Influence of thermally activated processes on the deformation behavior during low temperature ECAP

18th Chemnitz Seminar on Materials Engineering – 18. Werkstofftechnisches Kolloquium

Fritsch, S.^1 ; Scholze, M.^1 ; Wagner, M.F.-X.^1

Department of Materials Science, Institute of Materials Science and Engineering, Technische Universität Chemnitz, Chemnitz

09215, Germany^1

关键词: Deformation temperatures;    High strength aluminum alloys;    Low temperature deformations;    Microstructural changes;    Severe plastic deformations;    Strain hardening rate;    Thermally activated process;    Ultra fine grained microstructure;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/118/1/012030/pdf
DOI  :  10.1088/1757-899X/118/1/012030

来源: IOP

【 摘 要 】

High strength aluminum alloys are generally hard to deform. Therefore, the application of conventional severe plastic deformation methods to generate ultrafine-grained microstructures and to further increase strength is considerably limited. In this study, we consider low temperature deformation in a custom-built, cooled equal channel angular pressing (ECAP) tool (internal angle 90°) as an alternative approach to severely plastically deform a 7075 aluminum alloy. To document the maximum improvement of mechanical properties, these alloys are initially deformed from a solid solution heat-treated condition. We characterize the mechanical behavior and the microstructure of the coarse grained initial material at different low temperatures, and we analyze how a tendency for the PLC effect and the strain-hardening rate affect the formability during subsequent severe plastic deformation at low temperatures. We then discuss how the deformation temperature and velocity influence the occurrence of PLC effects and the homogeneity of the deformed ECAP billets. Besides the mechanical properties and these microstructural changes, we discuss technologically relevant processing parameters (such as pressing forces) and practical limitations, as well as changes in fracture behavior of the low temperature deformed materials as a function of deformation temperature.