scholarly journals Increase in the Mechanical Strength of Mg-8Gd-3Y-1Zn Alloy Containing Long-Period Stacking Ordered Phases Using Equal Channel Angular Pressing Processing

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 221 ◽  
Author(s):  
Gerardo Garces ◽  
Pablo Pérez ◽  
Rafael Barea ◽  
Judit Medina ◽  
Andreas Stark ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Yield Stress ◽  
Equal Channel Angular Pressing ◽  
Volume Fraction ◽  
Extrusion Direction ◽  
Grain Structure ◽  
Long Period ◽  
Angular Pressing ◽  
Β Phase ◽  
Ordered Phases

The evolution of the microstructure and mechanical properties during equal channel angular pressing processing has been studied in an extruded Mg-Gd-Y-Zn alloy containing long-period stacking ordered phases. After extrusion, the microstructure is characterized by the presence of long-period stacking ordered fibers elongated along the extrusion direction within the magnesium matrix. The grain structure is a mixture of randomly oriented dynamic recrystallized and coarse highly oriented non-dynamic recrystallized grains. Rare-earth atoms are in solid solution after extrusion at 400 °C and precipitation takes place during the thermal treatment at 200 °C. Precipitation of β’ prismatic plates and lamellar γ’ in the basal plane increases the tensile yield stress from 325 to 409 MPa. During equal channel angular pressing processing at 300 °C, the volume fraction of dynamic recrystallized grains continuously increases with the strain introduced during the equal channel angular pressing process. Precipitation of β phase is equally observed at grain boundaries of the ECAPed alloy. Dynamic recrystallized grain size decreases from 1.8 µm in the extruded material to 0.5 µm in the ECAPed alloy. Thermal treatment at 200 °C of ECAPed materials results in an increase of the yield stress up to 456 MPa, which is maintained up to 200 °C.

Effect of Deformation Route on the Mechanical Properties of CP-Ti Deformed by Equal Channel Angular Pressing (ECAP)

2007 ◽  
Vol 345-346 ◽  
pp. 125-128 ◽  
Author(s):  
S.H. Chon ◽  
S.M. Liu ◽  
T.N. Kim ◽  
Joong Kuen Park
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Equal Channel Angular Pressing ◽  
Uniform Elongation ◽  
Grain Structure ◽  
High Yield ◽  
Prismatic Slip ◽  
Angular Pressing ◽  
High Yield Stress ◽  
Cp Ti

The effect of deformation route on the mechanical properties of grade-1 CP-Ti deformed by equal-channel angular pressing (ECAP) was studied using tensile testing, TEM observation, Xray pole figure measurement, and ODF calculation. Route Bc showed high yield stress and comparatively large uniform elongation, thus high ultimate tensile strength, because of its fine grain structure with high angle grain boundary. The reason for this was because of the occurrence of prismatic slip in route Bc, in addition to the commonly occurring basal slip. Route C showed surprisingly high yield stress despite of its unfavorable grain structure because of the significant contribution of texture hardening.

Study of Sintering of Iron Powder Bars Processed by Equal Channel Angular Pressing

2014 ◽  
Vol 802 ◽  
pp. 404-408 ◽  
Author(s):  
Mônica Paula Ribeiro ◽  
Marcio Ferreira Hupalo ◽  
Selauco Vurobi ◽  
Osvaldo Mitsuyuki Cintho
Keyword(s):  
Iron Powder ◽  
Equal Channel Angular Pressing ◽  
Volume Fraction ◽  
Substantial Reduction ◽  
Microstructural Characterization ◽  
Porosity Evolution ◽  
Angular Pressing ◽  
Internal Angle ◽  
Quantitative Stereology ◽  
1045 Steel

The main aim of this work is to show porosity evolution during application of various processing conditions to a high-purity (99.7 wt.%) iron powder, including compacting, sintering and equal channel angular pressing (ECAP). Iron powder bars with dimensions of 8x8x30 mm and 8x8x10 mm were axially pressed with pressures ranging from 100MPa to 250MPa, followed by sintering at 1100oC during 30 minutes under argon atmosphere. Sintered bars were processed by ECAP at room temperature in a single pass, using a SAE 1045 steel die with an internal angle of 120o. Microstructural characterization was performed by light optical microscopy (LOM) and quantitative stereology. ECAP processing resulted in a substantial reduction in the porosity levels for specimens pressed at 100 MPa and 150 MPa. The sample compacted with 150MPa and processed by ECAP with back-pressure showed the lowest volume fraction of porosity. Higher compacting pressures caused an increase in porosity levels. This result is explained by presence of cracks prior to ECAP and the concurrent action of severe stress-strain states during extrusion.

