Top PDF The Effect of Equal Channel Angular Pressing (ECAP) on the Microstructure and Hardness of A356 Aluminium Alloy

The Effect of Equal Channel Angular Pressing (ECAP) on the Microstructure and Hardness of A356 Aluminium Alloy

The Effect of Equal Channel Angular Pressing (ECAP) on the Microstructure and Hardness of A356 Aluminium Alloy

The image analysis of each sample was done using Image-J software to find area and perimeter of the particles in order to calculate its shape factor and average grain size. Figure 5 displays the average grain size of α- Al particles and its shape factor at different condition of processing. As-cast sample exhibited the lowest shape factor with value of 0.5123 and larger average grain size of 110.4μm as there are many dendrite structures found in as-cast sample as shown in Figure 4. The shape factor is a dimensionless quantities used in image analysis to describe the shape of particle where this work focused on spherical shape. Shape factor near to 1 showed the best result in obtaining spherical microstructure. Based on the result, a sample with cooling slope showed the highest shape factor of 0.82. The average grain size of a sample with cooling slope was reduced to 75.37μm from 110.463μm of as-cast sample. It was proven that the α- Al particles of the sample with CS become globular as the dendrite arms are fragmented due to shearing force on the CS plate [18]. On the other hand, it was also observed that the average grain size of α- Al particles of cast samples were refined after ECAP process. As-cast sample in combination with ECAP has an average size of 96.3μm from 110.463μm in as-cast sample. Moreover, the cooling slope sample after being processed by ECAP showed an improvement in terms of the grain size. The grain size was reduced from 75.37μm to 58.25μm with a reduction of approximately 22.7%. It was proven that cooling slope ECAPed gave finer grain size as compared to as-cast ECAPed.
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Effect Of Heat Treatment And Equal Channel Angular Pressing On The Microstructures, Hardness And Wear Resistance Of A356 Aluminium Alloy With Tib2

Effect Of Heat Treatment And Equal Channel Angular Pressing On The Microstructures, Hardness And Wear Resistance Of A356 Aluminium Alloy With Tib2

Pemprosesan 4-turutan ECAP meningkatkan kekerasan dengan ketara spesimen yang mempunyai matriks relatif lembut. Matriks yang relatif lembut dalam gabungan dengan zarah TiB 2 [r]

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Effect Of Heat Treatment On Mechanical Properties  Of Equal Channel Angular Pressing (ECAP) Processed A356 Aluminium Alloy

Effect Of Heat Treatment On Mechanical Properties Of Equal Channel Angular Pressing (ECAP) Processed A356 Aluminium Alloy

Equal-channel angular pressing (ECAP) is a severe plastic deformation process (SPD) that use to obtain ultrafine grain material. According to (Langdon, 2017) ECAP is a severe plastic deformation technique that capable of presenting severe plastic strain bulk metals, leading to substantial grain refinement to submicrometer or even to nanometer level. A simple sheer force is apply when a metal is subjected to an intense plastic straining. The force apply is not create any changing in cross-section dimension of the sample. ECAP introduce ultrafine grained microstructure at low homologous temperature.
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Equal Channel Angular Pressing of Aluminium Alloy 5083 using different die geometries

Equal Channel Angular Pressing of Aluminium Alloy 5083 using different die geometries

out to estimate the influence of process parameters namely die channel angle, number of passes, processing routes on microstructure and mechanical properties of AA 5083 samples. Micro-structural analysis has been performed using Optical Microscope to study the initial grain size, grain refinement. Vickers micro-hardness tests were conducted to observe the effect of ultrafine grains formed during ECAP. It is cleared from the results that microstructure and mechanical properties were highly improved after third pass when the billets were pressed in route B C through the dies having the channel angle of 105 0 .
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Equal Channel Angular Pressing as a New Processing to Control the Microstructure and Texture of Metallic Sheets

Equal Channel Angular Pressing as a New Processing to Control the Microstructure and Texture of Metallic Sheets

Embury et al. [10] described that strain-path change influences recrystallisation in three ways, i.e., 1) The pattern of flow during deformation and resulting spatial distribu- tion of recrystallisation; 2) The work hardened state, name- ly dislocation density and structures; and 3) the introduc- tion of localised shear bands, which perturb the existing deformed structures. The first effect can be ruled out since the change of flow pattern should lead to a drastic change in the cold-rolled texture. Indeed, {100}//ND orientation became stronger in the cold-rolled texture in the ECAP process. This orientation, however, is rather recrystallisa- tionresistant. Thus, in this context, texture change is not directly associated with enhanced recrystallisation. The second effect is directly associated with the energy stored by substructure. Since hardness before the final annealing is almost equal in the two processes, as shown in Figure 5, the difference in the stored energy is not large enough to become a factor enhancing recrystallisation kinetics. Therefore, the third effect by grain-scale MSB may become the most influential one as a result of the strain path change combining one-pass ECAP and cold-rolling. It is well estabmlished that the localized shear band serves as a preferential nucleation site [9,25].
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Effect of equal channel angular pressing processing routes on corrosion resistance and hardness of heat treated A356 alloy

