Microstructure and hardness inhomogeneity of fine-grained AM60 magnesium alloy subjected to cyclic expansion extrusion (CEE)

Amani, Soheil; Faraji, Ghader; Abrinia, Karen

doi:10.1016/j.jmapro.2017.06.007

Cited by 51 publications

(11 citation statements)

References 55 publications

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“…This is in good agreement with the observed changes in hardness of other SPD techniques. 46,47 Also, there is a small increase in hardness after the extrusion process. The increase in the hardness can be due to the grain refinement 48 because it is commonly accepted that materials with HCP structure such as magnesium alloys show a high grain size dependency of strength and hardness due to the lack of slip systems.…”

Section: Resultsmentioning

confidence: 99%

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

Amani

Faraji

Mehrabadi

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part B:

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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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Section: Resultsmentioning

confidence: 99%

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

Amani

Faraji

Mehrabadi

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…As it can be seen, the surface appearance in the processed side of the sample is getting better due to the frictionless characteristic of HCEE process. The maximum length/diameter of the sample which could be produced via conventional CEC or CEE is below 5 [19] while this value was successfully…”

Section: Resultsmentioning

confidence: 99%

“…The amount of equivalent plastic strain after one pass of HCEE process can be calculated from Eq. 1 [16] as ̃≈ 1.34 though the distribution of strain is almost complex in reality [31].…”

Section: Resultsmentioning

confidence: 99%

“…This would be the major setback of the method, remaining at a laboratory scale. Until now, the maximum length/diameter ratios of CEE or CEC samples are below 5, making these processes unsuitable for industrial applications [19,20], moreover, most spd techniques such CEE cause heat to form due to deformation of the plastic, but this method maybe prevent heat and dynamic recovery in the process due to the presence of fluid. In addition, strain rate can more than CEE process because friction force is very little, so times of process is less than other techniq [21,22].…”

Section: Introductionmentioning

confidence: 99%

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Hydrostatic cyclic expansion extrusion (HCEE) as a novel severe plastic deformation process for producing long nanostructured metals

Samadpour

Faraji

Babaie

et al. 2018

Materials Science and Engineering: A

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In this paper, hydrostatic cyclic expansion extrusion (HCEE) is developed as a new severe plastic deformation technique for processing of the relatively longer ultrafine grained samples. Increasing the length of the processed sample, decreasing the processing load astonishingly, and increasing the hydrostatic stresses are the main advantages of HCEE. In This process lubricant surrounded around workplaces plays the main role in reducing the friction load and increase pressure hydrostatic. HCEE process was executed to commercial pure aluminum 1050 at room temperature, and microstructural evolution and the mechanical properties were examined. Microstructure evolution of this process was investigated by transmission electron microscopy (TEM) and back-scattered diffraction (EBSD). TEM and EBSD revealed an ultrafine grained microstructure after the two passes of the HCEE process. The average size of grains and subgrain decreased from 50µm in the annealed sample to 0.76µm after two passes of the process. Mechanical properties such strength and hardness improved because of the large effect strain. Yield and ultimate strength were increased from 40 MPa and 52 MPa to 109 MPa and 115 MPa just after one pass of HCEE process, also Microhardness was increased from 36 HV to 45 HV at first passes.

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“…For obtaining bulky materials with much finer grains, a variety of efforts have been made for a long time. Severe plastic deformation (SPD) is known as one of the promising methods for achieving ultrafine grain sizes smaller than 1 μm, through accumulating lattice defects in materials by applying extremely large plastic deformation (Stolyarov et al, 2001;Tsuji et al, 2002;Son et al, 2005;Azushima et al, 2008;Okayasu et al, 2008;Tsuji et al, 2008;Calcagnotto et al, 2010;Mohamed et al, 2015;Amani et al, 2017). However, most SPD processes do not seem applicable to practical manufacturing in large scales, due to their complicated procedures, limited dimensions of specimens and huge metal-working forces required.…”

Section: Introductionmentioning

confidence: 99%

Challenging Ultra Grain Refinement of Ferrite in Low-C Steel Only by Heat Treatment

2020

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It is well-known that grain refinement is one of the most effective ways to improve strength of metals without addition of alloying elements. In order to obtain bulky metals having ultrafine grained (UFG) microstructures with average grain sizes smaller than 1 μm, severe plastic deformation (SPD) processes have made a great success. However, there are still big barriers to realize UFG metallic materials, especially UFG steels, in large scale industries, since severe plastic deformation processes usually need special techniques and equipment, and large deformation forces are required for heavy plastic deformations. Cyclic heat treatments to repeat martensitic transformation and austenitization have been known as a simple way to fabricate fine-grained austenitic structures in steels. In the present study, we tried to make final ferrite microstructures ultrafine in a low-C steel by means of the cyclic heat treatment. Evolution of microstructures during the cyclic heat treatment was systematically investigated, putting stress on the change of grain sizes of austenite and ferrite. The austenite grain size decreased with increasing the number of heat treatment cycles, and the minimum average austenite grain size obtained was 11 μm. By having furnace-cooling from austenite states with various grain sizes, ferrite microstructures with different mean grain sizes were fabricated. We could successfully obtain a fine-grained ferrite structure with a mean grain size of 4.5 μm and nearly a random texture through the heat treatment without deformation. Microstructural features and mechanical properties of the obtained fine-grained ferritic structures were investigated by scanning electron microscope/electron back-scattering diffraction measurements and a tensile test at room temperature. The specimens with ferrite + pearlite microstructure with the smallest average ferrite grain size of 4.5 μm managed both high strength (yield strength of 375 MPa and tensile strength of 500 MPa) and large tensile ductility (uniform elongation of 20% and total elongation of 39%) in the simple 2Mn-0.1C steel.

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Microstructure and hardness inhomogeneity of fine-grained AM60 magnesium alloy subjected to cyclic expansion extrusion (CEE)

Cited by 51 publications

References 55 publications

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

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

Hydrostatic cyclic expansion extrusion (HCEE) as a novel severe plastic deformation process for producing long nanostructured metals

Challenging Ultra Grain Refinement of Ferrite in Low-C Steel Only by Heat Treatment

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