Equal Channel Angular Pressing Research Articles

Ductility enhancement in Mg–8.7Gd–4.18Y–0.42Zr magnesium alloy fabricated through extrusion and equal channel angular pressing (EX-ECAP)

Ductility enhancement in Mg–8.7Gd–4.18Y–0.42Zr magnesium alloy fabricated through extrusion and equal channel angular pressing (EX-ECAP)

Regulating hardness homogeneity and corrosion resistance of Al-Zn-Mg-Cu alloy via ECAP combined with inter-pass aging

The novel processing strategies of Equal Channel Angular Pressing (ECAP) combined with inter-pass aging was designed, and XRD, SEM, TEM, electrochemical testing, and hardness testing were used to evaluate the relationship between microstructure and performance of alloys in this work. The results indicate that the hardness uniformity of the circular cross-section perpendicular to the extrusion direction was improved by combining ECAP with inter-pass aging, resulting in a hardness inhomogeneity factor (∼0.030) that was lower than that achieved by peak aging and double-stage aging alloys. Polarization curves and electrochemical impedance spectra show that a more negative corrosion potential and a smaller corrosion current density were possessed by the alloy, with the maximum intergranular corrosion depth (IGC) being reduced to 38 μm. Microstructure observation indicates that the improvement in hardness uniformity is due to the uniformity of grain size and the improved distribution and size of the η’ phase, which is attributed to the interaction between the pinning and shear effects of precipitates and dislocations during deformation. The enhanced corrosion resistance was attributed to an orderly combination of deformation and aging that increases the grain boundary volume and disrupts the η phase continuity within grain boundaries.

The microstructure evolution and mechanical properties of Ti–1300 alloy during ECAP deformation and subsequent aging treatment

The effect of Equal channel angular pressing (ECAP) deformation on the microstructure, mechanical properties, and aging behavior of solution treated Ti–1300 alloy was investigated. The results show that the grains are not broken during ECAP deformation due to coordination of grain rotation. The dominant deformation mechanism involved dislocation slip and twinning. The ECAP deformation has a significant effect on the subsequent aging behavior. The microstructure of aged samples comprised αs phase in β matrix. The precipitation of αs phase in the pre-deformed sample is higher than that in the solution treated sample, which is reflected in the improvement of microhardness of the pre-deformed + aging sample. The microhardness of the alloy after ECAP deformation increases with decreasing aging temperature and increasing aging time.

Influence of Cu Alloying on the Microstructure and Properties of the Al–Fe Alloy, Produced by Electromagnetic Casting and Subjected to Equal-Channel Angular Pressing

Influence of Cu Alloying on the Microstructure and Properties of the Al–Fe Alloy, Produced by Electromagnetic Casting and Subjected to Equal-Channel Angular Pressing

Influence of Equal Channel Angular Pressing and Cyclic Extrusion Compression on the Microstructure Evolution and Mechanical Properties of Pure Aluminum.

The influence of equal channel angular pressing (ECAP) and cyclic extrusion compression (CEC) of Al-1080 on the pressing load, microstructure, and tensile properties was investigated. The pressing peak loads of the CEC were 218.8-265.4% higher than those of the ECAP, with a more complex load behavior in the CEC process. The deformation morphology of the ECAP samples indicates an improvement in the deformation homogeneity with the number of passes. Shear band morphology with a decrease in the shear band width from the center to the outer surface makes up the predominant pattern of the CEC samples. The ECAP samples have 13.9-44% smaller average grain sizes, with 3.8-8.1% higher high-angle grain boundaries (HAGBs) than the CECed samples. The ECAP and CEC processing improve the tensile strength. However, the ECAP sample's tensile strength (UTS) and the proof strength (σ0.2) were 11.5-20.6 and 2.6-16.4% higher than that of CEC, without noticeable differences in elongation. The σ0.2 values were predicted accurately with a deviation range of 1.8-7.3% from the experimental one. The ECAP samples are easy to process under lower loads. Moreover, ECAP samples have an equiaxed grain microstructure with a higher degree of deformation homogeneity and tensile strength.