Effect of equal channel angular pressing processing routes on corrosion resistance and hardness of heat treated A356 alloy

As it is clear from this figure, the average of hardness values is increased with increasing the pass number. After the second ECAP passes, the microstructure is still in of inhomogeneous and the appearance of the dendritic form was disappearance, the primary α-Al phase tended to be sheroidising via route Bc while elongated shape via route A and the Si particles became a fragmented result of increase in hardness in all samples. Also, it has been reported that with imposing deformation, brittle and hard eutectic Si particles are broken and with increasing the deformation, their mean free space becomes smaller. Since the strength is inversely related to the mean free space of particles, the hardness values of samples are increased with increasing the pass number (Haghshenas & Sabetghadam 2009; Haghshenas et al. 2009). Three passes of ECAP route Bc and four passes of ECAP route A increased the hardness of both samples due to the fragmentation of eutectic Si particles, the reduction in grain size, and aging process. The homogenous distribution of Si particles and primary α-Al phase of the ECAPed route A plays an integral role in improving the hardness of ECAPed materials.
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Effect of multidirectional forging and equal channel angular pressing on ultrafine grain formation in a Cu-Cr-Zr alloy

Effect of multidirectional forging and equal channel angular pressing on ultrafine grain formation in a Cu-Cr-Zr alloy

subsequent aging treatment at 450 °C for 1 h (peak aged conditions). The multidirectional forging (MDF) and the equal channel angular pressing (ECAP) were chosen as methods of large plastic deformation. The plastic deformations were carried out under isothermal conditions at 400 °C to various total strains up to 4. The dies were preheated using high temperature furnaces and the temperature was controlled automatically with accuracy of ± 2°. The samples with starting dimensions of 25 mm × 20 mm × 16 mm were machined for MDF. The MDF was carried out with consequent change in the deformation axis through 90° from pass to pass. The true strain applied in each pass was about 0.4 and a strain rate was approximately 10 -3 s -1 . After each forging pass, the samples were water quenched and then reheated to the test temperature during 15 min. The billets of 14 mm × 14 mm × 90 mm were subjected to ECAP via route B C (90° anticlockwise rotation of the specimens after each pass) at a strain rate of 1 s -1 . The samples for ECAP were preheated during 30 min. A die angle of 90° was chosen that resulted in a true strain of about 1 at each pass. The deformed samples were quenched in water after complete ECAP cycle, i.e. after reaching the desired total strain. The microstructure of deformed samples was examined by a Quanta 600 FEG scanning electron microscope (SEM) equipped with an electron backscattering diffraction (EBSD) analyzer incorporating an orientation imaging microscopy (OIM) and a Jeol JEM- 2100 transmission electron microscope. The strain hardening was measured by means of microhardness tests. The microhardness tests were carried out using a WOLPERT 420MVD with a load of 300 g and holding time of 10 s. The microstructural investigations were performed on the sections parallel to the final forging axis for the MDF samples and on the Y plane or flow plane parallel to the side face at the point of exit from the die [11] for the ECAP samples. The samples for SEM observations were mechanically polished on 1000 grit SiC paper with subsequent electropolishing using an electrolyte of HNO3:CH3OH=1:3 at room temperature with a voltage of 10 V. The step size for EBSD scanning was 100 nm for the samples strained to a total strain of around 1, and 60 nm for the samples processed to total strains of 2 and 4. An average grain size was estimated by linear intercept method as a distance between high-angle boundaries on the obtained EBSD maps. The fraction of ultrafine grains (UFG) was obtained using OIM software (EDAX TSL, version 5.2).
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Influence of Processing Regimes on Fine Grained Microstructure Development in an Al Mg Sc Alloy by Hot Equal Channel Angular Pressing

Influence of Processing Regimes on Fine Grained Microstructure Development in an Al Mg Sc Alloy by Hot Equal Channel Angular Pressing

