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Sung Hyuk Park - One of the best experts on this subject based on the ideXlab platform.
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effects of Extrusion Speed on the microstructure and mechanical properties of mg 9al 0 8zn 0 9ca 0 6y 0 5mm alloy
Metals and Materials International, 2021Co-Authors: Dong Hee Lee, Youngmin Kim, Sanghoon Kim, Hyun Ji Kim, Byoung Gi Moon, Sung Hyuk ParkAbstract:The effects of Extrusion Speed on the microstructure and tensile properties of a recently developed Mg–9Al–0.8Zn–0.9Ca–0.6Y–0.5MM (AZXWMM91100) alloy are investigated by extruding at various ram Speeds of 1, 4, 7, 10, and 13 mm/s. Direct Extrusion results reveal that numerous small edge cracks form in the sheets extruded at ram Speeds between 4 and 10 mm/s, whereas severe hot cracking occurs during Extrusion at 13 mm/s. All extruded sheets show a fully recrystallized grain structure containing second-phase particles aligned along the Extrusion direction. The average size of the recrystallized grains gradually increases with the increasing ram Speed, because a higher Extrusion Speed generates more deformation heat. However, the size, morphology, amount, and distribution of the second-phase particles are nearly identical in all the extruded sheets. As the ram Speed increases from 1 to 10 mm/s, the tensile yield strength of the extruded material decreases from 205 to 125 MPa, which is attributed to the decrease in the grain-boundary hardening effect caused by the grain coarsening. The tensile elongation increases from 13.0% at 1 mm/s to 15.1% at 4 mm/s, and then greatly decreases to 2.9% at 10 mm/s. The drastic ductility degradation of the sheets extruded at the ram Speeds larger than 7 mm/s is due to the formation of relatively coarse internal cracks in the material during Extrusion.
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high Speed indirect Extrusion of mg sn al zn alloy and its influence on microstructure and mechanical properties
Journal of Alloys and Compounds, 2016Co-Authors: Sung Hyuk Park, Jonghun YoonAbstract:Abstract This investigation into the effect of indirectly extruding Mg–7Sn–1Al–1Zn (TAZ711) alloy at high exit Speeds on the microstructure and tensile properties found no evidence of surface cracking, not even at the maximum Speed tested of 27 m/min. This high-Speed extrudability is attributed to the relatively high incipient melting temperature of the alloy (535 °C), which results from the formation of a thermally stable Mg 2 Sn phase. All extruded samples exhibited a completely recrystallized (DRXed) structure consisting of coarse DRXed grains with few particles in combination with relatively fine DRXed grains containing numerous fine precipitates. With an increase in Extrusion Speed, the total amount of Mg 2 Sn precipitates decreased and the size and quantity of coarse DRXed grains increased due to a rise in temperature during Extrusion. This has the effect of reducing the strength of the extruded alloy through a reduction in precipitation and grain-boundary strengthening, yet the elongation of the extruded alloy remains essentially the same due to a loss of ductility caused by the increase in DRXed grain size.
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effects of Extrusion Speed on the microstructure and mechanical properties of zk60 alloys with and without 1 wt cerium addition
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: Sung Hyuk Park, Bong Sun You, Youngmin Kim, Sung Soo ParkAbstract:Abstract The effects of Extrusion Speed on the microstructure and tensile properties of the ZK60 and ZK60-1Ce alloys were investigated by performing indirect Extrusion at three ram Speeds (0.3, 1.0 and 3.0 mm/s). All of the extruded alloys showed a bimodal microstructure consisting of equiaxed fine recrystallized (DRXed) grains and elongated coarse unDRXed grains. With increasing Extrusion Speed, the exit temperature increased due to deformation heating, resulting in a larger grain and a higher DRXed fraction. The yield and ultimate tensile strengths and elongation at RT decreased with an increase of Extrusion Speed. The ZK60-1Ce alloys exhibited a finer grain size, a higher DRXed fraction, and weaker texture intensity than the ZK60 alloys at the same Extrusion Speed due to the inhibition of grain growth by the pinning effect and the promotion of DRX by particle-stimulated nucleation. The yield and ultimate tensile strengths at room and elevated temperatures were increased by the addition of Ce, while elongation was decreased due to cracking at the Mg–Zn–Ce particles.
Guoqun Zhao - One of the best experts on this subject based on the ideXlab platform.
