Effect of initial microstructure on static recrystallization of Mg-3Al-1Zn alloy

The effects of twin types on grain nucleation and texture evolution during static recrystallization were investigated. Three kinds of cylindrical samples were cut from an AZ31 magnesium alloy plate with their compression directions aligned 0 degrees, 45 degrees, and 90 degrees to the normal direction (ND), and they were referred as OND, 45ND and 90ND samples, respectively. The compression tests were conducted at room temperature with a strain of 16%, followed by an annealing at 250 degrees C for 3 min, 20 min and 60 min respectively. The effects of twin types in different samples on grain nucleation and texture evolution during static recrystallization were investigated with electron backscattered diffraction (EBSD) technology. The {10 - 11} - {10 - 12} double twinning was found to be the dominant deformation mechanism in OND and 90ND samples, while {10-12} tension twins and compression twins can be observed in some grains in 45ND sample. The {10-11} - {10-12} double twins are the preferred sites for new grain nucleation, and the {10-12} tensile twins are unfavorable for nucleation of static recrystallization. It is noteworthy that a tiny fraction of {10-11} and {10 - 13} compression twins can be nucleation sites for new grains. The sequence of recrystallized speed in the samples is: 90ND sample > OND sample > 45ND sample. The grain size can be refined effectively and the deformation texture becomes weaken during the static recrystallization. The misorientation angle between recrystallized grains and matrix is fluctuated from 20 degrees to 60 degrees, and this phenomenon is suggested to be related to the {10-11} - {10-12} double twins, {10-11} and {10-13} compression twins.