger ER or CMA values. The tensile yield strength, ultimate tensile strength, and elongation percent increased as ER and CMA also increase. The highest ultimate tensile strength, tensile yield strength and elongation were 335 MPa, 308 MPa, and 7.2%, respectively, at an ER of 2.77 and CMA of 120 degrees. A formula was proposed to calculate the total generated plastic strain after HECCAP, which increased with increasing ER and CMA. (C) 2016 Elsevier Ltd. All rights reserved.