Tensile Deformation Characteristics of Commercial Mg Alloys Processed by Equal Channel Angular Pressing

2004 ◽  
Vol 449-452 ◽  
pp. 645-648
Author(s):  
Si Young Chang ◽  
Sang Woong Lee ◽  
Jin Chun Kim ◽  
Young Seok Kim ◽  
Dong Hyuk Shin
Keyword(s):  
Tensile Strength ◽  
Yield Stress ◽  
Equal Channel Angular Pressing ◽  
Tensile Deformation ◽  
Az31 Alloy ◽  
Mg Alloys ◽  
Deformation Characteristics ◽  
Angular Pressing ◽  
Fe Alloys ◽  
Hot Rolled

The commercial AZ31 and AZ61 Mg alloys were subjected to equal channel angular pressing (ECAP) after hot rolling at 673 K. The hot-rolled AZ31 alloy could be ECA pressed at 493 K. The 4 ECA pressed AZ31 alloy revealed the microstructure of dynamically recrystallized grains with a grain size in range of 1 to 10μm. Despite the dynamic recrystallization during ECAP at higher temperatures ( > 1/2 Tm), the yield stress and tensile strength of AZ31 and AZ61 alloys drastically increased after 1 pressing. The yield stress gradually decreased with increasing the number of pressings, which contrasts with the behavior of the ECA pressed Al and Fe alloys, while the tensile strength increased slightly. In particular, the alloys showed nearly 3 times higher elongation than as-annealed one after 4 ECAPs, without sacrificing the tensile strength. These tensile deformation characteristics were explained based on the observation of the deformed microstructure in the vicinit of fracture surface.

scholarly journals Microstructure and Properties of Mg-Zn-Y Alloy Powder Compacted by Equal Channel Angular Pressing

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1678 ◽  
Author(s):  
Chun Chiu ◽  
Hong-Min Huang
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Equal Channel Angular Pressing ◽  
Volume Fraction ◽  
Cast Alloy ◽  
Milled Powder ◽  
Microstructural Characterization ◽  
Compressive Yield Strength ◽  
Lpso Phase ◽  
Angular Pressing

Mg97Zn1Y2 (at %) alloy with a long period stacking ordered (LPSO) phase has attracted a great deal of attention due to its excellent mechanical properties. It has been reported that this alloy could be fabricated by warm extrusion of rapid solidified alloy powders. In this study, an alternative route combining mechanical milling and equal channel angular pressing (ECAP) was selected to produce the bulk Mg97Zn1Y2 alloy. Microstructural characterization, mechanical properties and corrosion behavior of the ECAP-compacted alloys were studied. The as-cast alloy contained α-Mg and LPSO-Mg12Zn1Y1 phase. In the as-milled powder, the LPSO phase decomposed and formed Mg24Y5 phase. The ECAP-compacted alloy had identical phases to those of the as-milled sample. The compacted alloy exhibited a hardness of 120 HV and a compressive yield strength of 308 MPa, which were higher than those of the as-cast counterpart. The compacted alloy had better corrosion resistance, which was attributed to the reduced volume fraction of the secondary phase resulting in lower microgalvanic corrosion in the compacted alloy. The increase in Y content in the α-Mg matrix also contributed to the improvement of corrosion resistance.

