The present research aimed to optimise process parameters such as outer corner angle (ψ = 0°-36°), frictional coefficient (μ = 0-0.05), inner corner angle (ω = 0°-8°) and die channel angle (φ = ...90°-120°) for the equal channel angular pressing (ECAP) die design considering a non-strain hardening material Al6061-T6 alloy using ABAQUS finite element analysis software in terms material flowability, corner gap formation, surface gap formation, induced strain intensity and strain distribution. The ECAP die having 100° φ, 24° ψ, 0.02 μ and 8° ω provide better material flowability, (no corner gap formation and surface gap formation), moderate induced strain intensity and homogeneous distribution. The ECAP processing on the designed die effectively modifies the microstructure morphology of as-cast Al6061 alloy. The α-Al grain size decreases and roundness increases and the thicker grain boundary is altered into the thinner boundary, as an effect of this, hardness and tensile strength improved by 28.3% and 32.7%, respectively.
In the present work, AZ91 alloy was successfully processed by equal channel angular pressing (ECAP) for up to 16 passes and rolling (R) for multiple passes with a total reduction of 75% in addition ...to a combination method with ECAP plus rolling (ECAP+R). The effects of various processes (ECAP, R and ECAP+R) on microstructure evolution were analyzed and the influence of ECAP process on the rolling performance was examined. The result shows that ECAP contributed to a homogenous grain structure and formed a texture with higher Schmidt factors that was easy for rolling. A plate with smoother surface and reduced edge cracks was observed in the ECAP+R process than in the single R process. Although the microstructure of the alloy was similar after ECAP+R and R process, the sample of ECAP+R was more refined and had stronger second phase precipitation than the sample of R, which resulted in better rolling characteristics, along with the external surfaces.
•Improvement of fatigue life of titanium by severe plastic deformation.•Description of localization of cyclic plasticity.•Different response of microstructure of Ti2 and Ti4 on severe plastic ...deformation.
The fatigue life and fatigue limit of commercially pure Ti grade 2 and 4 in coarse-grained and ultrafine-grained states were experimentally determined. Ultrafine structures were prepared by Conform severe plastic deformation method and by conventional Equal channel angular pressing, respectively. The differences in the improvement of fatigue life and the influence of both procedures on the fatigue limit based on 107 cycles to fracture are discussed in terms of grain refinement, microstructure, differences in fatigue damage mechanism and influence of surface roughness on the initiation of fatigue cracks. Improvement in fatigue life was observed for both materials, however, the improvement of the fatigue limit was found only for Ti grade 2.
Mg–Pb-9.2Al-0.8B alloy faces a significant strength-toughness balance problem in applications. To address this challenge, severe plastic deformation was applied to the alloy by combining traditional ...extrusion with multi-pass equal channel angular pressing (EX-ECAP). The research delves into the microstructural evolution (including broken β-Mg17Al12 and non-uniform Mg2Pb particles) and its effects on the strengthening mechanisms. The synergistic effects of grain boundary strengthening due to grain refinement, Orowan strengthening, geometrically necessary dislocation strengthening, and coefficient of thermal expansion strengthening collectively enhance the tensile strength and ductility, balancing the strength and toughness. The results showed an impressive ultimate tensile strength of 386.1 MPa, which is 2.33 times that of the as-cast alloy. The altered fracture morphology clearly indicated a transformation from brittle to brittle-ductile fracture mode. During the deformation process, the activation of dislocations, atomic-scale ripples, minor lattice distortions, and kink bands enhance the macroscopic flexibility. The introduction of EX-ECAP presents new opportunities for manufacturing high-performance Mg–Pb-9.2Al-0.8B alloy through integrated deformation techniques.
