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![Schematic illustration of the stages of the cooling slope technique [35].](publication/258316014/figure/fig23/AS:1089052040282239@1636661648820/Schematic-illustration-of-the-stages-of-the-cooling-slope-technique-35.jpg)
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Semisolid metal (SSM) processing or thixoforming is widely known as a technology that involves the formation of metal alloys between solidus and liquidus temperatures. For the procedure to operate successfully, the microstructure of the starting material must consist of solid near-globular grains surrounded by a liquid matrix and a wide solidus-to-...
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Raymond Edward Smallman was one of Britain's leading physical metallurgists. His books influenced many generations of undergraduates, and his research group spawned more than a dozen professors of metallurgy and materials science, a university vice-chancellor and at least two directors of major metal companies. Smallman's range was immense and duri...
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... The overheated molten alloy is brought to a semi-solid temperature via the liquid route via mechanical stirring, electromagnetic stirring, ultrasonic stirring methods, chemical grain refining, spray casting [3], shearing-cooling roll [37], swirled enthalpy equilibration device process [38], gas-induced semi-solid process [39], electromagnetic stirring combined with mechanical vibration as mentioned Dao et al. [40], cooling slope casting [41], low superheat casting [42] and several more and can then be thixoformed. ...
The thixoforging of aluminium alloys has received in recent years an extensive interest for the manufacture of parts because of its advantages. To choose an aluminium alloy as raw material for a thixoforming process, it is important to know, the product characteristics, respectively the expected mechanical properties, and secondly, the semi-solid interval and the temperature of fusion. Various wrought and foundry aluminium alloys are thoroughly summarized in this review paper, together with a description of the evaluation methods for the heating temperature sensitivity. Furthermore, for thixoforging industrial applications, the heating strategy is very important, and the reheating regime should be systematically analysed. The advantages offered by thixoforging of aluminium alloys are associated to the feedstock material microstructure that results after reheating to the semi-solid range, which is key to understand the rheological behaviour and the final mechanical properties of the thixoformed parts. In the future, a process model needs to be developed to integrate microstructure conditioning during reheating of the material to the semi-solid state.
... Chemical grain refinement is a well-known technique in the casting industry. This route is usually used in Al-based alloys [4]. The heterogeneous nucleation agent causes suppression of dendritic growth and produces equiaxed, fine grain size microstructures with better distribution of -Al phase in the cast product or solidified ingot. ...
... There are many routes to achieve semisolid process such as mechanical stirring, spray forming, partial melting, magneto hydrodynamic stirring, and strain induced melt activation process (SIMA). [1][2][3][4][5][6][7] The SIMA process involves three stages: casting, warm, or cold deformation and isothermal holding at the temperature between solidus and liquidus temperature. The deformation in the alloy induced the strain energy which is acts as driving force for the spheroidal or recrystallization of structure. ...
... Dislocation is generated due to the misorientations between dendritic arms, if the misorientations is greater than 20°then energy of solid/liquid interface is low as compare to the grain boundary energy and wetting of grain boundary with liquid/solid interface, which leads to the separation of the dendritic arms. 7 Current investigation on the SIMA processed steel and observe the behavior of SIMA processed steel as compare with the as cast steel. The limited literatures are available on the SIMA process on steel, so further studied can be carried out. ...
Strain induced melt activation (SIMA) is the mechanism for the formation of the globular microstructure under the controlled working process followed by holding the specimen at a temperature between solidus & liquidus pertaining to the given alloy system. The effect of SIMA process on the microstructure of steel, 10% and 15% deformed at 900°C and holding at 1400°C for 3 and 5 min separately were investigated. The metallographic examination of the SIMA processed steel was done and compared with the as received steel. It was observed that SIMA processed steel shows the globular structure as compared with the unprocessed steel. It was also found that as the deformation percentage increases, more globular structure forms. Due to the globular microstructure, there is enhancement in the mechanical properties such as tensile strength and hardness. The parameter such as degree of warm working process, temperature and holding time are important factor in controlling SIMA process. During mechanical working in the SIMA process, strain energy gets stored in the material. The 15% deformation with 3 min holding time enhanced the hardness and ultimate tensile strength by approximately 8% respectively as compared with as received sample. This acts as a driving force for recrystallization of warm worked steel which resulted in equiaxed grains of primary phase in the microstructure.