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effects of Extrusion parameters and post heat treatments on microstructures and mechanical properties of Extrusion weld seams in 2195 al li alloy profiles
Journal of materials research and technology, 2020Co-Authors: Guoqun Zhao, Yongxiao Wang, Xiaoxue Chen, Wendong ZhangAbstract:Abstract To obtain profiles with sound weld seams, the effects of Extrusion parameters and heat treatment on microstructures and mechanical properties of the weld seam were revealed. It was found that the high Extrusion Speed increases the mechanical properties and welding quality of the welding area. The micro-voids formed in low temperature and low Extrusion Speed could hinder the grains from growing through the welding interface during heat treatment, which caused weak bonding of the weld seam. Lots of strengthening phases precipitated during aging treatment, which leads to the disappearance of the softened welding area and the improvement of tensile strength. However, the fine grains of welding area translated to coarse grains quickly during solution treatment, and the precipitated phases coarsened and the precipitation free zone (PFZ) widened when the aging time is excessive, above reasons result in the layered fracture of welding area and poor elongation. Tensile strength and elongation were improved simultaneously because of the fine grain boundary precipitates, narrow PFZ and fine homogeneous T1 phases formed in under-aged (UA) treatment. The weld seam obtained by high Extrusion Speed shows a fine combination of ultimate tensile strength (UTS) and elongation after UA treatment.
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effect of Extrusion Speeds on the microstructure texture and mechanical properties of high Speed extrudable mg zn sn mn ca alloy
Vacuum, 2018Co-Authors: Guoqun Zhao, Cunsheng Zhang, Jixue Zhou, Lu SunAbstract:Abstract A new type of low-cost Mg-3.36Zn-1.06Sn-0.33Mn-0.27Ca (wt.%) (named as ZTMX3100) alloy ingot with good extrudability was prepared by semi-continuous casting. Two-stage homogenization treatment and hot Extrusion were performed on the ingot. The effects of Extrusion Speeds (0.2–10 mm/s) on the extrudability, microstructure and mechanical properties of the alloy were investigated. The excellent extrudability of the alloy is attributed to the high incipient melting temperature of 572 °C resulting from the formation of thermally stable phase CaMgSn. CaMgSn phases distribute along the Extrusion direction at each Extrusion Speed. The average grain size increases gradually and distribution uniformity of grain size firstly increases and then decreases. The as-extruded alloys exhibit textures with (0001) basal planes parallel to Extrusion direction. Besides, the alloy exhibits a 1 ¯ 0> or 1 ¯ 0> − 2 ¯ 0> fiber texture depending on Extrusion Speed. The alloy extruded at 0.2 mm/s presents the highest mechanical property, which is attributed to the fine grain structure, strengthening effect from second phase particles, and weak basal texture. The alloy extruded at high Speed of 10 mm/s (die-exit Speed 18 m/min) still maintains a relatively high strength and elongation, which is mainly due to the combined effect of moderate alloying content and thermally stable phase CaMgSn.
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interfacial structure and bonding mechanism of weld seams during porthole die Extrusion of aluminum alloy profiles
Materials Characterization, 2018Co-Authors: Guoqun ZhaoAbstract:Abstract Fine nanostructures of bonding interfaces of weld seams formed by porthole die Extrusion in the absence/presence of a gas-pocket behind the bridge of the Extrusion die were systematically studied to understand the underlying interfacial bonding mechanisms. Interfacial grain boundaries, nanoscale amorphous layers, and three kinds of new interfacial structures were found. Specifically, it was found that, in the absence of a gas-pocket behind the bridge, there are two distinctly different interfacial structures. For the first kind of bonding interface, interfacial grain boundaries exist in contact areas and micro-voids exist in non-contact areas. For the second kind of bonding interface, there are no interfacial grain boundaries in contact areas and only nanoscale micro-voids exist in non-contact areas. In the presence of a gas-pocket behind the bridge, nanoscale voids and amorphous layers exist at the bonding interface. It was also found that the formation of gas-pockets can be avoided by increasing the depth of the welding chamber, and the increase of the welding chamber's depth and Extrusion Speed also contributes to the volume reduction of micro-voids and the migration of grain boundaries at the bonding interface, so as to improve the welding quality of weld seams. Based on the experimental findings, two interfacial bonding mechanisms corresponding to the absence/presence of a gas-pocket are proposed. The specific behavior of micro-asperities contact, micro-voids closure, oxide films breaking and interfacial grain boundaries migration are described, and the solid-state bonding process during porthole die Extrusion is revealed from the micro-nano scales.
