Articoli di riviste: "Solidification defects"

1

Elmquist, Lennart, Kaisu Soivio e Attila Diószegi. "Cast Iron Solidification Structure and how it is Related to Defect Formation". Materials Science Forum 790-791 (maggio 2014): 441–46. http://dx.doi.org/10.4028/www.scientific.net/msf.790-791.441.

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In this work, the meaning of the solidification structure and how it is related to defect formation in grey cast iron will be discussed. The work also confirms observations made earlier. In previous work the formation of shrinkage porosity in grey cast iron cylinder heads was investigated. It was found that the defect is located around solidification units resembling primary austenite grains. The solidification of grey cast iron starts with the formation of primary austenite grains, followed by the eutectic solidification. The primary grains nucleate and grow either as columnar or equiaxed grains, creating a columnar to equiaxed transition between the two zones. Based on the presence of a migrating hot spot, and other characteristics found on the cylinder heads, a geometry was developed that promote the formation of shrinkage porosity. The primary solidification structure, normally transformed during the solid state transformation, was preserved using a technique called Direct Austempering After Solidification (DAAS). After solidification, the samples were cut and prepared for investigation using a Scanning Electron Microscope (SEM) equipped with a detector for Electron Back Scattered Diffraction (EBSD). Individual grains were identified and the primary solidification structure around the defects was revealed. The investigation shows how shrinkage porosity is formed and located between primary austenite grains. This confirms that the primary solidification structure has a large influence on the formation of defects in grey cast iron. The investigation also confirms the correctness of earlier results as well as the validity of the DAAS technique.

2

Nan, Hong Yan, Li Lin Chen, Guo Fa Mi e Jiao Ma. "Application of Numerical Simulation and Optimization on Tensioner Pulley Bracket". Advanced Materials Research 529 (giugno 2012): 186–89. http://dx.doi.org/10.4028/www.scientific.net/amr.529.186.

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This article is about casting process of tensioner pulley bracket, which includes solidification simulation, mould filling simulation and defect forecast, using ViewCast software. The scale and location of the shrinkage defects were shown in simulation results. Solidification results demonstrated that the casting defects were not eliminated by the casting technology. The optimized scheme was obtained by replacing and adding chills. The optimization scheme was calculated and the simulation results shown that the reasonable casting process was obtained and the process has been proofed by the productive practice.

3

Mooraj, Shahryar, Jiaqi Dong, Kelvin Y. Xie e Wen Chen. "Formation of printing defects and their effects on mechanical properties of additively manufactured metal alloys". Journal of Applied Physics 132, n. 22 (14 dicembre 2022): 225108. http://dx.doi.org/10.1063/5.0132137.

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Printing defects are known to degrade the performance of additively manufactured (AM) alloys. Thus, a thorough understanding of their formation mechanisms and effects on the mechanical properties of AM materials is critically needed. Here, we take CoCrFeNi high-entropy alloy as a model material and print this alloy by laser powder bed fusion over a wide range of printing conditions. We reveal the processing windows for the formation of different printing defects including lack of fusion (LOF), keyhole, and solidification cracking. LOF and keyholes can be well correlated with insufficient and excessive laser energy density inputs, respectively. Of particular interest, we observe that solidification cracks only emerge at the medium laser energy density region, where the porosity is minimal yet the grain size and misorientation are relatively large. Such observation is rationalized within the framework of Rappaz–Drezet–Gremaud solidification theory. Among the above printing defects, solidification cracks in AM CoCrFeNi result in less degradation of mechanical properties compared with LOF and keyholes due to their different defect densities and resultant capabilities of coalescence. Our work provides fundamental insight into understanding the physical origins underlying the formation of printing defects and their impacts on the mechanical properties of AM metals and alloys.

4

Meshram, Suresh, e Madhusudhan Reddy. "Influence of Tool Tilt Angle on Material Flow and Defect Generation in Friction Stir Welding of AA2219". Defence Science Journal 68, n. 5 (12 settembre 2018): 512–18. http://dx.doi.org/10.14429/dsj.68.12027.

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Heat treatable aluminium alloy AA2219 is widely used for aerospace applications, welded through gas tungsten and gas metal arc welding processes. Welds of AA2219 fabricated using a fusion welding process suffers from poor joint properties or welding defects due to melting and re-solidification. Friction stir welding (FSW) is a solid-state welding process and hence free from any solidification related defects. However, FSW also results in defects which are not related to solidification but due to improper process parameter selection. One of the important process parameters, i.e., tool tilt angle plays a critical role in material flow during FSW, controlling the size and location of the defects. Effect of tool tilt angle on material flow and defects in FSW is ambiguous. A study is therefore taken to understand the role of tool tilt angle on FSW defects. Variation in temperature, forces, and torque generated during FSW as a result of different tool tilt angles was found to be responsible for material flow in the weld, controlling the weld defects. An intermediate tool tilt angle (1o-2o) gives weld without microscopic defect in 7 mm thick AA2219 for a given set of other process parameters. At this tool tilt angle, x-force, and Z- force is balanced with viscosity and the material flow strain rate sufficient for the material to flow and fill internal voids or surface defects in the weld.

