An experimental study on optimum lubrication for large-scale severe plastic deformation of aluminum-based alloys

Frint, Philipp; Wagner, Martin F.‐X.; Weber, Simon; Seipp, S.; Frint, S.; Lampke, Thomas

doi:10.1016/j.jmatprotec.2016.08.032

Cited by 34 publications

(12 citation statements)

References 17 publications

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“…[16] For lubrication, a commercially available, oil-based grease, containing a mixture of graphite, and molybdenum disulfide (Unimoly RAP) was applied on the billets' surfaces. [17] In this study, only one pass of ECAP (120 die) is investigated due to the material's poor formability which in case of Al-Cu alloys often results in macroscopic failure at low temperatures. [18][19][20] The microstructure of the initial material AA2017 is shown in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

Effect of Creep and Aging on the Precipitation Kinetics of an Al–Cu Alloy after One Pass of ECAP

et al. 2017

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Recent work shows that severe plastic deformation processes such as ECAP or HPT considerably accelerate the precipitation kinetics of Al-Cu alloys. In this study, the authors analyze how a combination of mechanical load, aging time (and increased plastic strain), and aging temperature affects the precipitation kinetics of an AA2017 alloy after ECAP. After solution annealing, the material is processed by one pass of ECAP (120 -channel angle) at 140 C. Compressive creep tests are performed on the initial condition and the ECAP-deformed material. The resulting microstructures are studied in detail using electron microscopy. To investigate the influence of mechanical loading, interrupted compressive creep tests are performed and compared with aged samples (produced without any mechanical loading at the same temperature and after the same amount of time). By keeping time and load constant in another set of interrupted compressive creep tests, the influence of temperature is investigated. Our study shows that increasing mechanical loading further accelerates the precipitation kinetics. Temperature accelerates the precipitation kinetics as well, but results in coarser precipitates. The authors also find that different creep strains can lead to the formation of two different regions in the microstructure: regions with only a few coarsened uphase precipitates, and regions with numerous, finely dispersed precipitates.

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Section: Methodsmentioning

confidence: 99%

Effect of Creep and Aging on the Precipitation Kinetics of an Al–Cu Alloy after One Pass of ECAP

et al. 2017

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“…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. The initial diameter of the billets was 16 mm and the minimum diameter of the concave forming elements was 13 mm.…”

Section: Methodsmentioning

confidence: 99%

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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“…To prevent an excessive temperature increase related to friction and quasi-adiabatic heating, extrusion was carried out at a low ram speed of 18 mm/min. In addition, Bechem Beruforge 150D, a lubricant that is well suited for cold forming of aluminum [16], was applied to the contact areas between the billets and the die. For AT-extrusion, the billets were heated to 170 • C in an induction furnace, while the die was heated in a convection furnace prior to processing.…”

Section: Methodsmentioning

confidence: 99%

Influence of Extrusion Temperature on the Aging Behavior and Mechanical Properties of an AA6060 Aluminum Alloy

Berndt

Frint

Wagner

2018

Metals

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Processing of AA6060 aluminum alloys for semi-products usually includes hot extrusion with subsequent artificial aging for several hours. Processing below the recrystallization temperature allows for an increased strength at a significantly reduced annealing time by combining strain hardening and precipitation hardening. In this study, we investigate the potential of cold and warm extrusion as alternative processing routes for high strength aluminum semi-products. Cast billets of the age hardening aluminum alloy AA6060 were solution annealed and then extruded at room temperature, 120 or 170 • C, followed by an aging treatment. Electron microscopy and mechanical testing were performed on the as-extruded as well as the annealed materials to characterize the resulting microstructural features and mechanical properties. All of the extruded profiles exhibit similar, strongly graded microstructures. The strain gradients and the varying extrusion temperatures lead to different stages of dynamic precipitation in the as-extruded materials, which significantly alter the subsequent aging behavior and mechanical properties. The experimental results demonstrate that extrusion below recrystallization temperature allows for high strength at a massively reduced aging time due to dynamic precipitation and/or accelerated precipitation kinetics. The highest strength and ductility were achieved by extrusion at 120 • C and subsequent short-time aging.

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An experimental study on optimum lubrication for large-scale severe plastic deformation of aluminum-based alloys

Cited by 34 publications

References 17 publications

Effect of Creep and Aging on the Precipitation Kinetics of an Al–Cu Alloy after One Pass of ECAP

Effect of Creep and Aging on the Precipitation Kinetics of an Al–Cu Alloy after One Pass of ECAP

Microstructural Evolution during Severe Plastic Deformation by Gradation Extrusion

Influence of Extrusion Temperature on the Aging Behavior and Mechanical Properties of an AA6060 Aluminum Alloy

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