(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙410083；
2. 中南大學(xué) 有色金屬材料科學(xué)與工程教育部重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙410083)
摘 要: 對(duì)AZ31鎂合金熱軋板材在423 K進(jìn)行6道次雙向反復(fù)彎曲變形，隨后在523 K退火1 000 s，利用光學(xué)顯微鏡和電子背散射衍射(EBSD)技術(shù)研究該工藝過(guò)程中組織及織構(gòu)的演變規(guī)律。結(jié)果表明：孿生是主要變形機(jī)制；在523 K退火1 000 s后，邊部組織已經(jīng)完全靜態(tài)再結(jié)晶，晶粒明顯細(xì)化，而中部組織僅發(fā)生晶粒長(zhǎng)大，最終形成兩邊晶粒細(xì)小、中間晶粒粗大的雙向梯度組織。退火態(tài)樣品內(nèi)部織構(gòu)得到弱化，從板材幾何中心處至兩表面，織構(gòu)強(qiáng)度逐漸降低，沿板厚方向呈不嚴(yán)格的對(duì)稱(chēng)梯度分布；靠近板材上表面區(qū)域織構(gòu)發(fā)生弱化和隨機(jī)化，靠近板材下表面區(qū)域晶粒取向集中在取向因子為0.5的方向，而板材幾何中心處僅部分晶粒取向發(fā)生偏轉(zhuǎn)，取向因子呈雙峰分布。
關(guān)鍵字: 鎂合金；雙向反復(fù)彎曲；孿晶；晶粒細(xì)化；織構(gòu)弱化
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China）
Abstract:The microstructure and texture evolution in the sheets of AZ31 Mg alloy was studied by bidirectional cyclic bending for 6 passes at 423 K followed by annealing at 523 K for 1 000 s. The deformed and subsequent annealed microstructures were investigated by optical microscopy and EBSD techniques. The results show that twinning is the main deformation mechanism. After annealing at 523 K for 1 000 s, the grains near the surfaces have full recrystallization. Thus, they are obviously refined. But the grains in the middle of the sheet just grow up. Finally, a gradient structure with fine grains in the regions near the surfaces and, in contrast, the coarse grains in the center of the sheet are induced. The texture in the annealed sample is weakened. The texture intensity decreases gradually from the center of the sheet to the surfaces, and has a relaxed gradient distribution along the thickness direction. The texture of the regions near the upper surface is weakened and randomized. Near the lower surface, the crystal orientation focuses on the direction that Schmid factor is 0.5. However, only a few grains tilt in the center of the sheet, in which the Schmid factor has a bimodal distribution.
Key words: magnesium alloy; bidirectional cyclic bending; twin; grain refinement; texture weakening
