Research On Organization-Property Of Aluminum And Aluminum Alloy And Friction State During ECAP

Aluminum and aluminum alloys are indispensable basic raw materials for strategicemerging industries, the development of the defense industry and national economy,which are widely used in electricity, transportation, architecture, packaging, aerospaceand other fields. With the development of economy, it is necessary to obtain thealuminum and aluminum alloy with high strength and high performance. ECAP (EqualChannel Angular Pressing), as a preparation technique to obtain bulk metallic withultrafine-grained materials, has a wide range of applications in the field of preparationof materials. Therefore, the study of ECAP has important theoretical and practicalsignificance.The purpose of the paper is to study microstructure and properties of aluminumand aluminum alloy during ECAP, as well as the effects of strain friction on the loadand equivalent. Based on the industrial pure aluminum and the high-strength aluminumalloy7075, some researches about the organizational performance and frictionstate have been carried out in this thesis with the theoretical derivation, the physicalexperiments and the numerical simulation techniques(1) To take account of the friction factor, the squeeze pressure was resolvedthrough theoretical upper limit and slip-line method. By comparing the results in twosolving methods, it is concluded that the friction pressure is an important part of thesqueeze pressure, which affects the size of the load. Furthermore, the study provides thebasis for the follow-up study.(2) By the ECAP with room temperature, the macro-morphology andmicrostructure of industrial aluminum were compared and analyzed under differentpasses and paths, as well as the hardness distribution.(3) The simulation of ECAP for7075aluminum alloy was carried out at differentfriction factors. The load, deformation behavior, as well as effective stress and straindistribution were analyzed. The grain size was predicted, and the effect of friction factoron the deformation and microstructure of7075aluminum alloy was studied.(4) Different friction factors of mold surface zoning were set in the orthogonaldesign. The results show that the load was most affected by friction state of the A area.The maximum equivalent strain was significantly affected by frictional state of the threeregions, in which the region B was the most one.