IOSR Journal of Engineering (IOSRJEN) www.iosrjen.org ISSN (e): 2250-3021, ISSN (p): 2278-8719 Vol. 08, Issue 9 (September. 2018), ||V (III) || PP 36-45 International organization of Scientific Research 36 | P a g e Microstructuralevolution and mechanical behavior during annealing of aluminum deformed by equal channel angular pressing Rachel Santos Mendes 1,* ,Ana Carolina Ribeiro Duarte 1 , Fabiane Roberta Freitas Da Silva 1 , Jefferson Fabrício Cardoso Lins 1 1 Programa de Pós Graduação em Engenharia Metalúrgica, Universidade Federal Fluminense, 27255-125, Volta Redonda, RJ, Brazil Corresponding Author: Rachel Santos Mendes1 Abstract: This study aims to characterize the microstructure and the evolution of the mechanical behavior after annealing of the AA1070 aluminum alloy cold pressed equal angular channels. The deformation was conducted via route A in five consecutive passes and the accumulated deformation was 5.95. The annealing was carried out at 200 ° C and 250 ° C for 5, 10, 15, 20, 25, 30, 45, 60 minutes. The starting material was derived from a slab of 610 mm thick chopped in multiple passes through hot rolling to final thickness of 32 mm. The microstructure of the material was characterized with the aid of scanning electron microscopy (SEM) in the secondary electron mode. Vickers hardness tests were conducted in order to evaluate the mechanical behavior of the material after pressing and along the heat treatment. The final gran sizes were 1.91μm and 2.07μm ate 200ºC and 250ºC, respectively. The microstructure morphology evolved to near equiaxial. After five consecutive passes of ECAP deformation the average hardness measured was 48.2. The final hardness values after annealing at 200 ° C and 250 ° C were 44.7 Vickers and 40.1Vickers. The reduction at the end of the heat treatment was 7% for the temperature of 200 ° C and 14% for the temperature of 250 ° C. The softening throughout the heat treatment times was due to the activation of the recovery and recrystallization mechanisms that led to changes in the microstructure in order to form a lower energy configuration. The analysis of hardness maps constructed from the data of the mechanical tests allowed concluding that the thermal treatment lead to a development of homogeneity of the hardness distribution. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 08-09-2018 Date of acceptance: 24-09-2018 ----------------------------------------------------------------------------------------------------------------------------------- I. INTRODUCTION The mechanical and physical properties of polycrystalline materials are determined by several factors. Grain size is often the factor that influences it in a significant and dominant way. Thus, controlling grain size is one of the methods to produce materials with desired properties and to improve the existing ones. For this reason, ultrafine materials have been of great interest to the scientific community in recent decades [1,2].Severe plastic deformation (DPS) has shown to be promising for this purpose. SPD can be described as a metal forming technique in which the granular structure of the material is refined by the introduction of large plastic deformations. The equal channel angular pressing (ECAP) is considered by the literature as one of the most efficient SPD techniques [3]. Many researchers are currently focusing their efforts on elucidating the mechanisms responsible for grain refinement as well as evaluating the evolution of the anisotropic properties of severely deformed materials at room temperature. Consequently, there are few studies in the literature on thermal stability and the behavior of these materials against annealing [4].When a metal is severely deformed there is an increase in the amount of the stored energy. This increase is associated with the amount of crystalline defects generated in the microstructure during the deformation process.Under these conditions, the microstructure is thermal and mechanically unstable. And it can be easily modified by the dynamic recovery and dynamic recrystallization phenomena, in case of the material is subjected to a critical load even at room temperature. This condition is one of the most critical problems for the practical engineering applications of severely deformed materials and the annealing treatment has proved to be efficient in reducing these instabilities. However, it is difficult reducing instabilities and maintaining excellent mechanical properties at the same time. Thus, studies have been devoted to establishthe adequate annealing time and temperature [5]. In this context, this study analyzed the evolution of the mechanical behavior of the aluminum alloy AA1070 deformed in ECAP via route A and annealed at 200ºC and 250ºC. The microstructural characterization was carried out by MEV and EBSD.The mechanical behavior and its evolution were evaluated by Vickers hardness.