摘要
针对铝合金高温与室温变形过程微观组织易粗化与不均匀难题,通过对6061铝合金在不同温度下压缩变形试验,阐明了变形温度对合金微观组织与性能的影响,结合背向散射电子衍射等技术重点分析了超低温(-196℃)变形对合金组织细化规律与机制。试验结果表明,500℃高温下合金发生动态再结晶,平均晶粒尺寸约30μm;20℃室温下,变形机制以位错滑移为主,变形在施密特因子大的晶粒内优先发生,导致组织分布不均,平均晶粒尺寸约为8.57μm;-196℃超低温下,回复过程受到显著抑制,位错运动受点缺陷钉扎效应影响明显,同时亚晶界密度增加导致滑移系启动的临界分切应力增大,超低温条件下热激活作用减弱和Peierls力增加共同导致变形抗力显著提升。增强的变形抗力不仅促进了位错滑移的均匀分布,同时形成平直细长的滑移带,产生更大的平均取向差(≥15°),最终获得平均晶粒尺寸约为1.13μm的超细晶组织。研究结果为铝合金塑性变形过程中的晶粒细化机制提供了新的理论依据。
The challenges of microstructural coarsening and inhomogeneity during high-temperature and room-temperature deformation of aluminum alloys are addressed through compression tests of 6061 aluminum alloy at different temperatures.The influence of deformation temperature on microstructure and mechanical properties is elucidated,with a focus on grain refinement mechanisms under cryogenic conditions(-196℃)using electron backscatter diffraction.Experimental results show that dynamic recrystallization occurs at 500℃,producing an average grain size of approximately 30μm.At 20℃(room temperature),deformation is dominated by dislocation slip,preferentially in grains with high Schmid factors,resulting in inhomogeneous microstructures and an average grain size of 8.57μm.Under cryogenic deformation(-196℃),recovery processes are significantly suppressed,and dislocation motion is hindered by the pinning effect of point defects.The increased density of subgrain boundaries raises the critical resolved shear stress for slip system activation.Weakened thermal activation and enhanced Peierls forces under cryogenic conditions jointly increase deformation resistance.This resistance promotes uniform dislocation distribution and generates straight,elongated slip bands with higher average misorientation angles(≥15°),ultimately yielding an ultrafine-grained structure with an average grain size of 1.13μm.The findings provide new theoretical insights into grain refinement mechanisms during plastic deformation of aluminum alloys.
作者
符云帆
易幼平
黄始全
何海林
董非
FU Yunfan;YI Youping;HUANG Shiquan;HE Hailin;DONG Fei(Research Institute of Light Alloy,Central South University,Changsha 410083;State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,Changsha 410083)
出处
《机械工程学报》
北大核心
2025年第14期56-62,共7页
Journal of Mechanical Engineering
基金
国家自然科学基金(52375398)
湖南省十大技术攻关(2023GK1060)资助项目。
关键词
6061铝合金
超低温压缩变形
取向差
位错滑移
6061 aluminum alloy
ultra-low temperature compression deformation
misorientation
dislocation slip
作者简介
符云帆,男,1995年出生,博士研究生。主要研究方向为铝合金成形与组织性能调控。E-mail:fuyunfan2618@163.edu.cn;通信作者:黄始全,男,1982年出生,博士,教授,博士研究生导师。主要研究方向为轻质合金构件成形制造组织演化与变形控制。E-mail:huangshiquan@csu.edu.cn。
