Influence of die geometry on performance in gradation extrusion using numerical simulation and analytical calculation

Landgrebe, Dirk; Sterzing, Andreas; Schubert, Nadine; Bergmann, Markus

doi:10.1016/j.cirp.2016.04.128

Cited by 7 publications

(13 citation statements)

References 5 publications

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“…The process basically fulfills the requirements for severe plastic deformation processes (SPD processes) since large effective strains, load path changes, high hydrostatic pressure, and temperatures below recrystallization temperature are applied. These results show that processing by gradation extrusion has a high potential for grain refinement by SPD, which leads to the assumption that distinct microstructural gradients may occur [28]. For a detailed analysis of the microstructure discussed below, five distinct locations are highlighted in Figure 3, representing interesting stages of deformation history during processing.…”

Section: Methodsmentioning

confidence: 99%

“…Both tool parts (punch and die) were defined as rigid bodies. The material and friction description used for the numerical simulation are summarized in Table 2 [28], where ϕ corresponds to true strain. Table 2.…”

Section: Methodsmentioning

confidence: 99%

“…Note that the pressing speed is a major processing factor that influences several aspects of the forming process like temperature gradients and failure mechanisms. Further details on the influence of pressing speed in conjunction with other parameters such as die geometry are discussed elsewhere [28]. In order to reduce friction during the gradation extrusion experiments, a commercial lubricant spray containing molybdenum disulfide and graphite that is commonly used for SPD processes [31] was applied on the cavity surface.…”

Section: Methodsmentioning

confidence: 99%

“…Another important requirement for effective grain refinement is a large induced equivalent strain. The gradation extrusion principle is therefore characterized by a stepwise generation of local plastic strain at the forming elements which is accumulated during the deformation path through the corresponding tool [28,29]. This approach has a certain potential to produce an ultrafine-grained microstructure which can extend up to a depth of several millimeters from the billet's surface.…”

Section: Introductionmentioning

confidence: 99%

“…In the present work, a distinct microstructural gradient is created by a heterogeneous introduction of severe plastic deformation. Based on the principle of direct extrusion processing, a novel approach of gradation extrusion has recently been developed [27,28]. This bulk forming method is basically a type of direct impact extrusion that has also been registered for patent [29].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Microstructural Evolution during Severe Plastic Deformation by Gradation Extrusion

Frint

Härtel

Selbmann

et al. 2018

Metals

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Abstract:In this contribution, we study the microstructural evolution of an age-hardenable AA6082 aluminum alloy during severe plastic deformation by gradation extrusion. A novel die design allowing an interruption of processing and nondestructive billet removal was developed. A systematic study on the microstructure gradient at different points of a single billet could be performed with the help of this die. Distinct gradients were investigated using microhardness measurements and electron microscopy. Our results highlight that gradation extrusion is a powerful method to produce graded materials with partially ultrafine-grained microstructures. From the point of view of obtaining an ultrafine-grained surface layer with maximum hardness, only a small number of forming elements is needed. It was also found that large incremental deformation by too many forming elements may result in locally heterogeneous microstructures and failure near the billet surface caused by localization of deformation. Furthermore, considering economical aspects of processing, fewer forming elements are preferred since several processing parameter-related cost factors are then significantly lower.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Microstructural Evolution during Severe Plastic Deformation by Gradation Extrusion

Frint

Härtel

Selbmann

et al. 2018

Metals

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An overview on severe plastic deformation: research status, techniques classification, microstructure evolution, and applications

Bagherpour

Pardis

Reihanian

et al. 2018

Int J Adv Manuf Technol

120

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The present overview gives a new approach toward developments and recent achievements in severe plastic deformation. The review focuses on several subjects. First, an outline of SPD research status in the world is presented by literature analysis based on the total number of publications, citations and the contribution of the topranked countries. Second, the mechanisms of grain refinement and grain growth during SPD processing are discussed by means of the latest concepts. Third, all SPD methods invented so far are classified based on a new approach. Up to now, the growing tendency of researchers to introduce new SPD techniques results in a large number of SPD methods which can be considered as new or modified techniques or a combination of previous ones. Such a reference can help to prevent the future duplication to introduce the SPD processes, which are technically similar. At the end, the practical applications of ultrafine/nanostructured materials and industrial commercialization of SPD methods are summarized.

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Concept for controlled adjustment of residual stress states in semi-finished products by gradation extrusion

et al. 2021

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The residual stress distribution in extruded components and wires after a conventional forming process is frequently unfavourable for subsequent processes, such as bending operations. High tensile residual stresses typically occur near the surface of the wire and thus limit further processability of the material. Additional heat treatment operations or shot peening are often inserted to influence the residual stress distribution in the material after conventional manufacturing. This is time and energy consuming. The research presented in this paper contains an approach to influence the residual stress distribution by modifying the forming process for wire-like applications. The aim of this process is to lower the resulting tensile stress levels near the surface or even to generate compressive stresses. To achieve these residual compressive stresses, special forming elements are integrated in the dies. These modifications in the forming zone have a significant influence on process properties, such as degree of deformation and deformation direction, but typically have no influence on the diameter of the product geometry. In the present paper, the theoretical approach is described, as well as the model set-up, the FE-simulation and the results of the experimental tests. The characterization of the residual stress states in the specimen was carried out by X-ray diffraction using the sin2Ψ method.

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Influence of die geometry on performance in gradation extrusion using numerical simulation and analytical calculation

Cited by 7 publications

References 5 publications

Microstructural Evolution during Severe Plastic Deformation by Gradation Extrusion

Microstructural Evolution during Severe Plastic Deformation by Gradation Extrusion

An overview on severe plastic deformation: research status, techniques classification, microstructure evolution, and applications

Concept for controlled adjustment of residual stress states in semi-finished products by gradation extrusion

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