摘要
目的 针对宽幅AZ31镁合金轧板在多道次热轧过程中因道次间重复补温引发的晶粒细化-粗化交替现象及混晶组织形成问题,揭示混晶组织在退火过程中的动态演变规律,阐明其对微观组织与力学性能的调控机制,为实现终轧板材组织性能的精准调控提供理论基础。方法 基于含多尺度晶粒、剪切带及孪晶的混晶组织试样,系统研究其在不同退火温度(170~300℃)和保温时间(0.5~3 h)下的演变行为,以及对轧板力学性能的影响规律。结果 当退火温度超过200℃时,混晶组织得到显著改善,材料组织均匀性提高。晶粒尺寸随退火时间的延长呈现先减小后增大的特征性演变趋势,且退火温度升高会强化这一趋势。在170~300℃温度范围内,退火温度主导拉伸强度,而保温时间主要影响塑性。最大伸长率出现在250℃-2 h条件下,达24.5%,这归因于充分的再结晶形核和孪晶显著减少的共同作用。在相同退火温度下,硬度多在1 h保温处理后达到峰值,这种非线性演变源于晶粒等轴化转变与孪晶演化行为的竞争机制。结论 通过合理选择退火温度和时间,可改善组织均匀性并平衡强度与塑性,为宽幅AZ31镁合金轧板的退火工艺优化提供重要参考。
The work aims to elucidate the dynamic evolution mechanisms of mixed-grain structures in AZ31 magnesium alloy sheets during annealing,to address the issue of alternating grain refinement and coarsening along with mixed-grain formation caused by repeated inter-pass reheating in conventional multi-pass hot rolling,clarify the influence of annealing on microstructure and mechanical properties,and provide a theoretical foundation for precise control of the final rolled sheet's performance.Based on mixed-grain samples containing multi-scale grains,shear bands,and twins,their microstructural evolution under varying annealing temperature(170-300 C)and holding periods(0.5-3 h)were systematically investigated.The corresponding effects on mechanical properties were analyzed.When the annealing temperature exceeded 200 C,the mixed-grain structure was significantly improved,enhancing microstructural homogeneity.The grain size demonstrated a characteristic evolution pattern of initial refinement followed by coarsening with prolonged annealing time,a trend that became more pronounced at elevated temperature.Within the 170-300 C range,annealing temperature dominated tensile strength,while the holding period primarily affected ductility.The maximum elongation(24.5%)occurred at 250 C-2 h,attributed to sufficient recrystallization nucleation and pronounced twin reduction.At fixed temperature,hardness typically peaked after 1 h.This nonlinear behavior stemmed from competing mechanisms between grain equiaxed transformation and twin evolution.Rational selection of annealing temperature and time can enhance microstructural uniformity and balance strength-ductility trade-offs,offering critical guidance for optimizing annealing processes in wide AZ31 magnesium alloy sheets.
作者
吴凤彪
吕航
刘欣燕
宁方坤
康小平
贾伟涛
WU Fengbiao;LYU Hang;LIU Xinyan;NING Fangkun;KANG Xiaoping;JIA Weitao(Shanxi Institute of Energy,Shanxi Jinzhong 030600,China;Taiyuan University of Science and Technology,Taiyuan 030024,China)
出处
《精密成形工程》
北大核心
2026年第2期226-235,共10页
Journal of Netshape Forming Engineering
基金
山西省高等学校科技创新项目(2022L608)
忻州市重点研发计划项目(20240106)
国家自然科学基金(52105388,52504420)。
关键词
镁合金
轧制
混晶组织
退火工艺
再结晶
力学性能
magnesium alloy
rolling
mixed-grain structure
annealing process
recrystallization
mechanical properties