Microstructure and Texture Characterstics of a Near-Alpha Titanium Alloy Tube

2013 ◽  
Vol 683 ◽  
pp. 234-237 ◽  
Author(s):  
Yu Ting Zuo ◽  
Shu Feng Liu ◽  
Zhi Hui Zhang ◽  
Hui Na Ma ◽  
Wen Xia ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Volume Fraction ◽  
Extrusion Direction ◽  
Annealing Treatment ◽  
Fiber Texture ◽  
Electron Backscattered Diffraction ◽  
Texture Characteristic ◽  
Β Phase ◽  
Alpha Titanium ◽  
Titanium Alloy Tube

A near-alpha type titanium alloy Ti-4Al-1.5Mn tube was analyzed after extrusion deformation and annealing treatment. Electron backscattered diffraction is employed to explore the Microstructure and texture characteristic of the recrystallization alloy. The alloy is consisted of equiaxed α grains and fine β phase with {1 0-1 2} twins .It was found that the (10-10) fiber texture along the extrusion direction was the dominate texture in this alloy and the volume fraction was 40.7%.

scholarly journals Mechanical Properties and Microstructure Evolution of Mg-6 wt % Zn Alloy during Equal-Channel Angular Pressing

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 841 ◽  
Author(s):  
Jingli Yan ◽  
Zijun Qin ◽  
Kai Yan
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Testing Machine ◽  
Grain Structure ◽  
X Ray Diffraction ◽  
Angular Pressing ◽  
Transmission Electron ◽  
Zn Alloy

Equal-channel angular pressing (ECAP) was performed on a Mg (6 wt %) Zn alloy at temperatures from 160 to 240 °C and the microstructures and mechanical properties were studied using optical microscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and an electronic universal testing machine. The results showed that ECAP was effective for grain refinement and a bi-modal grain structure formed at low temperatures, which was stable during ECAP from 160 to 200 °C. MgZn2 phase and Mg4Zn7 phase were generated during the ECAP process. The mechanical properties remarkably increased after two repetitions of ECAP. However, the strengths could not be further improved by increasing the plastic deformation, but decreased when ECAP was performed between 200 and 240 °C. The mechanical properties of the ECAP Mg-6Zn alloy was determined by a combination of grain refinement strengthening, precipitation hardening, and texture softening.

scholarly journals The Effect of Equal-Channel Angular Pressing on Microstructure, Mechanical Properties, and Biodegradation Behavior of Magnesium Alloyed with Silver and Gadolinium

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 918
Author(s):  
Boris Straumal ◽  
Natalia Martynenko ◽  
Diana Temralieva ◽  
Vladimir Serebryany ◽  
Natalia Tabachkova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Fine Particles ◽  
Volume Fraction ◽  
Galvanic Corrosion ◽  
Angular Pressing ◽  
Average Grain Size ◽  
The Matrix ◽  
Mechanical Properties And Corrosion

The effect of equal channel angular pressing (ECAP) on the microstructure, texture, mechanical properties, and corrosion resistance of the alloys Mg-6.0%Ag and Mg-10.0%Gd was studied. It was shown that ECAP leads to grain refinement of the alloys down to the average grain size of 2–3 μm and 1–2 μm, respectively. In addition, in both alloys the precipitation of fine particles of phases Mg54Ag17 and Mg5Gd with sizes of ~500–600 and ~400–500 nm and a volume fraction of ~9% and ~8.6%, respectively, was observed. In the case of the alloy Mg-6.0%Ag, despite a significant grain refinement, a drop in the strength characteristics and a nearly twofold increase in ductility (up to ~30%) was found. This behavior is associated with the formation of a sharp inclined basal texture. For alloy Mg-10.0%Gd, both ductility and strength were enhanced, which can be associated with the combined effect of significant grain refinement and an increased probability of prismatic and basal glide. ECAP was also shown to cause a substantial rise of the biodegradation rate of both alloys and an increase in pitting corrosion. The latter effect is attributed to an increase in the dislocation density induced by ECAP and the occurrence of micro-galvanic corrosion at the matrix/particle interfaces.

scholarly journals Post-FSW Cold-Rolling Simulation of ECAP Shear Deformation and Its Microstructure Role Combined to Annealing in a FSWed AA5754 Plate Joint

