(1. 重慶大學(xué) 材料科學(xué)與工程學(xué)院，重慶 400081； 2. 貴州大學(xué) 材料與冶金學(xué)院，貴陽(yáng) 550025； 3. 貴州省材料結(jié)構(gòu)與強(qiáng)度重點(diǎn)實(shí)驗(yàn)室，貴陽(yáng) 550025)
摘 要: 對(duì)AZ31鎂合金軋制態(tài)板材分別在473~673 K溫度范圍退火1 h以獲得不同初始顯微組織。通過(guò)金相顯微鏡、背散射電子衍射分析(EBSD)和力學(xué)試驗(yàn)機(jī)，研究晶粒尺寸和取向分布對(duì)合金板材室溫單向靜拉伸過(guò)程塑性變形和斷裂機(jī)制的影響。結(jié)果表明，晶界取向角呈連續(xù)分布有利于晶粒協(xié)調(diào)塑性變形。隨著晶粒尺寸的降低，晶界對(duì)室溫塑性變形的貢獻(xiàn)增大，晶界與位錯(cuò)滑移和孿生的交互作用增強(qiáng)。對(duì)于取向角均呈連續(xù)分布的473 K和573 K退火態(tài)板材，平均晶粒尺寸分別為3.6 μm和9.5 μm，塑性變形主導(dǎo)機(jī)制由晶界滑動(dòng)和位錯(cuò)滑移轉(zhuǎn)變?yōu)榫Ы缁瑒?dòng)、位錯(cuò)滑移和孿生，斷裂機(jī)制由微孔聚集型轉(zhuǎn)變?yōu)槲⒖拙奂秃徒饫硇突旌闲蛿嗔逊绞健?73 K退火態(tài)板材的平均晶粒尺寸達(dá)22.9 μm，塑性變形主導(dǎo)機(jī)制為位錯(cuò)滑移和孿生。此時(shí)，由于晶界取向角呈離散分布，晶粒協(xié)調(diào)塑性變形能力差，斷裂機(jī)制轉(zhuǎn)變?yōu)榻饫頂嗔选?/span>
關(guān)鍵字: AZ31合金軋制板材；晶粒尺寸；取向；塑性變形；斷裂機(jī)制
（1. College of Materials Science and Engineering, Chongqing University, Chongqing 400081, China; 2. School of Materials and Metallurgy, Guizhou University, Guiyang 550025, China; 3. The Key Laboratory for Mechanical behavior and Microstructure of Materials, Guiyang 550025, China）
Abstract:Different initial grain sizes and misorientation of AZ31 alloy sheets were obtained by different annealing temperatures of 473-673 K for 1 h, respectively. The mechanisms of plastic deformation and fracture were investigated by optical microscope, EBSD and tensile test with strain rate of 1×10-3 s-1 at room temperature. The results show that the continuous distribution of grain boundary misorientation angle(GBMA) inclines to improve the ability of grain coordination plastic deformation. With decreasing grain sizes, the contribution of grain boundary on plastic deformation at room temperature increases for improving the interaction between grain boundary sliding(GBS) and dislocation slipping(DS) as well as twinning. As for the alloy sheets annealed at 473 K and 573 K, which present the mean grain sizes of about 3.6 μm and 9.5 μm with continuous distribution of GBMA in both, the mechanism of plastic deformation transforms from the domination of interaction of GBS and DS to that of GBS, DS and twinning. And the fracture mechanism transforms from the micropore aggregation fracture to the mixture fracture, combining with micropore aggregation and cleavage. While as for the sheet annealed at 673 K, characterized by the average grain size of about 22.9 μm and disperse distribution of GBMA, the mechanism of plastic deformation is dominated by DS and twinning, and the fracture mechanism changes into cleavage fracture for the poor ability of grain coordination plastic deformation.
Key words: as rolled AZ31 alloy sheet; grain size; misorientation; plastic deformation; fracture mechanism
