摘要
针对传统粗晶镁合金材料塑性差、成形精度低的问题,提出了超细晶镁合金电流辅助微成形新方法。利用高压扭转技术制备了平均晶粒尺寸约110 nm的超细晶AZ31镁合金,分别对粗晶和超细晶镁合金材料进行了电流辅助微拉伸变形行为研究,发现电流辅助下材料的流动应力明显降低,且相同条件下超细晶镁合金的抗拉强度较低,而伸长率较高。粗晶试样和超细晶试样的断口形貌明显不同,粗晶镁合金的变形不均匀,韧性断裂后产生局部熔断;超细晶镁合金变形均匀,从试样外表面形成裂纹后产生整体熔断。在此基础上,绘制了超细晶镁合金电流辅助微成形热加工图,结果表明,超细晶镁合金功率耗散效率更高,成形性能明显优于粗晶镁合金。
Aiming at the problems of poor plasticity and low forming accuracy of traditional coarse-grained magnesium alloy materials,a novel electrically-assisted(EA)micro-forming method is proposed using ultrafine-grained(UFG)magnesium alloy.The UFG magnesium alloy with an average grain size of~110 nm were prepared using high-pressure torsion(HPT).The deformation behavior of electrically-assisted micro-tension using coarse-grained(CG)and UFG samples were studied respectively.The results indicate that the flow stress of both CG and UFG magnesium alloy decreases obviously when applying currents.Compared with CG magnesium alloy,the UFG magnesium alloy exhibits lower tensile strength and higher elongation under the same conditions.The results of fracture morphology observation show that there are obvious differences between CG and UFG magnesium alloy.The deformation of the CG magnesium alloy is uneven and the partial fusing occurs after ductile fracture,while the deformation of UFG magnesium alloy is more uniform,and the overall fusing occurs after the formation of cracks from the outer surface of the sample.On this basis,an EA micro-forming thermal processing map of UFG magnesium alloy was constructed.The results show that UFG magnesium alloy has higher power dissipation efficiency and its forming performance is significantly better than that of CG magnesium alloy.
作者
虞钧
陈万吉
徐杰
单德彬
郭斌
YU Jun;CHEN Wanji;XU Jie;SHAN Debin;GUO Bin(Key Laboratory of Microsystems and Microstructures Manufacturing of Ministry of Education,Harbin Institute of Technology,Harbin 150080;School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2022年第16期68-76,共9页
Journal of Mechanical Engineering
基金
国家自然科学基金资助项目(51375111,51475124)
关键词
微成形
电致塑性
超细晶
高压扭转
镁合金
micro-forming
electroplasticity
ultrafine grains
high-pressure torsion
magnesium alloy