The room temperature microhardness was measured on the samples ECAPed to ¾ = 1­12 and the results are plotted against temperature in Fig. 4(a). The data at 423 K 16) are represented here for reference. Note in Fig. 4 that the hardness at 573 K was examined only in the fi ne-grained regions because of providing compatible data with those obtained at the other deformation temperatures. It is seen in Fig. 4(a) that the microhardness investigated at all ECAP strains monotonically drops in the temperature intervals from 423 to 523 K and from 573 to 723 K; this may be normally related to acceleration of the rate of restoration processes taking place in deformation structures, which is controlled mainly by dynamic recovery. 15) On the other hand, the microhardness is nearly unchanged at the temperatures from 523 to 573 K, at which SRX takes place (Fig. 2). This may suggest an inability of the material to recover rapidly in dislocation substructures developed. Now this will be discussed below in detail.
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Microstructure evolution of AA7050 Al alloy during Equal-Channel Angular Pressing

Microstructure evolution of AA7050 Al alloy during Equal-Channel Angular Pressing

Rockwell B hardness tests were performed on all samples for a preliminary assessment of mechanical properties. Seven measurements were taken from each sample and the average value of five measurements, excluding the highest and lowest values, were recorded. Samples in the initial condition and after one pass of ECAP were subjected to tensile tests. Samples having 4 mm diameter and 25 mm length at the thinner gauge section were tested in a universal testing machine with a crosshead speed of 0.5 mm/min. Three samples of each condition were tested and the average values for yield and ultimate strength, as well as elongation, were recorded. Variance analysis (ANOVA) was used to compare statistical differences among the mean values of hardness and tensile properties of the samples with a confidence interval of 95%.
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Grain refinement of bronze alloy by equal-channel angular pressing (ECAP) and its effect on corrosion behaviour

Grain refinement of bronze alloy by equal-channel angular pressing (ECAP) and its effect on corrosion behaviour

is shown in Fig. 5 . The results reveal that corrosion potential for all samples tends from the moment of immersion towards more negative values. This behaviour represents the breakdown of the pre-immersion air formed an oxide film and dissolution of bronze. After passing a long time of immersion, the potential stabilizes. This represents the formation of the passive film on the surface, which will enhance the free corrosion potential of samples. Furthermore, Fig. 5 indicates that the ECAPed samples need less time to reach the stable OCP values while the as-cast sample seems to need more time to reach the stable OCP value. On the other hand, the results indicate that the corrosion potential shifts to more positive potential with increasing ECAP Fig. 1. Effect of equal-channel angular pressing on microstructure of bronze alloy. (a) 0- pass, (b) 1-pass, (c) 3-passes and (d) 5-passes.
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Microstructure and Mechanical Properties of Cp Al Chips Consolidated Through Hot Equal Channel Angular Pressing

Microstructure and Mechanical Properties of Cp Al Chips Consolidated Through Hot Equal Channel Angular Pressing

Micro structural evolution taking place during equal channel angular pressing (ECAP) was studied in an as- cast 0.16%Zr modified 7475 aluminium alloy at a temperature of 673 K. The structural changes are characterized by development of deformation bands due to large strain in homogeneity occurring through the ECAP die. Repeated deformation leads to an increasing of number and misorientation angle of the boundaries of deformation bands, finally followed by formation of new fine grains at high strains. The misorientation angle distribution for newly developed boundaries shows a single peak type at relatively low misorientations in low strain and changes to a bimodal distribution with two peaks at low and high misorientations in moderate strain. Pressing to a strain of 12 leads to a full development of new grains surrounded by medium to high angle boundaries with an average size of about 1.7 mm. It is concluded that grain refinement occurs by a deformation-induced continuous reaction, that is essentially similar to continuous dynamic recrystallization [6].
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Effect of Equal Channel Angular Pressing (ECAP) on Wear Behavior of Al-7075 Alloy

Effect of Equal Channel Angular Pressing (ECAP) on Wear Behavior of Al-7075 Alloy

undertaken using transmission electron microscopy (TEM) and the surface of worn specimens was investigated by scanning electron microscopy (SEM). The effect of load and ECAP process on the mass loss, have been explained with respect to microstructure and wear mechanism. Comparison of wear resistance of specimens shows that by using ECAP process, wear resistance of the specimens increases considerably due to the formation of very fine grains during ECAP.

