孪晶类型对AZ31镁合金静态再结晶的影响

Influence of twin types on static recrystallization of AZ31 magnesium alloy

对轧制下压方向平行和垂直晶粒c轴的两类板材进行150℃轧制(5%下压量)后,利用背散射电子衍射分析(EBSD)研究了轧制试样中不同类型的孪晶组织对静态再结晶的晶粒形核、微观组织及织构的演变的影响。结果表明:含有大量{1011-}-{1012-}双孪晶的样品中,二次孪生有效促进再结晶形核,显著细化晶粒。再结晶晶粒取向规律性不强,有效削弱基面织构。而含有大量{1012-}拉伸孪晶的样品,拉伸孪晶不能有效促进再结晶形核。退火过程中基体不断长大,当再结晶驱动力足够大时,基体会吞并周围拉伸孪晶,同时诱发织构改变,基体取向的织构逐渐增强,拉伸孪晶取向的织构逐步减弱。

Two types of samples with c-axis of grains nearly parallel and perpendicular to the thickness reduction direction were rolled at 150 ℃ （5% reduction） , respectively. Influence of twin types in roiled samples on nucleation of grains, microstructure and texture evolution during static recrystallization was investigated by using electron backscattered diffraction analysis （ EBSD）. The results show that, for the sample which contains large amount of { 10 11 } - { 10 12 } double twins, the contraction twins and double twins are the preferred sites for new grains nucleation, and grain size is refined effectively. The orientation of new grains are scattered to some extent and the basal texture is weaken after annealing. For sample with much { 10 1-2 } tension twin, the tension twins are not effective for nucleation of recrystallization grains. Besides, the matrix grows up continuously during annealing and swallows the thin extension twin lamellas when the driving force is large enough, which cannot refine the grain size. The texture of matrix orientation is strengthened while the texture with orientation of extension twins is weakened during annealing.