摘要
提出一种集镦粗、剪切和挤压变形于一体的膨胀不等通道转角挤压法(expansion non-equal channel angular extrusion,Exp-NECAE),基于理论分析,采用数值模拟与实验验证相结合的方法,研究多效应耦合作用下工业纯铝剧烈塑性变形行为,探讨分析变形材料对微观组织和力学性能的演变规律。结果表明,Exp-NECAE工艺具有高效率复合成形特点,坯料的变形过程连续、稳定、协调,可分为转角区变形、过渡区变形和完全挤出变形3个不同阶段;变形时材料内部处于理想的三向压应力状态,变形均匀性良好,单道次累积应变量高达2.56,接近理论计算值。1道次Exp-NECAE变形后,在镦-剪-挤耦合简单剪切应变诱导下,工业纯铝晶粒破碎和细化十分明显,材料内部形成了以细小等轴晶为主的混晶组织,平均晶粒尺寸约为2.73μm。同时,材料力学性能提升显著,平均显微硬度(HV)为558 MPa,抗拉强度为161.2 MPa,伸长率为13.9%。断口形貌中存在大量小而深的韧窝,且分布较为均匀,表现出了良好的韧性断裂的特征。
A novel process named expansion non-equal channel angular extrusion(Exp-NECAE) is proposed, which integrates various deformations including upsetting, shearing and extrusion in a single pass. Based on the theoretical analysis, severe plastic deformation behavior of commercially pure aluminum under multi-deformation coupling effects was investigated by numerical simulation and experimental verification, and the evolution of microstructure and mechanical properties of the processed materials was discussed. The results show that Exp-NECAE process has the advantage of high efficiency compound forming, the billet is extruded continuously, stably and compatibly, and the deformation process can be classified into three different stages: corner area deformation, transition area deformation and extruded area deformation. During the process, the processed material is in an ideal three-dimensional compressive stress state with homogeneous deformation distribution. The accumulative strain is as high as 2.56 after a single pass of extrusion, which is close to the theoretical calculation. After one pass of Exp-NECAE, under the simple shear strain induced by the coupling effects of upsetting,shear and extrusion, the grain size of commercially pure aluminum is significantly refined, forming a mixed microstructure dominated by ultrafine equiaxed grains with an average grain size of around 2.73 μm. Moreover, the mechanical properties of the processed material are significantly improved. The average microhardness(HV) is 558 MPa, and the tensile strength and the elongation can reach up to 161.2 MPa and 13.9%, respectively. A large number of small and deep dimples are observed in the fracture morphology, and the distribution is relatively uniform, showing a good ductile fracture characteristics.
作者
王晓溪
张翔
袁峻池
董兴兵
井新宇
张磊
Wang Xiaoxi;Zhang Xiang;Yuan Junchi;Dong Xingbing;Jing Xinyu;Zhang Lei(School of Mechanical&Electrical Engineering,Xuzhou University of Technology,Xuzhou 221018,China;Jiangsu XCMG Construction Machinery Research Institute Co.,Ltd,Xuzhou 221004,China;State Key Laboratory of Intelligent Manufacturing of Advanced Construction Machinery,Xuzhou 221004,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2021年第9期3176-3183,共8页
Rare Metal Materials and Engineering
基金
国家自然科学基金青年科学基金(51905462)
江苏省自然科学基金面上项目(BK20201150)
江苏省“六大人才高峰”高层次人才选拔培养资助项目(GDZB-127)
江苏省高等学校自然科学研究重大项目(19KJA140002)。
关键词
膨胀不等通道转角挤压
数值模拟
应变累积
晶粒细化
力学性能
expansion non-equal channel angular extrusion(Exp-NECAE)
finite element simulation
strain accumulation
grain refinement
mechanical properties