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microstructural evolution and mechanical properties of welding seams in aluminum alloy profiles extruded by a porthole die under different billet heating temperatures and Extrusion Speeds
Journal of Materials Processing Technology, 2017Co-Authors: Guoqun Zhao, Weichao Cui, Cunsheng Zhang, Liang ChenAbstract:Abstract Porthole die Extrusion process of aluminum alloy profiles is a hot deformation process involving solid state welding. Microstructural evolution of welding seams is the key factor to determine mechanical properties of extruded profiles. In this work, the grain structure, bonding interface structure and precipitates of welding seams in the profiles extruded under different billet heating temperatures and Extrusion Speeds were characterized, and the hardness, strength and ductility of welding seams were analyzed. The influence of billet heating temperature and Extrusion Speed on the microstructure and mechanical properties of welding seams was studied. It was found that, in the porthole die Extrusion process of aluminum alloy profiles, fine or coarse grains and micro-voids can be formed in welding seams. Although the new grains through the bonding interface have been formed, there are still many micro-voids in these new grains. Increasing billet heating temperature and Extrusion Speed not only contributes to the formation of the new grains through the bonding interface, but also promotes the closure of the micro-voids on the bonding interface, and thereby improves the atomic bonding degree of the material on both sides of the bonding interface. The hardness, strength and ductility of the extruded profiles can be improved by increasing billet heating temperature and Extrusion Speed.
D.i. Wilson - One of the best experts on this subject based on the ideXlab platform.
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modelling of paste ram Extrusion subject to liquid phase migration and wall friction
Chemical Engineering Science, 2017Co-Authors: M J Patel, S Blackburn, D.i. WilsonAbstract:Abstract Extrusion of solid-liquid particulate pastes is a well-established process in industry for continuously forming products of defined cross-sectional shape. At low Extrusion velocities, the solids and liquid phases can separate due to drainage of liquid through the interparticle pores, termed liquid phase migration (LPM). The effect of wall friction, die shape and Extrusion Speed on LPM in a cylindrically axisymmetric ram extruder is investigated using a two-dimensional finite element model of paste Extrusion based on soil mechanics principles (modified Cam-Clay). This extends the smooth walled model reported by Patel et al. (2007) to incorporate a simplified Tresca wall friction condition. Three die entry angles (90°, 60° and 45°) and two Extrusion Speeds are considered. The Extrusion pressure is predicted to increase with the Tresca friction factor and the extent of LPM is predicted to increase with decreasing ram Speed (both as expected). The effects of wall friction on LPM are shown to be dictated by the die shape and ram displacement: there are few general rules relating extruder design and operating conditions to extent of LPM, so that finite element-based simulation is likely to be needed to predict the onset of LPM accurately.
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Optimization of a high strenght mesalamine multi-particulate dosage form
Tipolitografia Manfredi Varese, 2011Co-Authors: G. Di Pretoro, Lucia Zema, S L Rough, D.i. Wilson, L. Palugan, Andrea GazzanigaAbstract:Background: 5-aminosalicylic acid (5-ASA, mesalamine) is at present the treatment of choice for Inflammatory Bowel Diseases (IBD), with a therapeutic regimen of 2.4-4.8 g/day. However, most of the mesalamine-based products currently available on the market contain a dose of 5-ASA (generally 500 mg API/unit) which is relatively low if considering the aforementioned dosage regimen. A high strength dosage form containing more than 1 g 5-ASA would therefore be of interest to reduce daily administrations and hence improving compliance. Multi-particulates dosage forms, based on high density pellets, have been sought as promising alternatives for the administration of 5-ASA, both for their biopharmaceutical (e.g. more even and predictable distribution and transportation in the gastro-intestinal tract) and technological (e.g. high drug loading and ease of drug release modulation) advantages. In a previous study (Di Pretoro et al., 2010) a lab-scale ram extruder was employed to investigate the influence of 5-ASA chemical (acidity) and physical (particle size and shape) characteristics on the rheological behaviour of highly-drug loaded pastes. A formulation route for the development of a 90 wt% 5-ASA/microcrystalline cellulose wet mass based on milled 5-ASA, which gave good yields of pellets at the lab scale, was successfully identified. Purpose: To improve further the promising formulation identified at the lab scale and to assess the feasibility of scaling up to a pilot plant apparatus (basket extruder) using a mixed fractional factorial approach. In addition, an optimisation study, aiming to identify the optimal formulation and process parameters for the development of a high strength multi-particulate dosage form at the pilot scale, was performed. Methods: A Nica\uae pilot-scale extruder (basket type), coupled with a cross-hatched friction plate spheroniser, was used for pellet preparation. Colloidal microcrystalline cellulose (Avicel RC591) was chosen as E-S aid. The primary liquid binder was water, with polyvinylpyrrolidone (PVP) used as extra binder. A 3x24-1 fractional factorial design was employed to investigate the effects of three formulation components (5-ASA loading, PVP content and water amount in paste formulation) and two process parameters (Extrusion Speed and spheronisation time) on process yield and on the final properties of the pellets, namely size, shape, mechanical resistance, bulk density and dissolution properties. 27 runs, including 3 replicates of the central point, were performed. An optimisation process was also carried out, using the desirability function. Results: The 5-ASA loading, PVP content and water amount had a significant effect (p
Jonghun Yoon - One of the best experts on this subject based on the ideXlab platform.
