Mechanical and Structural Properties of High Purity Al Processed by ECAP

Kvačkaj, Tibor; Kočiško, Róbert; Pokorný, Imrich; Bidulská, Jana; Kvačkaj, Michal; Kováčová, Andrea; Bidulský, Róbert; Lityńska‐Dobrzyńska, Lidia

doi:10.12693/aphyspola.122.557

Cited by 4 publications

(5 citation statements)

References 14 publications

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“…8 the hardness increases by aproximately a factor of two after 2 passes and thereafter the microhardenss continues to rise but to a smaller amounts. These trends are generally consistent with earlier data where the hardness measurements were taken on X plane [11,17,18]. Earlier studies demonstrated there is a good correlation between the values recorded in microhardness measurements and the internal microstructures within the material [19][20][21].…”

Section: Fig7 Vickers Micro-hardness Vs Ecap Passessupporting

confidence: 91%

“…Thus, by taking measurements along linear traverses it is possible to obtain quantitative information on the variations of hardness and homogeneity on selected planes of sectioning after ECAP. In the last decades several studies focused on the mechanical behavior and the microstructural evolution of pure Al and Al alloys processed by ECAP [6][7][8][9][10][11][12][13][14][15]. However, very little information is available at present on the evolution of microhardness and on degree of homogeneity existing along the orthogonal and longitudinal axes of billets processed by ECAP [17,18], although this information is important if the pressed billets will be used in industrial application.…”

Section: Introductionmentioning

confidence: 99%

“…The present research was undertaken with the objective to use microhardness measurements to evaluate the level of homogeneity within the pressed sample of AA 3004, processed by ECAP. Earlier investigations, conducted on samples processed by either ECAP [10][11][12][13][14][15] or high-pressure torsion (HPT) [21], demonstrated a direct correlation between microhardness measurements and the average grain sizes determined using transmission electron microscopy. Accordingly, it is reasonable to anticipate that a homogeneity in the hardness measurements will correspond also to a reasonable homogeneity in the internal microstructure.…”

Section: Introductionmentioning

confidence: 99%

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MICRO-HARDNESS EVOLUTION OF Al-ALLOY AA 3004, PROCESSED BY EQUAL CHANNEL ANGULAR PRESSING

Izairi¹,

Ajredini²,

Ristova³

et al. 2013

Acta Metall Slovaca

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Equal Channel Angular Pressing (ECAP) is a very interesting method for modifying the microstructure in producing materials with ultrafine grain in sub-micrometer or nanometre range. Experiments demonstrate that these ultrafine structures may exhibit, by comparison with large -grained polycrystals, major differences in some fundamental properties. A nanostructured AA 3004 alloy was used to investigate the evolution of microhardness and microstructure on the cross-sectional plane X, after processing by ECAP at room temperature for up to six passes. The measurements show the average microhardness increases significantly after two passes with additional increases in subsequent passes. Microhardness values increase by more than two times after 6 passes. There is a reduction in grain size from of ~ 50µm in the initial condition to ~ 12 µm after 6 passes. The results also show that the microstructure and the microhardness evolve with increasing strain so that, after a total of 6 passes, the structure is almost homogenous throughout the cross-sectional plane of the billet.Keywords: Al alloy; SPD; ECAP; micro-hardness; homogeneity IntroductionExtensive studies of equal-channel angular pressing (ECAP) and other severe severe plastic deformation (SPD) techniques, over the past two decades [1][2][3] have established the processing techniques and have shown the possibility of producing ultrafine grain (UFG) structure in many metals and alloys. Grain size reduction is one of the most attractive ways of improving the mechanical properties of metallic materials. It is known that the strength of all polycrystalline materials is related to the grain size, through the Hall-Petch equation which predict an increase in yield strength (σ y ) with a decrease in grain size (d): σ y = σ 0 + kd -1/2 [4,5]. Several different SPD procedures are now available but the most popular appears to be Equal Channel Angular Pressing (ECAP), that was first proposed in the 80 s, by Segal. In processing by ECAP the sample is pressed through a die containing two channels equal in cross-section, intersecting at an angle φ that is generally close to 90 o (Fig. 1). Since the sample emerges from

