Papers by Keyword: Semi-Solid Slurry

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Authors: Jun Xu, Zhi Hua Gao, Zhi Feng Zhang, Men Gou Tang, Wei Dong Yu
Abstract: Annular electromagnetic stirring (A-EMS) process is verified an advanced metal melt treatment technology. Application research was performed to investigate the solidification behavior of Al-Zn-Mg-Cu alloy in this study. The results indicated that uniformly fine microstructure, less composition macro-segregation and improved mechanical properties were achieved.
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Authors: Jessada Wannasin
Abstract: A rheocasting technique called the Gas Induced Semi-Solid (GISS) is being developed for commercial applications in Thailand. The process creates semi-solid metal slurries by applying the injection of fine inert gas bubbles through a graphite diffuser to induce localized convection and heat extraction. The slurries are then formed into parts using different casting processes such as die casting, squeeze casting, gravity casting, and semi-solid infiltration process. This paper reports some of the current applications of the GISS forming processes, including prosthetic adaptors, lapping plates, sacrificial anodes, and armor plates. Preparation of semi-solid slurries of the alloys used in these applications, which are aluminum 356, Sn-Sb, Al-Zn-In, and 7075 alloys, is also reported and discussed.
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Authors: Shu Sen Wu, Jun Wen Zhao, Li Ping Zhang, Ping An, You Wu Mao
Abstract: The effect of processing parameters on the semi-solid microstructure has been investigated in the course of semi-solid slurry preparation of A356 Al alloy by ultrasonic vibration method. The A356 melt in temperature of 630660°C was poured into a special metal cup, and exposed to ultrasonic vibration at 20 kHz or isothermal holding for a certain time after vibration. The results show that the semi-solid slurry with primary α-Al crystals smaller than 90 μm and an average shape coefficient F S (SF was defined as SF4 A/L2P) above 0.5 could be prepared by ultrasonic vibration for a time less than 144 s. In the isothermal holding period after a short time of ultrasonic vibration, the average particle diameter increased with the increase of holding time, but F S decreased at first, and then increased a little. It was discovered that ultrasonic vibration is a good method to prepare semi-solid slurry with fine and relatively round primary crystals due to cavitation and acoustic streaming effects.
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Authors: Zhi Feng Zhang, Jun Xu, Yue Long Bai, Li Kai Shi
Abstract: An advanced rheo-diecasting technique, based on a modified multi-electromagnetic stirring continuous preparation (MSCP) process was developed for manufacturing near-net shape Al-alloys components with high integrity. The modified MSCP process innovatively combines noncontact electromagnetic stirring and an annular chamber with specially designed profiles to in situ make high quality semisolid slurry, and intensive forced shearing and self-wiping action can be achieved under high shear rate and high intensity of turbulence inside the annular chamber. Three Al-Si alloys with hypoeutectic, eutectic and hypereutectic compositions were tested in this study. The results indicate that, compared with those produced by conventional high-pressure diecasting (HPDC) process, rheo-diecasting samples based on the modified MSCP process have finer and more uniform microstructure.
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Authors: Takahisa Kose, Yasuhiro Uetani, Katsuyuki Nakajima, Kenji Matsuda, Susumu Ikeno
Abstract: Semi-solid slurry of phosphor bronze with fine solid granules for rheocasting was tried to make by passing the low-superheat melt through an opening between a rotating regular octagonal rotor and a circumscribed chill block. The effect of rotational speed on the structure of a solidified small ingot was mainly investigated. The ingot structures were changed from the dendrite of rotor-free condition to the rosette at the rotational speed of 50rpm, and the granular with a mean size of about 50μm at higher than150rpm. The slurries made at 150rpm were rheocast to a cylindrical shape cavity within a die kept at different temperatures from 573 to 1173K by the use of a high pressure casting machine. Microstructures of rheocast cylindrical shape products were granular at the die temperatures lower than 773K and changed to grained one as like recrystallized at higher than 973K. Together with the microstructure change, poor tensile ductility less than 3% at the lowest die temperature was improved up to about 60% at 973K.
