Abstract:This paper aimed to propose a novel bulk plastic deformation method entitled hydrostatic backward extrusion process that is an implementation of the benefits of hydrostatic extrusion to the backward extrusion process. The applicability of the process was investigated using experimental tests and finite element analysis. The results showed that the produced tube by hydrostatic backward extrusion exhibits higher effective plastic strain while needing lower process load (elimination of friction force). The maximu… Show more
“…The method was applied to commercial Al and significant grain refinement and improvement in strength were obtained by Hosseini et al . 77 A hydrostatic-based process called ‘hydrostatic back extrusion’, presented by Manafi et al ., 125 may be more suitable for processing hard-to-deform and brittle materials. 126–128 17 Schematic of the new backward extrusion process 78 …”
Section: Spd Processes Suitable For Tubular Samplesmentioning
Severe plastic deformation (SPD) is known to be the best method for producing bulk ultrafine-grained and nanostructured materials with excellent properties. Different SPD methods were developed that are suitable for sheet and bulk solid materials. During the past decade, efforts have been made to create effective SPD processes suitable for producing cylindrical tubes. In this paper, we review SPD processes intended to produce ultrafine-grained and nanostructured tubes, and their effects on material properties. The paper will focus on introduction of the tube SPD processes, and then comparison of them based on their advantages and disadvantages from the viewpoints of processing and properties.
“…The method was applied to commercial Al and significant grain refinement and improvement in strength were obtained by Hosseini et al . 77 A hydrostatic-based process called ‘hydrostatic back extrusion’, presented by Manafi et al ., 125 may be more suitable for processing hard-to-deform and brittle materials. 126–128 17 Schematic of the new backward extrusion process 78 …”
Section: Spd Processes Suitable For Tubular Samplesmentioning
Severe plastic deformation (SPD) is known to be the best method for producing bulk ultrafine-grained and nanostructured materials with excellent properties. Different SPD methods were developed that are suitable for sheet and bulk solid materials. During the past decade, efforts have been made to create effective SPD processes suitable for producing cylindrical tubes. In this paper, we review SPD processes intended to produce ultrafine-grained and nanostructured tubes, and their effects on material properties. The paper will focus on introduction of the tube SPD processes, and then comparison of them based on their advantages and disadvantages from the viewpoints of processing and properties.
“…Peng et al [12], by calculating the stress distribution in Nb/Cu composited by HE, investigated its interface bonding status. Manifi et al [13] improved conventional backward extrusion by employing HE principles to reduce the extrusion load; the maximum load was reduced by 80% compared to the conventional back extrusion process. Kopp and Barton [14] improved the model of HE and analyzed the differences between experimentation and simulation.…”
Section: Fem Methods and Materialsmentioning
confidence: 99%
“…Kopp and Barton [14] improved the model of HE and analyzed the differences between experimentation and simulation. The comparisons between the simulation and experiment were discussed in [10][11][12][13][14], but the comparison between the different simulation models has not been discussed in detail yet. In the present study, the pressure-load mode and displacement-load mode are used to simulate the HE process.…”
Abstract:Two finite element analysis (FEA) models simulating hydrostatic extrusion (HE) are designed, one for the case under pressure load and another for the case under displacement load. Comparison is made of the equivalent stress distribution, stress state ratio distribution and extrusion pressure between the two models, which work at the same extrusion ratio (R) and the same die angle (2α). A uniform Von-Mises equivalent stress gradient distribution and stress state ratio gradient distribution are observed in the pressure-load model. A linear relationship is found between the extrusion pressure (P) and the logarithm of the extrusion ratio (lnR), and a parabolic relationship between P and 2α, in both models. The P-value under pressure load is smaller than that under displacement load, though at the same R and α, and the difference between the two pressures becomes larger as R and α grow.
“…Finite element (FE) simulation by Shatermashhadi et al [10] showed well that the obtained effective strain of the new method was more than twice that of the conventional BE method. Furthermore, Manafi et al [11] introduced hydrostatic pressure in the ACAE to further increase the effective plastic strain and reduce the force load. Also, the feasibility of the process has been verified by the production of pure Al test part [12], and the extruded part achieved evident grain refinement in comparison with the initial material.…”
Microstructure evolution and mechanical properties of AZ80 Mg alloy during annular channel angular extrusion (350 °C) and heat treatment with varying parameters were investigated, respectively. The results showed that dynamic recrystallization of Mg grains was developed and the dendritic eutectic β-Mg17Al12 phases formed during the solidification were broken into small β-phase particles after hot extrusion. Moreover, a weak texture with two dominant peaks formed owing to the significant grain refinement and the enhanced activation of pyramidal <c + a> slip at relative high temperature. The tension tests showed that both the yield strength and ultimate tensile strength of the extruded alloy were dramatically improved owing to the joint strengthening effect of fine grain and β-phase particles as compared with the homogenized sample. The solution treatment achieved the good plasticity of the alloy resulting from the dissolution of β-phases and the development of more equiaxed grains, while the direct-aging process led to poor alloy elongation as a result of residual eutectic β-phases. After solution and aging treatment, simultaneous bonding strength and plasticity of the alloy were achieved, as a consequence of dissolution of coarse eutectic β-phases and heterogeneous precipitation of a large quantity of newly formed β-phases with both the morphologies of continuous and discontinuous precipitates.
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