امين بچاري

Abstract: In this study, the effect of the warm Equal Channel Angular Pressing (ECAP) process on the mechanical properties, hardness, and microstructure of the Al-6Mg alloy was investigated. The primary objective was to enhance the mechanical properties of this alloy through the application of severe plastic deformation and post-ECAP annealing. Samples were eva‎luated after one, three, and five passes of ECAP, followed by annealing at temperatures ranging from 150°C to 250°C. The results demonstrated that the five-pass sample annealed at 150°C exhibited the best mechanical properties, including high ultimate tensile strength, suitable toughness, and optimal elongation, due to the occurrence of dynamic recrystallization and controlled recovery. The yield strength increased by 136% and the ultimate tensile strength by 202%, reaching 208 MPa and 341 MPa, respectively. The percentage of elongation also increased by 338.7% to 13.6%, with toughness measured at 30.23 MJ/m³. The improvement in mechanical properties was attributed to the increase in dislocation density and changes in grain size. In contrast, the three-pass sample annealed at 150°C showed the weakest mechanical properties. Optical microscopy revealed that with an increasing number of passes, the grain structure became finer and more uniform. Additionally, the microstructure was examined using Scanning Electron Microscopy (SEM). In the annealed samples, grain growth was observed at higher temperatures, leading to reduced toughness and elongation. Hardness measurements indicated that the three-pass sample exhibited the highest hardness at both 150°C and 250°C. As the annealing temperature increased from 150°C to 250°C, a decrease in elongation and toughness was observed due to grain growth and changes in grain size. This growth reduced the material's resistance to plastic deformation and lowered mechanical properties. Furthermore, dynamic recovery at higher temperatures resulted in a decrease in dislocation density, leading to reduced hardness and toughness. Therefore, the selection of an appropriate annealing temperature and the optimal number of passes plays a crucial role in achieving a homogeneous microstructure and desirable mechanical properties.

فشار در كانال زاويه يكسان، تعداد پاس، دماي آنيل، ريزساختار، خواص مكانيكي، آلياژ Al-6Mg

ECAP, Annealing temperature, Number of passes, Microstructure, Mechanical properties, Al-6Mg alloy

Amin Bachari

Dr. H.R.Jafarian