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Section: Fig7 Vickers Micro-hardness Vs Ecap Passessupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

MICRO-HARDNESS EVOLUTION OF Al-ALLOY AA 3004, PROCESSED BY EQUAL CHANNEL ANGULAR PRESSING

Izairi¹,

Ajredini²,

Ristova³

et al. 2013

Acta Metall Slovaca

View full text Add to dashboard Cite

show abstract

“…By measuring the microhardness (HV) along linear traverses on the sample, it is possible to obtain quantitative information on the variations in the hardness and homogeneity on selected planes. In the last decades, several studies focused their examination on the mechanical behavior and the microstructural evolution of pure Al and Al-alloys processed by ECAP [13][14][15][16][17]. However, very little information is available about the evolution of microhardness and the degree of homogeneity along the orthogonal and longitudinal axes of billets processed by ECAP [16], although this information is crucial for the industrial application.…”

Section: Introductionmentioning

confidence: 99%

Archives of Metallurgy and Materials

Izairi¹,

Ajredini²,

Vevecka-Pfiftaj³

et al. 2018

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Equal-channel angular pressing (ECAP) was used as a technique for severe plastic deformation (SPD) on Al alloy AA3004. This technique produced fully dense materials of refined grain structure to sub-micrometer dimensions and advanced mechanical properties. The ECAP processing of samples was conducted as 1 to 4 passes through the die at room temperature. We present the results of the studied homogeneity evolution with the ECAP treatment. Furthermore, a Scanning Electron Microscope (SEM) was used for examination of the microstructure changes in samples undergone from 1 to 4 passes. The microhardness-HV increased upon each ECAP pass. The resulting micro-hardness evolution was attributed to crystalline microstructure modifications, such as the d-spacing (studied by X-ray Diffraction-XRD) depending on the number of ECAP pressings. The microcrystalline changes (grain refining evaluated from the Scanning Electron Microscopy -SEM images) were found to be related to the HV, following the Hall-Petch equation.

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“…The small punch test (SPT) method was applied in the study of pure aluminium after severe plastic deformation by equal channel angular pressing (ECAP). SPT is using miniature discs specimens of 8 mm in diameter and 0.5 mm thickness [1] and can be used for determining various mechanical properties from very small volume of materials: creep [2][3][4][5][6], static [7][8][9][10][11][12][13][14][15][16] and fracture [17][18][19][20][21]. In these tests, a small punch with a spherical head penetrates through the disc specimen into a receiving hole.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Fracture in Pure Aluminium After Ecap by Means of Small Punch Test

Dymáček¹,

Dobeš²,

Král³

et al. 2013

Acta Metall. Slovaca Conf.

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The properties of pure 99.99% aluminium after severe plastic deformation by equal channel angular pressing (ECAP) with low (1, 2) and high (4, 6, 12) number of passes were investigated. The constant-deflection mode of the small punch test was used to compare the mechanical behaviour. The advantages of the test are that smaller amount of material is needed and the sample preparation is easier. Characteristic points as yield force and maximum force were evaluated from the recorded dependence of force vs. deflection. A possibility of their conversion into variables of conventional tensile test is discussed. Fracture energy was calculated from this dependence. The tests were performed at both room temperature and elevated temperatures up to 300 °C. The appearance of fracture surfaces was observed by scanning electron microscopy. The tendency for increased strength of ECAPed Al in comparison with virgin Al was notable at room as well at elevated temperatures. The number of ECAP passes that gave Al with the greatest strength were however not the highest number of passes (12) but 1 or 2 passes depending on testing temperature. Higher numbers of ECAP passes showed stagnation and slight decrease of the strength of ECAPed Al.

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Mechanical and Structural Properties of High Purity Al Processed by ECAP

Cited by 4 publications

References 14 publications

MICRO-HARDNESS EVOLUTION OF Al-ALLOY AA 3004, PROCESSED BY EQUAL CHANNEL ANGULAR PRESSING

MICRO-HARDNESS EVOLUTION OF Al-ALLOY AA 3004, PROCESSED BY EQUAL CHANNEL ANGULAR PRESSING

Archives of Metallurgy and Materials

Investigation of Fracture in Pure Aluminium After Ecap by Means of Small Punch Test

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