合肥工业大学 a. 材料科学与工程学院； b. 工业与装备技术研究院， 合肥 230009
发布日期:2019-12-11通讯作者:薛克敏(1963-)，男，教授，博士生导师，电话（Tel.）: 0551-62905110；E-mail：xuekm@hfut.edu.cn.作者简介:李萍(1973-)，女，黑龙江省哈尔滨市人，教授，博士生导师，主要研究方向为精密塑性成形工艺及组织性能.基金资助:国家自然科学基金资助项目（51575153）Microstructure and Mechanical Properties of 7A60 Aluminum Alloy by Friction Stir Processing
LI Ping a,ZHANG Kai b,WANG Boxiaotian a,XUE Kemin aa. School of Materials Science and Engineering; b. Institute of Industry and Equipment Technology, Hefei University of Technology, Hefei 230009, China
Published:2019-12-11摘要/Abstract
摘要： 以7A60铝合金为研究对象，采用搅拌摩擦加工(Friction Stir Processing, FSP)技术对其进行塑性改性并探索加工参数对7A60铝合金组织及力学性能的影响.结果表明：搅拌摩擦加工过程中铝合金发生动态再结晶而形成细小均匀的等轴晶；基体中第二相破碎细化，均匀分布在基体中且组织中η(MgZn2)相发生回溶；速比因子在很大程度上影响合金性能，随着速比因子的增大，搅拌区硬度先增加后减小.当速比因子为5时，材料显微硬度和抗拉强度达到最高(维氏硬度约120，抗拉强度 449.9MPa)，相比母材分别提高 37.5% 和 35.5%；速比因子继续增大时，搅拌头产热量急剧增加，导致材料组织严重粗化且拉伸断口韧窝变浅，使得材料强度和塑性降低.
关键词: 搅拌摩擦加工； 7A60铝合金； 显微组织； 力学性能
Abstract: Friction stir processing (FSP) were carried out to modify the mechanical properties of 7A60 aluminum alloy. The effect of friction stir processing parameters on the microstructure and mechanical properties of 7A60 aluminum alloy were investigated. The results showed that the uniform and fine equiaxed grains were formed due to dynamic recrystallization and the second phases were refined by severe plastic deformation with homogeneous distribution in the Al matrix. Meanwhile the content of η (MgZn2) phase decreased under the action of FSP heat, indicating the occurrence of the dissolution of η(MgZn2) phase into the Al matrix. Velocity ratio factor (ω/v) was a decisive impact factor of the mechanical performance of the nugget zone. With the increase of ω/v, the microhardness of the FSP-processed sample firstly increased and then decreased. The highest Vickers hardness was 120, which was 37.5% higher than the base metal, was obtained when ω/v reached 5, and the tensile strength increased to 449.9MPa. With the increase of ω/v, more heat produced by the stirring head led to significant grain coarsening and the dimples of the tensile specimens fractography become shallow, which in turn severely affected the tensile strength and plasticity of the material.
Key words: friction stiring processing (FSP); 7A60 aluminum alloy; microstructure; mechanical properties
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