Manufacturing and mechanical characterization of Mg-4Y-2Nd-0.4Zr-0.25La magnesium microtubes by combined severe plastic deformation process for biodegradable vascular stents

Using biodegradable magnesium microtubes for producing vascular stent have received a great deal of attention during the last decade. However, poor workability and low mechanical properties of Mg and its alloys pose an obstacle to manufacturing microtubes for stent application. In this article, a combined method including equal channel angular pressing), direct extrusion, and microtube extrusion processes are employed to produce WE43 magnesium microtubes. Thus, microtubes with an outside diameter of 3.3 mm and a wall thickness of 0.22 mm are successfully manufactured. The results demonstrate a significant improvement in mechanical properties and microstructure of the processed samples. The ultimate strength and elongation are increased from 240 MPa and 6% to 340 MPa and 20% in the final microtube, respectively. In addition, the microhardness of the final microtube is enhanced from an initial value of 85 Hv to 102 Hv and the grain size is reduced to 3.5 µm from the initial value of 135 µm. Therefore, the proposed method overcomes the poor formability of Mg alloy and can be used to fabricate high-strength microtubes with ultrafine-grained structure.

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Mechanical and Microstructural Characterization of Al-6082 Ultrafine-Grained Alloys Processed by ECAP Combined with Traditional Forming Techniques

Materials Science Forum ◽

10.4028/www.scientific.net/msf.589.111 ◽

2008 ◽

Vol 589 ◽

pp. 111-116 ◽

Cited By ~ 5

Author(s):

György Krállics ◽

Arpad Fodor ◽

Jenő Gubicza ◽

Z. Fogarassy

Keyword(s):

Mechanical Properties ◽

Equal Channel Angular Pressing ◽

Microstructural Characterization ◽

Shape Rolling ◽

Rotary Forging ◽

Angular Pressing ◽

Ultrafine Grained ◽

Forming Methods

An Al-6082 alloy was subjected to equal channel angular pressing (ECAP) and subsequently to conventional forming methods such as shape rolling and rotary forging. The effect of different deformation techniques on the microstructure and the mechanical properties was studied. It was found that the shape rolling and rotary forging increased further the strength of ECAP-processed samples and induced a loss of ductility.

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Influence of Severe Plastic Deformation on Mechanical Properties of an AA5024 Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.1317 ◽

2016 ◽

Vol 879 ◽

pp. 1317-1322 ◽

Cited By ~ 3

Author(s):

Anna Mogucheva ◽

Diana Yuzbekova ◽

Tatiana Lebedkina ◽

Mikhail Lebyodkin ◽

Rustam Kaibyshev

Keyword(s):

Mechanical Properties ◽

Plastic Deformation ◽

Severe Plastic Deformation ◽

High Strength ◽

Coarse Grained ◽

Type B ◽

Angular Pressing ◽

Ultrafine Grained ◽

Elongation To Failure ◽

Dislocation Strengthening

The paper reports on the effect of severe plastic deformation on mechanical properties of an Al-4.57Mg-0.35Mn-0.2Sc-0.09Zr (in wt. pct.) alloy processed by equal channel angular pressing followed by cold rolling (CR). The sheets of the 5024 alloy with coarse grained (CG) structure exhibited a yield stress (YS) near 410 MPa and an ultimate tensile strength (UTS) of 480 MPa, while the YS and UTS of this material with ultrafine-grained (UFG) structure increased to 530 and 560 MPa, respectively. On the other hand, the elongation to failure decreased by a factor of 2 and 4 after CR and CR following ECAP, respectively. It was shown that dislocation strengthening attributed to extensive CR plays a major role in achieving high strength of this alloy. Besides these macroscopic characteristics, jerky flow caused by the Portevin-Le Chatelier (PLC) instability of plastic deformation was examined. The formation of UFG structure results in a transition from mixed type A+B to pure type B PLC serrations. No such effect on the serrations type was observed after CR.