... Several processing routes that were utilized for the production of non-dendritic feedstocks as candidate materials for semisolid processing are reviewed comprehensively in [21]. According to Omar et. ...
... This suggests that there is the potential to increase the range of routes available for the production of thixoformable microstructures. During semisolid cooling, M2 steel underwent intragranular acicular ferrite (IAF) transformation at a very high temperature (1180 960 • C) [21]. Using a confocal laser scanning microscope, the unusual IAF change was seen in action. ...
... A useful software package called Java-based material properties (JMatPro) was adopted to perform some important thermodynamic analyses. It involves various theoretical models for materials and their property database, enabling quantitative computing of the necessary material properties that can be performed over a larger software structure [21]. For D2 tool steel, the liquid fraction profile (LFP) and solidus and liquidus temperatures are calculated using the JMatPro software. ...
The success of the thixoforming process largely depends on the created microstructure, which must be globular in the liquid phase. The solid–liquid structural changes that occur on as-annealed D2 tool steel when it is subjected to the so-called DPRM are described in this work (direct partial remelting method). The paper discusses phase changes and how carbide dissolution affects grain boundary liquation and grain spheroidization. Equiaxed grains with undissolved carbide particles have been found in the microstructural analysis at 1250 °C; however, the carbides gradually disappear as the temperature rises. Additionally, the equiaxed grains were transformed to a globular structure, which improves the shape factor and grain size for the thixoforming process. For AISI D2 thixoforming, which produced grains with a diameter of 50 μm and a shape factor of 1.18, temperatures of 1300 °C and a holding period of 5 min were the optimum parameters. The outcomes also showed that the mechanical properties of the AISI D2 were greatly enhanced after using direct partial remelting, where hardness was increased from 220 Hv to 350 Hv and tensile strength from 791 MPa to 961 MPa.
... Rheocasting merupakan proses semisolid casting yang memanfaatkan agitasi mekanik pada logam setengah padat [7], dengan gaya yang terjadi menghasilkan perubahan bentuk struktur yang lebih halus menjadikan aliran logam lebih mudah mengalir sehingga meningkatkan mampu alir dan mereduksi susutan [8]. Pemrosesan semisolid rheocasting menjadikan sifat tikstropi dalam cairan logam seperti berbentuk bubur atau sluri, pada fasa semi solid ketika gaya geser diberikan maka mekanisme pertumbuhan butir dendrit akan terpecah menjadi globular menjadikannya mudah bergerak mengisi rongga cetakan satu sama lain [9], selain itu dengan temperature dibawah titik lebur dapat meningkatkan umur pakai cetakan [10]. Maka dari itu diperlukan temperature yang tepat dalam prosesnya dengan memperhatikan area transisi dari fasa cair dan padat yang ditunjukan Gambar 2. ...