In this study, the ECAP process was conducted using two different dies of channel angles (Φ) 120° and 90° to extrude pure Cu for 2 and 6 passes of route Bc at room temperature. Optical Microscopy ...(OM) was used to study the microstructure of Cu before and after ECAP processing. Vicker’s microhardness was measured along the transvers section of the Cu billets. The electrical conductivity of the Cu billets was measured at room temperature and expressed as a relative percentage of the international annealed copper standard. 2-passes using the two dies revealed an elongated ultrafine-grained structure that aligned parallel to the extrusion direction. 6 passes using the 90°-die resulted in more ultrafine-grained equiaxed structure compared to the Cu billets processed through the 120°-die. Processing through 6-passes revealed a significant increase in the Cu Vicker’s microhardness by 56% and 72% through processing using the using the 120°-die and 90°-die, respectively when it put in comparison with the as-annealed samples. The electrical conductivity finding revealed that ECAP processing up to 6-passes resulted in insignificant decrease of 6.6% compared to the as-annealed counterpart which indicated that ECAP processing can strengthen the Cu billets without losing its electrical conductivity
An investigation was conducted to study the influence of equal-channel angular pressing (ECAP) and post-ECAP aging at 393 K for 20 h on the microstructures and tensile properties of a supersaturated ...Al-Zn-Mg alloy together with the effect of pre-ECAP heat treatments on the mechanical properties of the alloy after ECAP and after post-ECAP heat treatments. The results show that during ECAP processing for up to 4 passes for the supersaturated Al alloy there is a simultaneous occurrence of grain refinement, increases in the dislocation density and dynamic aging precipitation forming large numbers of fine spherical well-distributed precipitates which enhance the yield strength but decrease the ductility. During post-ECAP aging, there is a limited dislocation recovery with slight grain growth and the precipitate sizes increase together with the formation of a few larger platelet precipitates and the transformation of G.P. zones to η′ and η′ to η leading to a strength reduction after 4 passes of ECAP. The precipitates in the ECAP-processed alloy with pre-ECAP in the supersaturated state formed through dynamic aging precipitation are higher in their volume fraction, smaller in their size and more homogeneously distributed in the Al matrix than those in the alloy with pre-ECAP in the peak aging state which mainly come from the fragmented η′ existing in the matrix before ECAP. The strengths of the alloy both after ECAP processing and after post-ECAP heat treatments with pre-ECAP in the supersaturation state are higher than with pre-ECAP in the peak aging state.
•ECAP processing enhances yield strength of supersaturated Al-Zn-Mg.•Post-ECAP aging decreases strength for the supersaturated alloy after 4 passes.•During ECAP processing dynamic aging precipitation occurs.•Pre-ECAP heat treatments affect the strength of the alloy after ECAP processing.•Pre-ECAP heat treatments also affect the strength after post-ECAP heat treatments.
The traditional method of recording electrically evoked compound action potentials (ECAPs), as implemented in the MAESTRO clinical software (standard ART), requires manual adjustments during ...threshold determination through a specialist. The "FineGrain" research tool (FineGrain RT) uses a continuous stimulation paradigm combined with automatic ECAP threshold determination. The aim of this study was to compare the FineGrain RT with standard ART.
ECAPs were recorded with standard ART and the FineGrain RT in paediatric cochlear implant recipients. Different stimulation rates were used for FineGrain ECAP recordings (40, 60, and 76 Hz).
Thirteen children (6 − 19 years) participated in this study - nine were bilaterally and four unilaterally implanted, resulting in a total of twenty-two implanted ears.
ECAP threshold determination success rates were similar between the two approaches (92% and 89%) and ECAP thresholds correlated well (r: 0.94, p < 2.2e
-16
) with average ART thresholds being lower than FineGrain RT thresholds. FineGrain stimulation with different stimulation rates did not have a significant effect on ECAP thresholds but ECAP thresholds at medial and apical contacts were lower compared to basal contacts.
TheFineGrain research approach is a reliable replacement for standard ART in clinical practice.
Equal Channel Angular Pressing (ECAP) is a promising severe plastic deformation technique that has gained significant attention for its ability to refine grain structure and enhance mechanical ...properties in metallic materials. This study focuses on investigating the impact of ECAP with route A and up to three passes on the mechanical properties and microstructure of 1050 aluminum. The study yielded compelling evidence of substantial enhancements in yield strength, ultimate tensile strength, and hardness. Specifically, these properties increased from 58.19 MPa, 67.06 MPa, and 23.85 HV in the annealed state to 133.02 MPa,141.21 MPa, and 38.96 HV after the third pass of the ECAP process, respectively. Furthermore, an interesting observation was made regarding the hardness ratio, which demonstrated a noticeable decrease with an increasing number of ECAP passes. This phenomenon correlated with a reduction in the size of dimples on the fracture surface. Microstructural analysis via scanning electron microscopy SEM confirms a significant reduction in grain size after ECAP passes, indicating the effectiveness of the process in inducing microstructural refinement. These findings collectively underscore the potential of ECAP with route A in enhancing the mechanical properties and microstructure of 1050 aluminum. This research contributes valuable insights into the application of ECAP with route A as a viable strategy for improving the performance of aluminum alloys.
In this work, the consolidation of blended elemental powders of iron, manganese and aluminum (Fe-25Mn-15Al wt.%) was performed by Equal Channel Angular Pressing (ECAP). Samples were consolidated at ...room temperature in a Φ = 120° die by a single pass and a second pass in route A. Both samples were heat treated at 650 °C and water cooled. Prior to heat treatment, samples presented a dense but chemically inhomogeneous structure. Fe and Al particles were highly deformed, whereas, Mn was almost undeformed. Mn particles were partially shattered by friction with Fe and Al particles. After heat treatment, the samples were characterized by SEM-EDX and presented substantial interdiffusion along the particles interfaces. It is believed that higher deformations by ECAP may improve the sinterability of consolidated samples in order to densify and chemically homogenize it.
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