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The New Approach to Produce Al Sheets with UFG Structure Using SPD Processing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.584-586.176 ◽

2008 ◽

Vol 584-586 ◽

pp. 176-181

Author(s):

N.F. Yunusova ◽

Rinat K. Islamgaliev ◽

I.F. Safiullin ◽

Ruslan Valiev

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

High Strength ◽

Short Term ◽

New Approach ◽

Rolled Material ◽

Angular Pressing ◽

Ultrafine Grained ◽

Low Temperature Aging ◽

Temperature Aging

Microstructure and mechanical properties of the ultrafine-grained (UFG) 1421 aluminum alloy processed by equal channel angular pressing (ECAP) have been studied. This UFG material was successfully rolled under the conditions of superplasticity. It was established that the rolled material exhibited not only the enhanced superplasticity, but also high strength retaining initial ductility at room temperature after additional short-term annealing and low-temperature aging.

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Equal Channel Angular Pressing and Characterization of a Patented Eutectoid Fe-C Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1012.360 ◽

2020 ◽

Vol 1012 ◽

pp. 360-365

Author(s):

Yasmim Caroline Brito ◽

Barbara Woinarovicz Ramos ◽

Selauco Vurobi Junior ◽

Ricardo Sanson Namur ◽

Osvaldo Mitsuyuki Cintho

Keyword(s):

High Strength ◽

Mechanical Tests ◽

Metallographic Analysis ◽

Ecap Processing ◽

Single Pass ◽

Hardness Level ◽

Angular Pressing ◽

Ultrafine Grained ◽

Patented Steel

Equal Channel Angular (ECAP) pressing has been showed as an attractive route to produce fine and ultrafine-grained metals and alloys with high strength and fracture toughness. ECAP is a simple process for applying severe plastic deformation (SPD) to metals that can be done with common laboratory equipments (mechanical tests machines) and an adequate die. In the present work, an eutectoid steel was processed by ECAP in a 120° die. Mechanical behavior of samples deformed by ECAP was compared to the same material processed by rolling. The hardness level obtained after a single pass of ECAP was comparable to an 84% reduction by rolling in a single pass. The hardness level obtained after 1 ECAP pass on a patented steel was higher than 4 ECAP passes on the same steel without patenting. The metallographic analysis showed intense alterations on the microstructure by the ECAP processing.

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Influence of Annealing on the Structure and Mechanical Properties of Ultrafine-Grained Alloy Ti-6Al-7Nb, Processed by Severe Plastic Deformation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.667-669.943 ◽

2010 ◽

Vol 667-669 ◽

pp. 943-948 ◽

Cited By ~ 10

Author(s):

Veronika Polyakova ◽

Irina P. Semenova ◽

Ruslan Valiev

Keyword(s):

Mechanical Properties ◽

Plastic Deformation ◽

Severe Plastic Deformation ◽

Equal Channel Angular Pressing ◽

Human Body ◽

High Strength ◽

Point Of View ◽

Angular Pressing ◽

Ultrafine Grained ◽

Strength And Ductility

This work is devoted to enhancement of strength and ductility of the Ti-6Al-7Nb ELI alloy, which is less harmful from medical point of view for human body in comparison to Ti-6Al-4V. It has been demonstrated that formation of an ultrafine-grained structure in the alloy with the help of equal-channel angular pressing in combination with heat and deformation treatments allows reaching high strength (UTS = 1400 MPa) and sufficient ductility (elongation 10 %).

