“…This approach is implemented to produce multilayer plates. However, the main challenge with both MDE and AE techniques is the bonding and adhesion between the stacked layers [ 37 ]. Fig.…”
Section: Spd Mechanismsmentioning
confidence: 99%
“…This modification applies high plastic strain to the sample achieving the desired plastic deformation. PSE can adjust the ratio of pure to simple shear by assuming the shape changes from square to rhombic by PSE deformation [ 37 ]. The most significant feature of this process is obtaining relatively large UFG samples without back pressure nor sample rotation [ 38 ].…”
“…This approach is implemented to produce multilayer plates. However, the main challenge with both MDE and AE techniques is the bonding and adhesion between the stacked layers [ 37 ]. Fig.…”
Section: Spd Mechanismsmentioning
confidence: 99%
“…This modification applies high plastic strain to the sample achieving the desired plastic deformation. PSE can adjust the ratio of pure to simple shear by assuming the shape changes from square to rhombic by PSE deformation [ 37 ]. The most significant feature of this process is obtaining relatively large UFG samples without back pressure nor sample rotation [ 38 ].…”
“…There are increased requirements for physical and mechanical properties of bulk workpieces made of aluminium alloys, which are used for the production of parts operating under high cyclic bending and contact loads, impact and wear and used in mechanical engineering, aerospace, transport equipment, as well as for the production of workpieces with optimal electrical and thermal properties for heat power engineering and electrical engineering, the main of them are the optimal combination of mechanical properties-plasticity and strength, the required level of heat resistance, durability, fatigue strength, hardness, wear resistance, corrosion resistance, electrical resistance. Currently, to obtain bulk aluminium workpieces for various industries that meet the above requirements for physical and mechanical properties, three methods are mainly used: a) metallurgical methodsmethods of modifying the chemical composition of the material by alloying with various modifiers [1-3]; b) heating methods-methods of heat treatment and thermomechanical treatment [4,5]; c) methods of severe plastic deformation (SPD) [6][7][8][9][10]. The first two methods are considered traditional and have a number of problems and drawbacks: a) due to the use of often expensive alloying additives (for example, rare earth elements such as scandium, cerium, etc.…”
The article presents the results of stress state analysis for workpieces from aluminium alloy 6063 cold-formed in a closed die. Mathematical methods of computer modelling (finite element method) and slip lines (slip-line field method) are used for the analysis. The experimental procedure for repeated cold deformation in a closed matrix (in several passes and/or cycles), the mechanisms of grain grinding and material hardening under the influence of grain-dislocation factors are described. The results of the stress state study of the material during cold deformation (at room temperature) show that the volume of the workpiece is mainly compressive stresses, the values of which are in the range from −273 MPa to −533 MPa. As found, due to the hydrostatic stress from the side of the punches and the side walls of the semi-dies, the workpiece is subjected to triaxial compression, which makes it possible to obtain volumetric spherical workpieces with ultrafine-grained nanostructure in a closed die with minimal processing cycles.
“…1. The occurrence of superplasticity was reported not only after HPT processing of thin disc specimens [7,8], but also using the ring samples [9,10], bulk samples [11,12] as well as after continuous high-pressure torsion extrusion [13]. Different materials have been tested experimentally [14] and theoretically [15] through the application of HPT process such as aluminum alloys [8,16], nickel [17], copper [15], titanium alloys [3,18], polymers [19], zirconium [20,21], Magnesium alloys [22], aluminum-zinc alloys [23], intermetallics [24,25] and others (see [26,27]).…”
High Pressure Torsion (HPT) is a highly effective super-plastic deformation process for obtaining nano-materials with high performance mechanical properties. In view of its optimization, it is of paramount importance to evaluate the relations between the behavior of the material under the effects of different processing parameters. In this context, this work aims to highlight the plastic strain distribution in the deformed material as a function of the hydrostatic pressure, the torsion angle and the temperature of the material applied during the process. A typical amorphous polymer (Polymethyl-Methacrylate: PMMA) has been tested. Firstly, in order to identify the material parameters of a phenomenological elasto-viscoplastic model compression tests at different temperatures and strain rates have been carried out. Then, the distributions of the effective plastic strain, the equivalent plastic strain rate and the hydrostatic stress were analyzed using finite elements method. Recommendations on process conditions were
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