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A Review: Plastic Deformation through Equal Channel Angular Pressing

A Review: Plastic Deformation through Equal Channel Angular Pressing

increases and form heterogeneous structure characteristics due to the deformation conditions of the deformed material. The resulting structure influences the mechanical properties of the metal and as such, it is of great interest to understand the origin and evolution of the dislocation structures [3]. Ultrafine grained material has allowed the design and manufacture of aluminium components to require fewer manufacturing steps. ECAP is capable of producing ultrafine grained microstructures in Al alloy and this will practically depend upon the advantages obtained when this process is combined with conventional forming techniques [4]. Deformation is, of course, a continuous process and at any particular point in a deforming body, the state of strain changes from one instant to the next and the sequence of these states of strain are called the strain path, or strain history. The difference between the states of strain at two points in the strain path is called finite strain if however; the interval between the two points is finite. Thus, if the interval is infinitely small, then the strain path is known as an incremental strain. In many engineering tests and manufacturing processes the strain paths are not coaxial [5]. The changes in strain path directions have a significant effect on the mechanical response of metals. The effect of a certain pre-strain becomes manifested by an increase in re- loading yield stress, transient hardening, hardening recovery and failure shift. However, the effect is toughly anisotropic and is dependent on the extent of pre-strain [6]. The improvement in the strength properties of polycrystalline metallic materials with preservation of sufficient toughness can be achieved by refining of grains. Equation (1) shows the Hall-Petch relationship between the grain size and the level of yield strength. This relationship can be used in extensive interval of grain sizes, up to several dozens of nanometres.
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Influence of processing severity during equal-channel angular pressing on the microstructure of an Al-Zn-Mg-Cu alloy

Influence of processing severity during equal-channel angular pressing on the microstructure of an Al-Zn-Mg-Cu alloy

Finally, the hardness exhibited a marked increase from 76 HV in the as-started material to 133 HV in the material subjected to 8 ECAP passes at 130 ºC, and 135 HV after 3 ECAP passes at a lower processing temperature (Table 5). These microhardness values achieved after the most severe processing conditions are very similar, and they are mainly determined by the (sub)grain sizes obtained after both processing paths (Table 3 and 4). On the other hand, the hardness slowly increases with Np, being 120 HV for three passes and 133 HV for eight passes. Previous results [60,79] showed that there is no significant change in the hardness distributions in pure Al after four ECAP passes. However, our results are in agreement with an earlier report on Al–Mg alloys [80], where an increase in the microhardness value was shown up to higher number of ECAP passes, due to the lower rates of recovery in the alloys [43,81]. This slow recovery leads to finer grain sizes in alloys after ECAP processing than in pure Al, being necessary to impose a larger number of passes in order to establish a highly misoriented microstructure [82].
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Microstructure and Texture Evolution of the Al 20Sn Alloy Processed by Equal Channel Angular Pressing Using Route C

Microstructure and Texture Evolution of the Al 20Sn Alloy Processed by Equal Channel Angular Pressing Using Route C

After the ECAP process the micro-strain of the Al-20%Sn alloy considerably increased between 0 and 1 passes, but for the subsequent passes it remained relatively constant. The microstructure evolved from a coarse grain of several microns to a more refined grain size as the ECAP passes progressed. The dislocation cells tended to accommodate in a way that new grain boundaries were formed, giving place to a subgrain array. A mixture of copper and shear {111}©112ª textures evolved with the number of ECAP passes; to confirm this, the ODFs also showed the continues changes between the texture at n = 1 pass and the fi nal texture at n = 5 passes. The overall microhardness increased as a result of the grain size re fi nement. The heterogeneity of the obtained micro- hardness values subsisted even at 5 ECAP passes, being compatible with the heterogeneity of the resulting micro- structure.
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Microstructure and texture evolution of the Al-20sn alloy processed by equal-channel angular pressing using route C

Microstructure and texture evolution of the Al-20sn alloy processed by equal-channel angular pressing using route C

Among the most important internal effects that occur during the ECAP process, the grain refinement and the increase of the micro-strain can be highlighted. As a consequence, the broadening of the XRD peaks is expected. Figure 2(a) shows the plane (311), where the peak broad- ening after the first ECAP pass is observed. It is worth noting that the peak broadening effect at passes from n = 1 to 5 is rather marginal, but the effect on the microstructure, as it will be discussed later, is important. On the other hand, Fig. 2(b) shows the (101) plane for Sn. This clearly demonstrates that the width of the Sn XRD peaks does not depend on the number of ECAP passes, since it recrystallizes at room temperature. As the grain size observed by electron mi- croscopy (Fig. 3) exceeds the 100 nm, which, as mentioned above, is the threshold imposed by the instrumental broad- ening, thus the micro-strain was taken as the dominant effect and the contribution of the grain size was not that significant (in terms of reducing the peak width).
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Influence of equal-channel angular pressing on the microstructure and corrosion behaviour of a 6xxx aluminium alloy for automotive conductors

Influence of equal-channel angular pressing on the microstructure and corrosion behaviour of a 6xxx aluminium alloy for automotive conductors

