SIMULATION AND EXPERIMENT ON WARM HYDROFORMING OF AZ31 MAGNESIUM ALLOY TUBE

The wrinkling behavior of an AZ31B magnesium alloy tube was investigated by simulation at different loading paths and at different temperatures. The effects of strain rate, internal pressure and temperature on the wrinkles were studied. Stressstrain track was analyzed in the quasi-static strain state graph of the plane stress processing to explain the changing of the wrinkles' shape, radius and wall thickness. It is shown that shape of the wrinkles wave along the axial direction keeps the sine wave character. The radius and thinning at the top zone of the wrinkles and the width of the wrinkles increased with the temperature, the internal pressure or the axial feeding. Moreover, hydro-formability of wrinkled parts was investigated and the improvement was observed. Finnally, as an application of using wrinkled parts as preform prior to the final calibration, a magnesium alloy tubular part with 50% expansion ratio was formed.