AbstrakIndustri otomotif sebagian besar pada penggunaan part dan komponen lainnya masih menggunakan paduan aluminium dengan proses pengecoran. Salah satu paduan dengan perlakuan panas yang baik dan karakteristik perbandingan kekuatan dengan berat jenis yang baik yaitu Al-Cu, namun dengan karakteristik demikian paduan ini juga memiliki kekurangan mampu alir dan susutan yang besar. Dalam percobaan ini melakukan proses pengecoran semi-solid rheocast denan variasi lama pengadukan menggunakan paduan al-cu sebagai bahan untuk dilakukan peningkatan mampu alir dan penurunan nilai susutan dari paduan. Dari hasil percobaan didapatkan hasil cukup baik pada mampu alir dengan penambahan panjang aliran logam dengan perbedaan ketebalan cetakan didapatkan nilai paling tinggi dilamanya waktu pengadukan 540 dengan ketebalam 1 mm;9,8mm, 1,5 mm; 15 mm,1,8mm; 17 mm, 2 mm; 22 mm. Penurunan nilai susutan yang didapat juga cukup baik dari hasil proses semi-solid rheocast menghasilkan penurunan sebanyak 48,9% dari tanpa proses rheocasting dengan yang diberikan proses rheocasting menggunakan variasi lama waktu pengadukan. Kata kunci— Al-Cu, Rheocasting, Penyusutan, Mampu Alir Abstract Most of the Automotive Industry use parts and other components still use aluminum alloys with the casting process. One of the alloys with good heat treatment and good characteristics of the ratio of strength to specific gravity is Al-Cu, but with such characteristics this alloy also has a lack of large flowability and shrinkage. In this experiment, a semi-solid rheocast casting process was carried out with various stirring times using al-cu alloy as a material to increase the flowability and reduce the shrinkage value of the alloy. From the experimental results, it was found that the flowability was quite good with the addition of metal flow length with a difference in mold thickness, the highest value was the mixing time of 540 with a thickness of 1 mm; 9.8 mm, 1.5 mm; 15mm,1.8mm; 17mm, 2mm; 22mm. The decrease in shrinkage value obtained was also quite good from the results of the semi-solid rheocast process resulting in a reduction of 48.9% from that without the rheocasting process given the rheocasting process using variations in the length of stirring time. Keywords— Al-Cu, Rheocasting, Shrinkage, Fluidity
... The most crucial step of the semi-solid metal forming process is to obtain the fine, uniform nondendritic globular microstructure. At present, the required globular microstructure can be obtained by either a liquid route [12] or a solid route [13] . Compared to the former, the solid route delivers a relatively compact billet with the benefit of no contamination and wide application possibilities. ...
The Al80Mg5Li5Zn5Cu5 light-weight high-entropy alloy with globular microstructure was fabricated by isothermal heat treatment. The effects of isothermal temperatures and holding times on the semi-solid microstructure evolution were investigated. The results indicate that, with increase of the isothermal temperature, the average grain size increases and the spheroidization time shortens. With prolongation of holding time, the shape factor increases firstly and then decreases, and the average grain size decreases at first and then increases when the isothermal temperature is below 520 °C, however it increases gradually at 540 °C. The optimal semi-solid microstructure is obtained at 520 °C for 30 min, whose shape factor and average grain size are 0.90 and 56.4 µm, respectively. Compared with as-cast Al80Mg5Li5Zn5Cu5 light-weight high-entropy alloy, the compressive strength and plasticity of semi-solid Al80Mg5Li5Zn5Cu5 light-weight high-entropy alloy are increased by 36% and 108%, respectively. The formation of semi-solid microstructures includes three stages: melting separation, spheroidization, and coarsening growth. The sluggish diffusion effect of Al80Mg5Li5Zn5Cu5 light-weight high-entropy alloy leads to a low coarsening rate, resulting in slow grain growth.
... В жидком металле в этом случае возбуждаются полоидальное, и тороидальное течения. При МГД-перемешивании в процессе кристаллизации происходит измельчение зерна в кристаллической структуре слитка, что обеспечивает повышение его механических характеристик [5][6][7]. ...
Для повышения качества непрерывных цилиндрических слитков из алюминия и его сплавов в машинах непрерывного литья в процессе их работы применяется МГД-перемешивание в теплом верхе кристаллизатора. В жидком металле в этом случае возбуждаются полоидальное и тороидальное течения. Эти течения существенно влияют на перенос тепла от поступающего в теплый верх кристаллизатора горячего металла к зоне охлаждения, где формируется фронт кристаллизации. Эксперимент показал, что тороидальное течение сначала снижает скорость продвижения фронта кристаллизации, затем с усилением величины вращающегося поля (усиление тороидального течения) скорость перестает заметно меняться. Полоидальное течение (бегущее магнитное поле) также сначала снижает скорость фронта, но несколько быстрее, чем тороидальное, и на кривой зависимости скорости продвижения фронта от величины бегущего поля есть минимум, после которого скорость продвижения фронта кристаллизации начинает расти. Было обнаружено, что при совместномдействии бегущего и вращающегося магнитных полей скорость продвижения фронта кристаллизации сначала снижается, затем возрастает.