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Determination of Mechanical Properties on Aluminium with 5% Copper Powder Metallurgy Route Compacts through Equal Channel Angular Pressing

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.813-814.161 ◽

2015 ◽

Vol 813-814 ◽

pp. 161-165

Author(s):

M. Sadhasivam ◽

T. Pravin ◽

S. Raghuraman

Keyword(s):

Mechanical Properties ◽

Plastic Deformation ◽

Grain Size ◽

Severe Plastic Deformation ◽

Equal Channel Angular Pressing ◽

High Strength ◽

Angular Pressing ◽

Fine Grain ◽

Plastic Deformation Process

The need for super-plasticity and high strength leads to the development of Severe Plastic Deformation technique. The strength of the material is directly dependent upon the grain size of the material. So, there is a need for producing Ultra-Fine Grain microstructure (UFG). UFG material is the material with very small grain size in the range of sub-micrometre. Application of severe plastic deformation, imparts extremely high strain. Equal channel angular pressing (ECAP) is a severe plastic deformation process in which the metal specimen is pressed through an angular channel of equal cross section. The material is subjected to shear deformation and strain is imparted in the specimen. Geometric parameters such as channel angle and corner angle play a major role in grain refinement. Aluminium (Al) specimens are subjected to undergo severe plastic deformation. Since, the strength of Al is not high, other materials are added in order to enhance its mechanical properties by matrix work hardening. Copper (Cu) along with Al shows increase in its strength and also in hardness. An attempt is made with Aluminium and copper, blended in the ratio 95:5 by weight with the main objective to study the Tensile strength, Hardness and Percentage Elongation properties of the specimen.

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Mechanical Properties and Aging Behavior of Ultrafine Grained Al-Ag Alloy Fabricated by Accumulative Roll-Bonding

Materials Science Forum ◽

10.4028/www.scientific.net/msf.794-796.851 ◽

2014 ◽

Vol 794-796 ◽

pp. 851-856

Author(s):

Tadashiege Nagae ◽

Nobuhiro Tsuji ◽

Daisuke Terada

Keyword(s):

Mechanical Properties ◽

Grain Refinement ◽

Accumulative Roll Bonding ◽

Precipitation Hardening ◽

Tensile Elongation ◽

Solution Treatment ◽

High Strength ◽

Subsequent Aging ◽

Roll Bonding ◽

Ultrafine Grained

Accumulative roll-bonding (ARB) process is one of the severe plastic deformation processes for fabricating ultrafine grained materials that exhibit high strength. In aluminum alloys, aging heat treatment has been an important process for hardening materials. In order to achieve good mechanical properties through the combination of grain refinement hardening and precipitation hardening, an Al-4.2wt%Ag binary alloy was used in the present study. After a solution treatment at 550°C for 1.5hr, the alloy was severely deformed by the ARB process at room temperature (RT) up to 6 cycles (equivalent strain of 4.8). The specimens ARB-processed by various cycles (various strains) were subsequently aged at 100, 150, 200, 250°C, and RT. The hardness of the solution treated (ST) specimen increased by aging. On the other hand, hardness of the ARB processed specimen decreased after aging at high temperatures such as 250°C. This was probably due to coarsening of precipitates or/and matrix grains. The specimen aged at lower temperature showed higher hardness. The maximum harnesses achieved by aging for the ST specimen, the specimens ARB processed by 2 cycles, 4 cycles and 6 cycles were 55HV, 71HV, 69HV and 65HV, respectively. By tensile tests it was shown that the strength increased by the ARB process though the elongation decreased significantly. However, it was found that the tensile elongation of the ARB processed specimens was improved by aging without sacrificing the strength. The results suggest that the Al-Ag alloy having large elongation as well as high strength can be realized by the combination of the ARB process for grain refinement and the subsequent aging for precipitation hardening.

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Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations

Materials Science Forum ◽

10.4028/www.scientific.net/msf.503-504.31 ◽

2006 ◽

Vol 503-504 ◽

pp. 31-36 ◽

Cited By ~ 17

Author(s):

Johannes Mueller ◽

Karsten Durst ◽

Dorothea Amberger ◽

Matthias Göken

Keyword(s):

Mechanical Properties ◽

Strain Rate ◽

Strain Rate Sensitivity ◽

Room Temperature ◽

Rate Sensitivity ◽

Strain Rates ◽

Fcc Metals ◽

Angular Pressing ◽

Ultrafine Grained ◽

Indentation Strain

The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.

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