Fig. 3a shows the relative fraction of HAGBs and LAGBs for each sample. Due to the high elongation of grains in the longitudinal section, it was difficult to determine the density ofboundaries for these sections. Therefore, only restùts for the transverse sections are discussed. Results showed that the relative fraction of HAGBs was increased by 80 % and 147 % for ECAP-RR and ECAP-RH samples, respectively. Those results were consistent with previous conclusions, i.e. a decrease in the grain size with ECAP and a smaller average grain size for ECAP-RH samples. Indeed, as stated in the literature, grain refinement during ECAP was commonly linked to the formation of HAGBs due to recrystallisation processes [15,28,45]. To confirm these restùts and avoid the problems due to the identification of grains, the total length of boundaries was calculated for each sample (Fig. 3b). An increase in the total length of boundaries was observed after ECAP, in particular after ECAP-RH. Furthermore, for ECAP-RR and ECAP-RH samples, the length of both HABGs and LAGBs increased compared to the as-received sample, with a very strong increase in the total length of HAGBs for ECAP-RH sample. Those restùts clearly showed that the increase of processing temperature during ECAP-RH enabled a homogeneous recrystallisation phenomenon leading to small recrystallised grains; the temperature was not high enough to lead to a coarsening of the recrystallised grains. After ECAP-RR, because of the lower temperature during the de­ formation process, a more heterogeneous microstructure was obtained due to an incomplete recrystallisation process; it combined large and small grains, the smallest ones being formed either by a recrystallisation process or by the subdivision of larger grains during deformation. 3.1.2. Texture analysis
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Microstructure Evaluation of Equal Channel Angular Extrusion in Aluminium 5083 Alloy by Cryogenic Treatment

Microstructure Evaluation of Equal Channel Angular Extrusion in Aluminium 5083 Alloy by Cryogenic Treatment

commercially available aluminium magnesium (Al 5083) alloy with equal channel angular extrusion process (ECAP) using route-Bc at room temperature and cryogenic conditions. Initially before the ECAP process the material properties were tabulated. And subsequently the properties of the material after the ECAP process is tabulated against the initial properties of the material, And along with the two readings the properties of material which undergone cryogenic treatment is tabulated. In this study it was clear that the mechanical properties of the material in cryogenic conditions are found to be better than the other two readings. With the increase in pass number the micro hardness and tensile strength of the alloy increases. The tested alloy can be used in various engineering applications requiring high strength.
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Shape memory effect of NiTi alloy processed by equal-channel angular pressing followed by post deformation annealing

Shape memory effect of NiTi alloy processed by equal-channel angular pressing followed by post deformation annealing

Post-deformation annealing (PDA) after one-pass ECAP processing was performed at 400 °C for various times (5-300 min) in a vacuum furnace. It has been reported that the best superelasticity and shape memory characteristics are obtained, when the specimen is annealed at 400 °C immediately after cold-working [2]. Microhardness measurements were taken at the centers of the longitudinal sections of the billets parallel to the pressing direction (X direction). A load of 100 gf was applied for 10 s. At every point the local value of Hv was taken as the average of five separate hardness values.To study the phases, X-ray diffraction (XRD) was used in employing Cu Kα radiation at 40 kV and tube current of 30 mA. The XRD measurements were carried out over the 2θ range from 30° to 50°, using a step size of 0.02° with a counting time of 9.6 s at each step. The stress-strain curves were recorded for a study of the shape memory effect by miniature tensile specimen with 2 mm gage length using a Santam universal testing machine with a load capacity of 2 kN and the cross-head speed was set at 0.1 mm.min -1 , equivalent to a strain rate of ~7.4 × 10 -4 s -1 . The strain recovery of the specimens was measured after loading to 6 and 8 pct strain followed by unloading and heating up to ~150 °C by dipping in hot oil followed by ice-water quenching.
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Effect Of Equal Channel Angular Pressing On Microstructure And Mechanical Properties On Non Dendritic LM25 Aluminium Alloy

Effect Of Equal Channel Angular Pressing On Microstructure And Mechanical Properties On Non Dendritic LM25 Aluminium Alloy

5.1 Variation of Comparison of Ultimate Tensile Strength of As-cast, non-heat treated CS, T6 heat treated CS, non-heat treated ECAP and T6 heat treated ECAP 49 5.2 The elongation to fracture of each type of LM25 alloy sample 50 5.3 SEM image for fracture testing in as-cast sample 51 5.4 SEM image for fracture testing in non-heat treated CS sample 51 5.5 SEM image for fracture testing in heat treated CS sample 52 5.6 SEM image for fracture testing in non-heat treated ECAP sample 52 5.7 SEM image for fracture testing in T6 heat treated ECAP sample
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