237
Authors: Takahisa Kose, Yasuhiro Uetani, Katsuyuki Nakajima, Kenji Matsuda, Susumu Ikeno
Abstract: Semi-solid slurry of phosphor bronze with fine solid granules for rheocasting was tried to make by passing the low-superheat melt through an opening between a rotating regular octagonal rotor and a circumscribed chill block. The effect of rotational speed on the structure of a solidified small ingot was mainly investigated. The ingot structures were changed from the dendrite of rotor-free condition to the rosette at the rotational speed of 50rpm, and the granular with a mean size of about 50μm at higher than150rpm. The slurries made at 150rpm were rheocast to a cylindrical shape cavity within a die kept at different temperatures from 573 to 1173K by the use of a high pressure casting machine. Microstructures of rheocast cylindrical shape products were granular at the die temperatures lower than 773K and changed to grained one as like recrystallized at higher than 973K. Together with the microstructure change, poor tensile ductility less than 3% at the lowest die temperature was improved up to about 60% at 973K.
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Authors: Yasuhiro Uetani, Ryotaro Nagata, Hidetoshi Takagi, Kenji Matsuda, Susumu Ikeno
Abstract: Rheo-extrusions of A7075 aluminum alloy were carried out utilizing semi-solid slurries with different solid granule sizes, which were made by a simple method combined a thin upright tube with a water-cooled tube. Every structure of slurries was granular and average solid granule sizes could be controlled by 0.05 to 0.11mm. These slurries were extruded to round bars at extrusion ratio of 36 and press ram speed of 10mm/s mainly, just after cooling to 833K ( fs > 0.9 ). All of the slurries could easily be extruded to bars with smooth surfaces at much low extrusion forces than those of hot-extrusions. Tensile strength of rheo-extruded bars after solution treatment increased with decreasing of the solid granule size. Peak hardness level at T6 condition equivalent to that of hot-extrusion could be obtained at the finest solid granule size.
291
Authors: Suk Won Kang, Dock Young Lee, Ki Bae Kim
Abstract: In order to produce a high quality and cost effective part in the rheocasting process for an automobile industry it has been important to develop a slurry-on-demand process, which can manufacture the semi-solid slurry having a fine and globular structure of primary solid phase. The morphology of primary solid phase of semi-solid slurry is coarsened and globularized during an isothermal holding process in a solid-liquid region. Accordingly, in this paper, the microstructural evolution of semi-solid slurry during the isothermal holding at a various temperature in solid-liquid region was investigated to examine a coarsening and globularization behavior of primary solid phase. The semi-solid slurry of Al alloy was produced in a slurry maker using a multiplex-type slurry cup that we developed recently. A size of primary solid phase was the finer at the higher holding temperature, but under a constant holding time a roundness degree of primary solid phase was the lower at the lower holding temperature. Also, a coarsening rate of primary solid phase was not considered to be affected significantly by a holding temperature even though a little lower coarsening rate was obtained at the higher holding temperature.
239
Authors: Takahisa Kose, Yasuhiro Uetani, Katsuyuki Nakajima, Kenji Matsuda, Susumu Ikeno
Abstract: Semi-solid slurry with fine solid granules for rheocasting was made from lead-free bismuth bronze by passing the low-superheat melt through an opening between a rotating regular octagonal rotor and a circumscribed chill block. We mainly investigated the effect of rotational speed on the structure of a solidified small ingot. The ingot structures changed from the dendrite of rotor-free condition to the rosette at the rotational speed of 50rpm and to the granular with a mean grain size of about 50m at higher than100 rpm. If the slurry made at 100rpm was rheocast to a disk shape by the use of a high pressure casting machine, the disk had almost uniform granular structures from the center to the edge regions.
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