Abstrakt
The influence of two fabrication techniques cast and rolling on the deformation behaviour of Mg-3Al-1Zn (AZ31) alloys was investigated. The tensile tests were conducted over a wide temperature range of 25 and 300 degrees C at a constant strain rate.
The rolled (textured) samples exhibit a strong basal texture - the flow stress depends on the orientation of the tensile to the rolling direction. It is shown that the deformation behaviour of AZ31 alloy poly-crystals depends on their microstructure produced by processing and temperature.
The values of the yield stress, flow stress and maximum stress of the AZ31 sheets are significantly higher than those of the AZ31 cast alloy if samples are deformed at room temperature, whereas the difference in the stress values for both types of samples is insignificant if deformed at 300 degrees C. The plots of the strain hardening rate against flow stress for the AZ31 sheets indicate interactions between basal and non-basal dislocations.
The values of internal stress decrease with increasing deformation temperature, which indicates that recovery processes play an important role during deformation at higher temperatures. The activity of two deformation mechanisms is considered: (a) interaction between dislocations moving in basal and non-basal slip systems producing sessile and glide dislocations, which leads to hardening and (b) cross slip of dislocations through prismatic planes causing softening.