Basal-Texture Induced Low Formability during Room Temperature Hydroforming of Fine-Grained AZ31 Mg Tubes

Abstract

The microstructures and mechanical properties of the AZ31 Mg tubes fabricated by one-pass forward piercing tube extrusion are examined. The grain size is refined from the initial ∼75 μm grain size down to 2—3 μm. The room temperature uniaxial tensile elongations, measured along an axis that is 0°, 45°, or 90° with respect to the extrusion direction, are satisfactory, ranging from 20 to 50%. However, room temperature tube hydroforming, under a more complicated stress state, results in poor formability as a result of the strong basal plane texture. Rationalization in terms of Schmid factor analysis on the data obtained from the pole figures yields consistent results. Solutions for such difficulty are proposed.