锆合金热变形过程中的织构演变研究

Evolution of crystallographic texture of zirconium alloy during hot deformation

摘要:

本文选取了一种热轧退火态的锆合金板材沿着其板材法向(0°样品)及横向(90°样品)在700 ℃温度下以1/s应变速率进行压缩试验。利用电子背散射衍射(EBSD)技术对变形后样品的微观组织及织构进行表征,并利用粘塑性自洽模型(VPSC)确定了在低应变条件下的各滑移系及孪晶的相对开启量。微观组织揭示了在两种样品中均有动态再结晶的发生。再结晶晶粒的织构变化与变形晶粒的织构变化相似,表明了再结晶过程中的优先形核及长大过程不会影响织构的形成及变化。在0°样品中,基面滑移、柱面滑移和锥面滑移在变形初期阶段同时开启,但是在90°样品中,只有少量的锥面滑移在变形初期阶段开启。在90°样品中存在的高强度的<10-10>//RD 织构组分是由大量开启的柱面滑移造成的。此外,700 ℃温度下大量基面滑移的开启对织构形成起重要作用。

Abstract:

In this work, a hot-rolled and annealed Zr alloy plate with a composition of Zr-1.06Sn-0.36Nb-0.3Fe-0.1Cr-0.13O (wt. %) was compressed along normal direction (0° sample) and transverse direction (90° sample) at 700 ℃ at a strain rate of 1/s. The microstructures and microtextures were characterized by electron backscattered diffraction (EBSD) technique. Visco-plastic self-consistent (VPSC) model was applied to evaluate the activity of slip and twinning systems during deformation at low strain. Microstructure characterization revealed that dynamic recrystallization (DRX) occurs in the two samples. It is found that the texture of the recrystallized grains is similar to that of parent grains, and the preferred nucleation or growth is not in charge of the texture formation. In the 0° sample, all three slip modes (basal, prismatic and pyramidal slip) operate from the first stage of deformation, while a few amount of pyramidal slip is active in the 90° sample in the early stage of deformation. The high activity of prismatic slip results in an intensive <10-10>//RD texture component in the 90° sample. Moreover, predominant basal slip activity at 700 ℃ is necessary to simulate the observed deformed texture.