Papers by Keyword: Equal Channel Angular Pressing (ECAP)

Abstract: This research presents a numerical study on the Equal Channel Angular Pressing (ECAP) process using AA6061 aluminum alloy, employing Finite Element Analysis (FEA) with ABAQUS/Explicit software. The primary objective is to simulate the deformation behavior of AA6061 under different die angles (60°, 90°, and 120°) and evaluate the simulation results by comparing them to experimental findings. The study focuses on stress distribution, plastic strain, and deformation patterns during the ECAP process to identify the optimal processing conditions. The results provide insights into the effects of die angle on the material's deformation behavior and mechanical properties, offering a foundation for optimizing the ECAP process for AA6061.

Abstract: An attempt was made to synthesis Al-5083alloy through high energy ball milling and densification through ECAP. The elemental powders consisting of Al5083 was milled for 5, 10 and 15 hrs using Retsch high energy ball mill (PM400). The physical and structural properties of mechanically alloyed particulates were characterised by diffraction methods and electron microscopy. The 15hrs nanocrystalline structured particulates of Al5083 alloy shows crystallite size of 15nm. Scanning Electron Microscope (SEM) reveals the morphology of alloy which is irregular shaped. The size of alloyed particulates also measured using SEM and found to be 7μm for 15hrs of milling. The 15hr milled alloy particulates were densified by ECAP through 90^o die channel angle. Maximum densification of 92% and highest hardness of 63HRB was achieved for sample consolidated with route-A for two passes along with sintering.

Abstract: In this research, AZ31 and AZ91 magnesium alloys were used as hydrogen storage materials to compare the effects of equal channel angular pressing (ECAP) and high energy ball milling (HEBM) processes on the hydrogen storage properties. In addition, the effects of using different AZ magnesium alloys (AZ31 and AZ91) with the same processes and parameters on the hydrogen storage properties were investigated. The results show that the crystal size of AZ magnesium alloy has been decreased by both ECAP and HEBM processes. It was also revealed that AZ31 magnesium alloy processed by ECAP route B_C with 8 passes has faster absorption and desorption rate than AZ31 magnesium alloy processed by HEBM ball material ratio 30:1 with 300rpm. The capacity of two samples is 7.0 and 6.8 wt.%. The AZ91 magnesium alloy processed by HEBM ball material ratio 30:1 with 300rpm has faster hydrogen absorption and desorption rate than that of AZ91 magnesium alloy processed by ECAP route B_C with 8 passes at 375^oc. The capacity of two samples is both 6.7 wt.%.

Abstract: The evolution of microstructure of ZL205A alloy during equal channel angular pressing (ECAP) by route A at room temperature was investigated by OM, SEM and XRD, and the hardness of cast and heat treatment alloy from different strain were tested. The results showed that the grain of cast alloy were obviously refined, the massive q phase along the grain boundary were crushed, and prompts the distribution of q streamline after one pass through ECAP. After two passes of ECAP, the distribution of q phase is more uniform. After heat treatment through ECAP, the grains were also obviously refined, and elongated in axial direction, which also prompts the distribution of q streamline. The hardness was significantly improved after ECAP. The hardness of cast alloy increases from 65HV to 132HV after two passes, and that of heat treatment alloy increases from 112HV to 198HV. With the increase of extrusion passes, the number of dimples gradually increased and evenly distributed, the depth of dimples was of a similar level, and the distribution of precipitated phase is more uniform.

Abstract: Based on characteristics of direct extrusion for magnesium alloy seamless tube and continuous equal channel angular pressing (ECAP) of tubes, a new composite extrusion process of tubes including direct extrusion and many steps ECAP was invented firstly, which are shorten for TES process in this paper. A three-dimensional finite element thermo-mechanical coupled model and conditions for TES process were established. The extrusion process and cumulative strains evolution during TES process were simulated. The results show that TES process can improve the cumulative strains significantly. The microstructures observations of longitudinal sections for tubes fabricated by direct extrusion and TES process were carried out. It was found that when the extrusion temperature was 400°C, and extrusion ratio was 8.4 and the channel angle was 150°, TES process can refine the microstructures of tubes effectively.

Abstract: The ultrafine-grained copper was obtained by 12 passes of equal-channel angular pressing method. The uniaxial tensile tests at room temperature and the subambient temperature of 77 K show that the yield stress increases from the value of 128 MPa to the value of 138 MPa, respectively. In addition, the lowering the test temperature tends to the increase of the deformation before the failure. The fractographic analysis shows the transcrystalline ductile failure for all samples. Due to the high plasticity of nanostructured copper no influence of the nanoporosity on the failure process was observed.

Abstract: The Paper Deals with Microstructural and Mechanical Properties Changes during Severe Plastic Deformation Process in Beta Titanium Alloy Used for Hip Implants. Effect of Various Numbers of Passes through ECAP (Equal Chanel Angular Pressing) Die on Microstructure and Properties Have been Evaluated. Comparison between Virgin State Cast Alloy and Alloy after Several Steps of Severe Plastic Deformation Induced by ECAP Technology Have been Carried out. Mechanical Properties Have been Evaluated Using Miniaturized Specimens. from Experimental Work can Be Concluded Positive Effect of ECAP Technology both on Mechanical Properties (yield Stress as well as Tensile Strength) Including Grain Size.

Abstract: Mechanical properties and corrosion resistance of Mg alloys basically depend on their chemical composition. Both the mentioned can be influenced by mechanical or heat treatment. In this work was studied the effect of production technology and resulting microstructure on the corrosion resistance of AZ91 alloy. Corrosion resistance of the alloy (AZ91) was analyzed for material after casting and after treatment by ECAP. Result of ECAP treatment is fine grained microstructure of AZ91 alloy and uniform distributed of present intermetallic phases. Corrosion resistance of the experimental material was analyzed in 0.1 molar solution of NaCl through potentiodynamic tests. The ultra-fine grained microstructure after ECAP results in movement of thermodynamic curves to more positive values of corrosion potential (E_corr). From thermodynamic point of view, this means, that AZ91 alloy after ECAP has slightly higher corrosion resistance, as AZ91 alloy after casting; however the improvement of corrosion resistance is only minor due to the high reactivity of the magnesium in the corrosion environment.

Abstract: In this paper tensile properties at elevated temperature of extruded AZ91 magnesium alloy and the same alloy further processed by ECAP (exECAP) are compared. The tensile tests were performed at room temperature and for the temperature range of 100 to 300 °C. Loading speed 2 mm/min was used for the tests. At room temperature mechanical properties except elongation were slightly higher for extruded material yet still very similar to properties of exECAPed material. Overall trend of properties evolution with increasing temperature was also similar but the decrease of strength or the increase of elongation and reduction of area respectively is more intensive for exECAPed material. Elongation of exECAPed material exceeded elongation of extruded material more than twice at 300 °C and with value of ~260% this alloy exhibited pseudosuperplastic behavior.

Abstract: Pure molybdenum powder material was processed by equal channel angular pressing (ECAP) with different numbers of passes at the temperature of 400 °C and then Vickers microhardness measurements and scanning electron microscopy (SEM) analysis were conducted. The samples were further characterized with electron back scatter diffraction (EBSD) to examine the grain size. These experimental results exhibit that the powder material is well consolidated and the grains are refined by 2 passes of ECAP processing. In addition, discrete element method (DEM) was used to investigate the deformation behaviour of particles as well as the pores between the particles. The deformation of particles, the distribution of residual porosity and the variation of coordination number in pure molybdenum powder material sample during ECAP were obtained in microscopic scale and all the simulation results are well in line with the microstructure evolution.