An in vitro and in vivo study of biodegradable Zn–Cu–Li alloy with high strength and ductility fabricated by hot extrusion combined with room-temperature ECAP

Deformation processing is a commonly used strategy to improve the microstructure and hence mechanical properties of biodegradable Zn alloys. However, a single conventional processing method is usually limited in achieving this goal. In this work, hot extrusion combined with room-temperature equal channel angular pressing (ECAP) was used to fabricate biodegradable Zn–Cu–Li alloy. Compared to the hot-extruded alloy, the further ECAPed alloys have significantly finer Zn grains and precipitate more submicron- and nano-sized ε-CuZn4 particles. Moreover, the 4-pass as-ECAPed alloy exhibits the best comprehensive mechanical properties with yield strength of 315 ± 3 MPa, ultimate tensile strength of 444 ± 13 MPa and elongation of 81 ± 5%, which are 13.3%, 38.8% and 72.3% higher than those of the hot-extruded alloy, respectively. In addition, in vitro and in vivo tests were performed on the 4-pass as-ECAPed alloy to evaluate its corrosion behavior, antibacterial property, cytotoxicity and biocompatibility. In vitro results showed that the 4-pass as-ECAPed alloy exhibits better corrosion resistance than the 8-pass alloy. Also, it shows good antibacterial property, hemocompatibility and cytocompatibility. In vivo results demonstrated that the 4-pass as-ECAPed alloy exhibits faster and more uniform degradation than the pure Zn (as a control group). Both the pure Zn and 4-pass as-ECAPed alloy promote formation of new bone, the mass of which increases over time. The 4-pass as-ECAPed alloy shows slightly weaker osteogenic capacity but better overall osteointegration than the pure Zn. Furthermore, both the pure Zn and 4-pass as-ECAPed alloy exhibit good in vivo biosafety.

Developing high elongation of Ca-containing Zn alloys with superior osteogenic and antibacterial properties

The development of high-strength zinc (Zn) alloys significantly contributes to the field of orthopedics by enhancing their osteogenic properties. Calcium (Ca) is pivotal for bone composition; however, its incorporation into the Zn matrix often hampers elongation due to the formation of large-sized CaZn13 phases. In this study, two Zn alloys with different Ca contents were prepared, and their microstructures, mechanical properties, corrosion behavior and biocompatibility were investigated. Results indicate that the Zn alloy with high Ca content exhibits large-sized and high-volume-fraction CaZn13 phases, which do not significantly change during equal channel angular pressing (ECAP). The grain sizes of ECAPed Zn alloys decreased from 36.75 μm and 35.81 μm of as-cast state to 4.32 μm and 1.71 μm, respectively. Refined microstructures contributed to the improvement of mechanical properties of Zn alloys, which have elongation over 15 % higher than that of all Zn-Mg-Ca alloys reported so far. The high elongation of Zn alloys originates from the inhibition of the propagation of microcracks which generated from the Zn/CaZn13 interphase. Moreover, the formation of large-sized CaZn13 phases leads to the severe local corrosion through enhancing galvanic effect, finally increasing corrosion rate. During degradation, the release of metallic ions, such as Zn2+, Mg2+, and Ca2+, are beneficial to the cell viability and osteogenic properties. And the accelerated release of Zn2+ plays a role in antibacterial performance. These results are very helpful for promoting the application of biodegradable Zn alloys in the field of orthopedics.

Investigating the combined influence of rolling, ECAP processes, and intermediate annealing on mechanical and microstructural properties of beryllium copper alloy 25

A beryllium copper alloy 25 underwent a series of processing steps involving rolling, equal-channel angular pressing (ECAP), and subsequent annealing. This study delved into the combined effects of these processes on the microstructural evolution and mechanical properties of the deformed beryllium copper alloy 25. The investigation utilized optical microscopy, scanning electron microscopy, transmission electron microscopy, room temperature Vickers hardness testing, and tensile testing. The findings reveal a notable enhancement in the strength of the beryllium copper alloy 25 while preserving its ductility after subjecting it to six ECAP passes followed by annealing at 210 °C for 20 min, applied to the rolled sample. Initially, an increase in number of ECAP passes resulted in a gradual reduction in grain size and a weakening of the alloy's texture. This led to an increase in ultimate tensile strength up to 333.5% without reducing in percentage elongation. Notably, after six ECAP passes, the average grain size decreased from 48 µm to less than 1 µm, yielding exceptional comprehensive mechanical properties with significantly improved strength and plasticity. The resultant material exhibits promising potential for fabrication into bars and plates for a wide range of applications in aerospace and marine industries.