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1526 ◽  
Author(s):  
Marcello Cabibbo ◽  
Chiara Paoletti ◽  
Mohamed Ghat ◽  
Archimede Forcellese ◽  
Michela Simoncini
Keyword(s):  
Cold Rolling ◽  
Shear Deformation ◽  
Volume Fraction ◽  
Base Material ◽  
Sheet Thickness ◽  
Annealing Treatment ◽  
Grain Structure ◽  
Friction Stir ◽  
Size Refinement ◽  
Angular Pressing

Friction stir welds are considered reliable joints for their lack of voids, cracks and distortions. When compared to the base material, friction stir welding (FSW) joints typically exhibit finer grain structured (especially at the nugget zone, NZ). Similarly, refined grain structure can also be obtained by severe plastic deformation (SPD) techniques, such as equal channel angular pressing (ECAP). In fact, the fine grain structures produced within the NZ of FSW or friction stir processed (FSP) materials are usually coarser than the ones achieved by ECAP. The former is characterized by lower dislocation density, higher high-angle boundary fraction and different mechanical strength, compared to what can be obtained by ECAP. In this study, a dedicated cold-rolling (CR) set-up, specifically designed to simulate an ECAP-equivalent shear deformation, was used to further refine the grain structure of FSW AA5754 sheets. The effect of ECAP-equivalent deformation induced by CR in a 2 mm-thick AA5754-H111 FSW joint was investigated. FSW was carried out at two different rotational (ω) and translational (v) welding speeds, 600 rpm, 200 mm/min and 1800 rpm, 75 mm/min, respectively. FSW sheets were then CR to obtain an equivalent shear strain of ε ~ 1.08, that is equivalent to 1-ECAP pass carried out with an internal die channels intersecting at an angle φ = 90° with a curvature extending over an angle Ψ = 20°. By CR, the sheet thickness reduced only by ~20%. The role of annealing on the FSW and CR plastically deformed AA5754 was also investigated. This was applied either prior or after FSW, and it resulted that whenever it follows the FSW, the mean volume fraction of dispersoids and Mg-rich particles is higher than the case of annealing preceding the FSW process. On the contrary, it was found that the annealing treatment had a minimal role on the dispersoids and particles mean size. The here reported post-FSW ECAP-simulated deformation, obtained by a customized CR process, showed sheet integrity and a significant concurrent grain size refinement.

Equal Channel Angular Pressing of Al Alloy AA2219

2009 ◽  
Vol 67 ◽  
pp. 53-58
Author(s):  
V. Anil Kumar ◽  
M.K. Karthikeyan ◽  
Rohit Kumar Gupta ◽  
P. Ramkumar ◽  
P.P. Sinha
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
High Strength ◽  
Dark Field ◽  
Grain Structure ◽  
Al Alloy ◽  
Angular Pressing

Severe plastic deformation processes (SPD) are gaining importance as advanced materials processing techniques and hold immense potential in obtaining ultra fine-grained high strength materials. Among the SPD techniques, Equal channel angular pressing (ECAP) has its own merits to produce materials with ultra fine grains in bulk with better mechanical properties. The material deforms with high level of plastic strain inside the channel resulting in grain refinement of the output material with improvement in mechanical properties. A very viable die configuration was conceptualized and die was made with 1200 channel angle. Processing of 25 mm dia. of Al alloy AA2219 at room temperature was successfully carried out and grain refinement was observed. The mechanism of grain refinement has been studied using optical and transmission electron microscopy (TEM). It was observed that low energy dislocation structure (LEDS) forms concurrently with sub-grain structure due to dislocation rearrangements, which provide stability to the evolving sub-grain structure. Dislocation mobility is hindered by the presence of precipitates and / or intermetallic dispersoids present in the matrix and results in presence of dislocations in grain interiors. The pile up of dislocations at intermetallic dispersoids was confirmed from the dark field TEM micrographs. Present paper describes the experimental procedure and followed to attain severe plastic deformation through ECAP. Increase in hardness as well as refinement in the grain size after 5-passes have been discussed in light of extensive optical and TEM. The mechanisms of grain refinement to achieve nano-grained structure and strengthening accrued from the grain refinement through ECAP has been discussed.

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