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high Speed indirect Extrusion of mg sn al zn alloy and its influence on microstructure and mechanical properties
Journal of Alloys and Compounds, 2016Co-Authors: Sung Hyuk Park, Jonghun YoonAbstract:Abstract This investigation into the effect of indirectly extruding Mg–7Sn–1Al–1Zn (TAZ711) alloy at high exit Speeds on the microstructure and tensile properties found no evidence of surface cracking, not even at the maximum Speed tested of 27 m/min. This high-Speed extrudability is attributed to the relatively high incipient melting temperature of the alloy (535 °C), which results from the formation of a thermally stable Mg 2 Sn phase. All extruded samples exhibited a completely recrystallized (DRXed) structure consisting of coarse DRXed grains with few particles in combination with relatively fine DRXed grains containing numerous fine precipitates. With an increase in Extrusion Speed, the total amount of Mg 2 Sn precipitates decreased and the size and quantity of coarse DRXed grains increased due to a rise in temperature during Extrusion. This has the effect of reducing the strength of the extruded alloy through a reduction in precipitation and grain-boundary strengthening, yet the elongation of the extruded alloy remains essentially the same due to a loss of ductility caused by the increase in DRXed grain size.
Su Hai Hsiang - One of the best experts on this subject based on the ideXlab platform.
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investigation of the influence of process parameters on hot Extrusion of magnesium alloy tubes
Journal of Materials Processing Technology, 2007Co-Authors: Su Hai HsiangAbstract:Abstract During the hot Extrusion of magnesium alloy, the change of process parameters will affect the mechanical properties of extruded products. In this study, Taguchi method and analysis of variance (ANOVA) are applied to analyze the influence of process parameters on the hot Extrusion of magnesium alloy tubes under Extrusion ratio of 21.05. The experiments are arranged by orthogonal array method in which magnesium alloys AZ31and AZ61 are used as outer arrays, the factors selected as inner arrays are the billet heating temperature, the initial Extrusion Speed, the container temperature and the lubricants. The extruded tubes will be carried out tensile test and flattening test, the test results are analyzed by the quality measurement of Taguchi method to find the relationship between the process parameters and mechanical properties of the products, and to acquire the optimal combination of parameters. Then based on the results obtained from the additive model, confirmatory experiments are performed. Besides, the microstructures of extruded tubes are observed to clarify the influence of process parameters on the grain size. Finally, with the same Extrusion condition, the variations in tensile strength and flattening strength due to different compositions are discussed.
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an investigation on the hot Extrusion process of magnesium alloy sheet
Journal of Materials Processing Technology, 2003Co-Authors: Su Hai HsiangAbstract:Abstract This study investigates the hot Extrusion of magnesium alloy sheets at various temperatures, material, Speed and lubricant. A multi-Speed method is applied to extrude a magnesium alloy sheet at a high Extrusion ratio. The experimental results are analyzed to optimize the processing conditions, increase the tensile strength and reduce the Extrusion load on the magnesium alloy thin sheet. Nowadays, most magnesium alloy products are manufactured by industrial die casting. Hot Extrusion is seldom used to finish magnesium products because the Extrusion Speed, temperature and Extrusion load significantly effect the properties of the product. In this study, the Taguchi experimental method with the orthogonal array is applied. ANOVA is used to investigate how parameters affect the Extrusion process. All possible mechanical properties of the product are analyzed to obtain the optimal process parameters. In addition, magnesium alloys with different compositions are experimentally tested to determine the mechanical properties of the extruded product and obtain the relationship between the process parameters and the properties of the material.