... Billet reheating promotes the formation of globular grain structures. The globular grain structure and the refinement of the grain as the effects of the thixoforming process were proven to increase the mechanical properties of Al alloy [28,31,35]. ...
Thixoforming is a promising method that offers several advantages over both liquid and solid processing. This process utilizes semi-solid behaviour and reduces macrosegregation, porosity and forming forces during the shaping process. Microstructural and mechanical characterization of 0.3, 0.5 and 1.0 wt% graphene nanoplatelet (GNP) reinforced A356 aluminium alloy composite fabricated by thixoforming was investigated. Stir casting was employed to fabricate feedstocks before they were thixoformed at 50% liquid. The microstructure was characterized and evaluated by field emission scanning electron microscopy with an energy dispersive X-ray detector and X-ray diffraction. Mechanical testing, such as microhardness and tensile testing, was also performed to estimate the mechanical properties of the composites. The incorporation of 0.3 wt.% GNPs in Al alloy increased by about 27% in ultimate tensile strength and 29% in hardness. The enhancement in tensile strength is primarily attributed to load transfer strengthening due to the uniform dispersion of these GNPs within the Al matrix, which promotes effective load transfer during tensile deformation, and GNPs’ wrinkled surface structure. Simultaneously, the addition of GNPs enhances the grain refinement effect of the Al alloy matrix, resulting in a grain size strengthening mechanism of the GNPs/Al composites. The results reveal that thixoformed composite microstructure consists of uniformly distributed GNPs, α-Al globules and fine fibrous Si particles. The composites’ grains were refined and equiaxed, and the mechanical properties were improved significantly. This study creates a new method for incorporating GNPs into Al alloy for high-performance composites.
... e Tosa knife, also known as the Achang knife, is called "Mengshuo cap" in Achang language and is named after the Tosa and Lasa areas in Longchuan County, Dehong Dai and Jingpo Autonomous Prefecture, where the Achang people live [1]. According to folklore, historical records, and archaeological objects, the Achang knife is the oldest surviving combat knife in China [2]. ...
With a long history of more than 600 years of development, the Achang Tosa knives have always been handmade and made in strict accordance with tradition and absorbing the essence of foreign cultures. It is not only a tool or a gift, but also a “knife culture” and a local “folk culture” with local ethnic characteristics in Yunnan. In this paper, we begin our research on the Achang Tosa knives by compiling literature and conducting field research to investigate the “knife culture” jointly created by the Achang and neighboring ethnic groups by studying the forging process of the Achang Tosa knives. Three sets of specimens were prepared and the mechanical properties were determined by combining the existing isothermal quenched ductile iron (ADI) material production, and a high-speed cutting test was carried out with a CC650 ceramic tool to investigate the relationship between the machined material, tool material, and cutting dosage-surface roughness during high-speed cutting of ADI; based on the particle swarm algorithm, a theoretical model between surface roughness and cutting parameters was established to provide theoretical guidance for the optimal production process of ADI in high-speed cutting. It provides more valuable experience for the protection of intangible cultural heritage of ethnic minorities and also provides reference for the development and protection of unique crafts of other ethnic minorities.
... The process parameters in the slope casting of semisolid slurry preparation are [21,31,[43][44][45][46][47][48][49]: ...
... Classification of semi solid processes[31]. ...
Semi solid processing is a near net shape casting process and one of the promising techniques to obtain dendritic free structure of metals. Semi solid casting gives numerous advantages than solid processing and liquid processing. Semi solid casting process gives, Laminar flow filling of die without turbulence, Lower metal temperature, Less shrinkage, Less porosity, Higher mechanical properties. Semi solid casting process is industrially successful, producing a variety of products with good quality. Slope Casting process is a simple technique to produce semi solid feed-stoke with globular microstructure and dendrite free structure castings. Slope casting process depends on different process parameters like slope length, slope angle, pouring temperature etc. The present study mainly focuses on review of various explorations made by researchers with different process parameters of the Slope casting process and explain the mechanisms that lead to microstructural changes which leads to good mechanical properties.