Effect of equal channel angular pressing on microstructure and mechanical properties of a Cu-Cr-Ni-Si-Co alloy

The microstructural and properties of a Cu-Cr-Ni-Co-Si alloy produced by equal channel angular pressing (ECAP) were systematically investigated. After the fourth-pass ECAP deformation, the average grain size was refined from 30 μm (solid solution state) to below 3 μm, resulting in a fine and regularly shaped equiaxed crystalline microstructure. The distribution of grain boundaries became more uniform. During ECAP deformation, the volume fraction of Copper texture {001} <100> decreased, while that of the Brass {011} <211> increased, and the Shear {123} <634> remained nearly constant. An increase in the number of ECAP deformation passes facilitated dynamic recrystallization, leading to an increase in the fraction of the recrystallized texture. After thermomechanical treatment (first-pass ECAP +450 °C aged/120 min + 80 % cold-deformation +450 °C aged/30 min), the alloy exhibited good mechanical properties, with a tensile strength of 546 MPa, a yield strength of 475 MPa, an elongation of 18.2 %, and an electrical conductivity of 52.8 %IACS. The main strengthening mechanisms included precipitation strengthening, dislocation strengthening and grain boundary strengthening, with the precipitation strengthening accounting for 45.6 % of the yield strength.

Effect of short-time high-temperature stabilization on the microstructure and tensile property of severely deformed Al-Mg-Sc alloy

In this paper, the effect of short-time high-temperature stabilization on the microstructure and tensile property of the Al-Mg-Sc alloy deformed by equal channel angular pressing (ECAP) has been investigated. The results show that the 2-pass ECAP cannot completely refine the grain, and the distribution of the deformed structure is inhomogeneous. After short-time stabilization, the grain of the material is refined, the shear zone becomes small grains with a size of about 1 μm, and the non-uniform deformation structure is alleviated. This change results in a small reduction in strength but a large increase in toughness. Short-time stabilization also improves the workability of the material. Re-deforming the material by another 2 pass ECAP, the sample with short-time stabilization demonstrates fewer internal defects, a more uniform structure, and finer grains.

Microstructure evolution of pure magnesium based on dynamic recrystallization during ambient equal channel angular pressing

An as-extruded pure Mg bar was subjected to ambient equal channel angular pressing (ECAP) up to four passes. Recrystallization behavior of as-ECAPed samples was investigated by scanning electron microscope-electron back-scatter diffraction (SEM-EBSD). After four-pass ECAP, grain orientation was significantly changed and basal-oriented texture was formed with c-axes of most grains nearly parallel to transverse direction (TD). Dynamic recrystallization (DRX) shows obvious orientation dependence during ambient ECAP, with continuous dynamic recrystallization (CDRX) partly transforming into discontinuous dynamic recrystallization (DDRX) after the four-pass ECAP.

Simulation of the Process of Temperature Field Changing of a Zr–1%Nb Zirconium Alloy Billet During Equal-Channel Angular Pressing

Using mathematical modeling in the QFORM software package, the data on the temperature distribution of a billet made of a zirconium alloy E110 (Zr–1%Nb) in its longitudinal and transverse sections during an equal-channel angular pressing (ECAP) were obtained. The initial data on the geometric parameters of the billet and the die of the ECAP unit are presented, and the conditions for carrying out the process of severe plastic deformation, as well as the chemical composition and physical characteristics of the Zr–1%Nb alloy necessary for carrying out the computational modeling are described. The values of the billet temperature were determined for the calculated moments of the passage of the billet through the junction of the die channels, which corresponded to 25%, 50%, and 75% of its length. It is shown that during the ECAP process at a given pressing speed, in the section corresponding to the junction of the matrix channels, an increase in the billet temperature relative to its initial heating occurred by an amount of about 10 ºC.

Mitigating adverse effects of Cu-containing intrauterine devices using a highly biocompatible Cu[sbnd]5Fe alloy

