EFFECT OF SAMPLE ORIENTATION ON STATIC RECRYSTALLIZATION OF AZ31 MAGNESIUM ALLOY

The effect of sample orientation on static recrystallization (SRX) of AZ31 magnesium alloy was investigated with electron backscattered diffraction (EBSD) technique. Two kinds of samples, one was cut along the normal direction of the sheet (0 degrees sample), the other along the transverse direction of the sheet (90 degrees sample), were given 15% uniaxial compression strain at 150 degrees C, followed by annealing at 275 degrees C for different times. The results show that slip dominates the deformation process during 15% uniaxial compression strain for the 0 degrees samples. However, extension twinning firstly dominates the deformation process and then slip dominates the deformation process during 15% uniaxial compression strain for the 90 degrees samples. Due to the different deformation mechanisms, the deformation stored energy of the 90 degrees samples is lower than that of the 0 degrees samples. As a result, the initiation and completion of SRX of the 90 degrees samples are significantly retarded compared with that of the 0 degrees samples. As SRX proceeds, the percentage of low angle grain boundaries between 2 degrees and 4 degrees decreases dramatically and a peak located around 30 degrees appears in misorientation angle distribution map for both the 90 degrees samples and the 0 degrees samples. Most SRX grains nucleate at the original grain boundaries for both the samples. A few SRX grains nucleate within extension twins.