Corner forming of AZ61A magnesium alloy tube within warm hydroforming

The corners with small radii on cross sections are crucial for forming hydroformed components with polygonal sections. In this paper, warm hydroforming experiments of AZ61A magnesium alloy tubes were carried out to study the forming regularity of round corners by using a demonstration part with square sections. Effects of temperature on radius forming, thinning ratio distribution and microstructure were revealed and a component with relative outer corner radius of 3.0 was obtained by warm hydroforming at 240°C. The minimum thickness of the formed square section was located in the transition position between the corner and the straight wall. The thinning ratio of the round corner increased with the increase of forming temperature. Formability of the magnesium tube was improved by raising temperature under the effect of dynamic recrystallization at 240°C.