Copper-containing intrauterine devices (Cu-IUD) are adopted by worldwide women for contraception with the advantages of long-term effectiveness, reversibility and affordability. However, adverse effects occur in the initial implantation stage of Cu-IUD in uterine because of the burst release of Cu2+. To minimize the burst release, in this study, we designed a series of Cu–Fe alloys with 0.5 wt%, 1 wt% and 5 wt% Fe and also further produced ultrafine grained (UFG) structure for these alloys via equal-channel angular pressing. The microstructures and properties of the coarse grained (CG) Cu, CG Cu–Fe alloys and UFG Cu–Fe alloys were systematically investigated, including grain structure and phase compositions, metallic ions release behavior, electrochemical corrosion performance, and in vitro cytotoxicity. With careful comparison and selection, we chose the CG Cu–5Fe and UFG Cu–5Fe for in vivo tests using rat model, including tissue biocompatibility, in vivo corrosion behavior, and contraceptive effectiveness. Moreover, the corrosion mechanism of the Cu–5Fe alloy and its improved biocompatibility was discussed. Both CG and UFG Cu–5Fe alloys exhibited dramatic suppression of Cu2+ release in simulated uterine fluid for the long-term immersion process. The in vivo tissue compatibility was significantly improved with both CG and UFG Cu–5Fe alloys implanted in the rats’ uterine while the high contraceptive efficacy was well maintained. Due to the superior biocompatibility, the CG and UFG Cu–5Fe alloys can be the promising candidate material for Cu-IUD. Statement of significanceA highly biocompatible Cu–Fe alloy was designed and fabricated for Cu-containing intrauterine devices (Cu-IUD). With 5 wt% Fe, the burst release of Cu2+ is inhibited due to the formed galvanic cell of Cu and Fe, resulting in earlier release of Fe3+. As Fe is the most abundant essential trace element of human body, it can mitigate the toxic effects of Cu2+, thus significantly improving both in vitro cell compatibility and in vivo tissue compatibility. More importantly, the Cu–5Fe alloy exhibits 100 % contraceptive efficiency as the CG Cu, but with greatly reduced adverse effects to the uterus tissues. An advanced Cu-IUD can be developed using Cu–Fe alloys.

Investigating the Influence of Thermomechanical Equal Channel Angular Pressing (ECAP) Improved Die on AA-6061

Investigating the Influence of Thermomechanical Equal Channel Angular Pressing (ECAP) Improved Die on AA-6061

Enhanced Strengthening and Toughening of T6-Treated 7046 Aluminum Alloy through Severe Plastic Deformation

The 7046 aluminum alloy possesses a favorable fatigue property, corrosion resistance and weldability, but its moderate strength and plasticity limit its wider application and development. In the present study, severe plastic deformation (SPD) was applied prior to T6 treatment to significantly enhance the strength and toughness of the 7046 aluminum alloy. The results show that the alloy processed by four passes of equal channel angular pressing (ECAP) at 300 °C prior to T6 treatment exhibits an excellent mechanical performance, achieving an ultimate tensile strength (UTS) and elongation (EL) of 485 MPa and 19%, respectively, which are 18.6% and 375% higher than that of the T6 alloy. The mechanical properties of the alloy are further improved by an additional room temperature (RT) rolling process, resulting in a UTS of 508 MPa and EL of 23.4%, respectively. The increased presence of η′ and Al6Mn phases in the 300°C4P-R80%-T6 and 300°C4P-T6 alloys contributes to a strengthening and toughening enhancement in the SPD-processed T6 alloy. The findings from this work may shed new insights into enhancing the 7046 aluminum alloy.

Evaluation of microstructure and mechanical properties of Al1050/Al2O3/Gr composite processed by forming operation ECAP

Abstract Enhancement of microstructure and mechanical features of the hybrid aluminum matrix composite (HAMC) prepared by the stir-casting process (SCP) is quite significant for failure prevention during the service. In this work, the circular rod of hybrid aluminum matrix composite reinforced with particles of alumina (Al2O3) 50 μm, and graphite (Gr) 40–100 µm fabricated by SCP was adopted. This Al1050/Al2O3/Gr composite was subjected to severe plastic deformation using equal channel angular pressing (ECAP) at room temperature to show the impact of this process on the microstructure and mechanical features of the fabricated composite. Grain refinement, strength, and hardness were evaluated at different forming passes (1P, 3P, and 5P) with two channel angles (die angles) of 120° and 135°. The results revealed that the number of ECAP cycles has a significant effect on the refinement of the grain size. The fifth pass of ECAP (5P ECAP) with a die angle of 120° gave more refinement of the grains in the range of 36–75 nm compared to other passes. On the other hand, the strength and hardness relatively augment until 5P ECAP with increasing the cycle number at two die angles of 120° and 135°. The ultrafine grain can reduce the voids of the aluminum matrix then the hardness is enhanced.

