New rotary piercing process for an AZ31 magnesium alloy seamless tube

To address the existing defects in the processing of magnesium alloy seamless tubes (MASTs), a new technology for producing AZ31 alloy tubes using a rotary piercing process was studied. Through the finite-element method and experimental analyses, the distributions of stress and strain and the temperature fields were analysed. The effects of temperature, radial reduction, plug diameter, and advance on the penetration rate, diameter, and wall thickness of the tube were studied. The results showed that temperature is the most important parameter; the penetration rate of the tube was > 90% for rolling temperatures of 350-450 degrees C. There was complete dynamic recrystallisation and a uniform distribution of equiaxed grains. This process can potentially replace the traditional extrusion process to produce MASTs.