(1. 沈陽航空航天大學(xué) 材料科學(xué)與工程學(xué)院，沈陽 110036；
2. 中國科學(xué)院 金屬研究所，沈陽 110016)
摘 要: 室溫下對鎂合金擠壓棒材進(jìn)行了最大扭轉(zhuǎn)角分別為90°、180°和320°的扭轉(zhuǎn)變形，依據(jù)扭轉(zhuǎn)變形過程數(shù)值模擬結(jié)果，基于切應(yīng)力作用下的等效施密特因子計(jì)算模型，結(jié)合扭轉(zhuǎn)變形后晶粒取向的EBSD測試結(jié)果，對扭轉(zhuǎn)過程中的拉伸孿晶啟動機(jī)制進(jìn)行了分析。結(jié)果表明：在大扭轉(zhuǎn)角條件下，多數(shù)拉伸孿晶的啟動遵循Schmid定律，一些Schmid因子值低的拉伸孿晶也啟動。原始棒材中的晶粒c軸垂直于棒材軸向，而拉伸孿晶的啟動使多數(shù)晶粒的c軸向轉(zhuǎn)向平行于棒材軸向。晶粒中雖然啟動較多孿晶帶，但孿晶啟動并沒有改變扭轉(zhuǎn)變形過程中應(yīng)力應(yīng)變曲線的硬化特征，扭轉(zhuǎn)變形后棒材中仍保持為晶粒的基面平行于棒材軸向的織構(gòu)特征。
關(guān)鍵字: 鎂合金棒材；扭轉(zhuǎn)；拉伸孿晶；施密特因子
（1. School of Materials Science and Engineering, Shenyang Aerospace University, Shenyang 110036, China;
2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:Magnesium alloy rods were separately twisted to 90°, 180° and 320° angles at room temperature, according to numeric simulation results of torsions, based on mathematic model of effective Schmid factor under condition of shear stress loading, combined with EBSD measured results of grains orientation after torsion, the twinning mechanism during magnesium alloy torsion was analyzed. The analysis results show that activations of the most extension twins obey the Schmid criterion, and some extension twins with lower Schmid factors also activate. The c-axes of grains in origin rods are vertical to the axis of rods, and they are tilted to parallel to the axis of rods after extension twin activations. The hardening characteristic of stress-strain curves of torsions is not changed although many twin bands formed in grains. The texture of grains basal parallel to the axis of rods are maintained after torsion.
Key words: magnesium alloy rods; torsion; extension twin; Schmid factor