A new severe plastic deformation technique of combined extrusion and torsion to prepare bulk ultrafine grained copper

Reducing grain size is a well-established method for strengthening metals. In this study, a novel severe plastic deformation technique—combined extrusion and torsion (CET) with composite strain—was developed to fabricate bulk ultrafine grained metals. A single pass of CET treatment (with a rotation velocity of 1 r/s and extrusion speed of 3 mm/s) refined coarse-grained copper from 54 μm to 450 nm at room temperature, resulting a significant increase in hardness from 0.55 GPa to 1.3 GPa. The CET technique addresses the limitations of conventional extrusion-processed copper (without torsion), which suffers from gradient microstructure and hardness distribution. It provides enhanced strain accumulation under the same extrusion ratio conditions. The more homogeneous microstructures and properties of CET-processed copper rods are attributed to the reduced strain gradient due to torsion. Additionally, targeted finite element analysis indicated that the CET technology requires 37 % less extrusion load and offers at least 30 % more strain compared to conventional extrusion methods. Compared with other severe plastic deformation methods, such as equal channel angular pressing and high-pressure torsion, which involve simpler deformation processes, the CET technique shows considerable promise for large-scale manufacturing of ultrafine-grained metals.

Enhancing Mechanical Properties of Cast Ingot Al6061 Alloy Using ECAP Process

AbstractGrain refinement and mechanical property enhancement of cast ingot aluminum 6061 alloy were achieved using equal-channel angular pressing (ECAP) at room temperature, employing route A and route R types. Analytical, finite element and experimental methods were utilized to investigate the alloy’s deformation behavior under the ECAP process. The tensile tests conducted at room temperature demonstrated a significant increase in strength with an increasing number of pressings, reaching 44.23, 53.19, and 56.7% for 1-pass, route A, and route R types 2-passes of the ECAP process, respectively. However, ductility, as indicated by elongation, gradually decreased after the first pressing. Electron backscatter diffraction was employed to reveal submicrometer grain sizes resulting from the ECAP process. The grain structure showed substantial improvement under route A and route R types at a 2-passes ECAP process. Wear tests conducted under loads of 10 and 25 N showed an increase in the coefficient of friction within the minimum wear loss intervals. Rockwell hardness also exhibited a significant increase of 119.3, 176.3, and 164.8% at 1-pass and 2-passes using routes R and A, respectively. As part of the evaluation, analytical models were computed using Python, and finite element simulations were performed using ABAQUS software. The results from analytical and finite element simulations demonstrated good agreement with the experimental data.

Conjoint influence of equal channel angular pressing and annealing on microstructure and mechanical properties of aluminum alloy 7075

AbstractThe effect of equal channel angular pressing combined with inter‐pass and post‐process annealing on the microstructure and mechanical properties of the Al‐7075 alloy has been studied. The samples underwent successful equal channel angular pressing for three passes using the Bc route. The most significant changes in mechanical properties were observed after the first pass. Despite an 88 % reduction in grain size, the hardness of the alloy increased by 45 % and the fracture toughness decreased by 75 %. Post‐process annealing was found to be an effective method for enhancing the alloy‘s toughness. Annealing the one‐pass sample at 310 °C resulted in a 33 % increase in fracture toughness; from 15.8 J to 21.02 J. Inter‐pass annealing had a lesser impact on improving fracture toughness compared to post‐process annealing. It can be concluded that a balanced combination of strength and toughness can be achieved by utilizing a combination of equal channel angular pressing and inter‐pass or post‐process annealing. Examination of the fracture surfaces of the samples revealed intragranular fractures, with the annealed samples exhibiting higher energy absorption during impact and better toughness compared to the non‐annealed sample.

Tailoring Deformation Homogeneity of WE43 Alloy through Strain Rate Sensitivity and Back Pressure during Equal Channel Angular Pressing

AbstractEqual channel angular pressing (ECAP) of the magnesium alloys at room temperature owing to their limited workability is challenging. Successful ECAP processing of WE43 magnesium faces two main difficulties, heterogeneous distribution of the strain rate and also tensile strain accommodation on the top surface of the workpiece, leading to catastrophic segmentation of the alloy. In this paper, strain rate sensitivity (SRS) was studied to adopt a proper preprocessing of the material before ECAP processing. The SRS exponents, obtained from compression tests, revealed that solution treatment reduced the SRS of the alloy. To mitigate strain accommodation, an ECAP core-sheath configuration was used to induce back pressure for the sake of deformation homogeneity improvement. A combination of experimental processing and 3D finite element method simulations was applied to the solution-treated WE43 alloy with different core sizes and sheath materials. By finding the optimized core sizes and sheath materials with higher strengths, the differences in microhardness and equivalent plastic strain were reduced. Besides, the adequate magnitude of back pressure and the imposed fully compressive stress prevent fragmentation of the WE43 core during ECAP. After stepwise modifications, the plastic strain inhomogeneity index decreased from 1.340 to 0.671.