Superplasticity in high temperature magnesium alloy WE43

Severe plastic deformation of the magnesium alloy WE43 (Mg-4%Y-2.3%Nd-0.5%Zr) has been carried out by multi-axial forging (MAF) in order to refine the grain size from 25 µm to 6 µm. Deformation behaviour of the as-processed material has been investigated. Compression tests were carried out in the temperature range 250-450 °C and in the strain rate range 10−3-10 s−1. Strain-rate sensitivity values were calculated from the stress-strain curves. A high value of strain rate sensitivity was noticed in the temperature range 350-400 °C and the strain rate range 10−4-10−2 s−1, which indicated the possibility of superplastic forming after multi-axial forging. The superplastic behaviour of MAF processed samples was further investigated by carrying out tensile tests. An excellent superplastic elongation of 470% was obtained at the temperature 375 °C and strain rate 3*10−4 s−1. The material also exhibited superplasticity at higher strain rates at this temperature.