Mechanical property and formability of AZ31B extruded tube at elevated temperature

The mechanical properties of AZ31B magnesium alloy tube were tested by ring hoop tension test at different temperatures. The formability for tube hydroforming was also evaluated by free-expansion test. The results show that there exists a quick decrease of total elongation along hoop direction at the temperature range of 150-230°C, which is quite different from that along axial direction. The total elongation along hoop direction of welded tube is quite close to that of seamless tube until 230°C is reached. At higher temperature, the total elongation for seamless tube begins to increase while the value for welded tube continues to decrease. The maximum free expansion ratio of seamless tube increases considerably as temperature increases and reaches the maximum value of 30% at 170°C, then decreases quickly at higher temperature.