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Yu, J. K., Q. Yan e Pin Yang Fang. "Solidification of Aluminum Infiltrated Composites". Materials Science Forum 475-479 (gennaio 2005): 901–4. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.901.

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The solidification and defects of Al/SiC and Al/C composites were investigated by directional solidification techniques. The solidification and defects of Al/SiC composites are greatly influenced by temperature gradients, solidification rates, the size of SiC particles and the chemical composition of magnesium, but slightly by the volume fraction of SiC particles and the chemical composition of silicon. The solidification shrinkage feeding of Al/C composites is greatly improved by hybridizing carbon fiber bundles with 3 vol% of SiC particles. A model of the solidification feeding was proposed and the solidification feeding distance was derived according to the preform geometry.

6

Huo, Miao, Chuyue Chen, Hangyue Jian, Wenchao Yang e Lin Liu. "The Stray Grains from Fragments in the Rejoined Platforms of Ni-Based Single-Crystal Superalloy". Metals 13, n. 8 (15 agosto 2023): 1470. http://dx.doi.org/10.3390/met13081470.

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Nickel-based single crystal superalloy is the most important material for blade preparation. However, some solidification defects inevitably occur during the process of preparing single-crystal blades through directional solidification. In this study, in order to study the origin of misorientation defects during solidification, a model with rejoined platforms was designed according to the geometry of single-crystal guide vanes. Electron Back-Scattering Diffraction (EBSD) was used to quantify the orientation deviation of the dendrites and identify the solidification defects in the rejoined platforms. The results showed that stray grain defects appeared in the platforms and their misorientation changed gradually, not abruptly. Combined with the simulation results, it was proposed that the stray grains formed as the result of the dendrites fragment, which was induced by solute enrichment in the mushy zone during solidification. Meanwhile, it was accompanied by a obvious dendritic deformation, which was caused by solidification shrinkage stress. This suggested that the fragmentation was induced by multiple factors, among which, the concave interface shape provided favorable conditions for solute enrichment, and the dynamic variability in the local thermal gradient and fluctuations of the solidification rate might play catalytic roles.

7

Korojy, B., L. Ekbom e H. Fredriksson. "Microsegregation and Solidification Shrinkage of Copper-Lead Base Alloys". Advances in Materials Science and Engineering 2009 (2009): 1–9. http://dx.doi.org/10.1155/2009/627937.

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Microsegregation and solidification shrinkage were studied on copper-lead base alloys. A series of solidification experiments was performed, using differential thermal analysis (DTA) to evaluate the solidification process. The chemical compositions of the different phases were measured via energy dispersive X-ray spectroscopy (EDS) for the Cu-Sn-Pb and the Cu-Sn-Zn-Pb systems. The results were compared with the calculated data according to Scheil's equation. The volume change during solidification was measured for the Cu-Pb and the Cu-Sn-Pb systems using a dilatometer that was developed to investigate the melting and solidification processes. A shrinkage model was used to explain the volume change during solidification. The theoretical model agreed reasonably well with the experimental results. The deviation appears to depend on the formation of lattice defects during the solidification process and consequently on the condensation of those defects at the end of the solidification process. The formation of lattice defects was supported by quenching experiments, giving a larger fraction of solid than expected from the equilibrium calculation.

8

Hassan, Mohamed Abubakr, Mahmoud Hassan, Chi-Guhn Lee e Ahmad Sadek. "Monitoring Variability in Melt Pool Spatiotemporal Dynamics (VIMPS): Towards Proactive Humping Detection in Additive Manufacturing". Journal of Manufacturing and Materials Processing 8, n. 3 (29 maggio 2024): 114. http://dx.doi.org/10.3390/jmmp8030114.

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Humping is a common defect in direct energy deposition processes that reduces the geometric integrity of printed products. The available literature on humping detection is deemed reactive, as they focus on detecting late-stage melt pool spatial abnormalities. Therefore, this work introduces a novel, proactive indicator designed to detect early-stage spatiotemporal abnormalities. Specifically, the proposed indicator monitors the variability of instantaneous melt pool solidification-front speed (VIMPS). The solidification front dynamics quantify the intensity of cyclic melt pool elongation induced by early-stage humping. VIMPS tracks the solidification front dynamics based on the variance in the melt pool infrared radiations. Qualitative and quantitive analysis of the collected infrared data confirms VIMPS’s utility in reflecting the intricate humping-induced dynamics and defects. Experimental results proved VIMPS’ proactivity. By capturing early spatiotemporal abnormalities, VIMPS predicted humping by up to 10 s before any significant geometric defects. In contrast, current spatial abnormality-based methods failed to detect humping until 20 s after significant geometric defects had occurred. VIMPS’ proactive detection capabilities enable effective direct energy deposition control, boosting the process’s productivity and quality.

9

Khan, Muhammad Azhar Ali. "Simulation Based Mold Design Optimization of a Spring Flap Casting". Solid State Phenomena 305 (giugno 2020): 178–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.305.178.

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The complex nature of metal casting process brings about a need to simulate it before undertaken in a foundry. Casting simulations provide insights on flow of molten metal within the mold, solidification sequence, nature and location of defects etc. Moreover, mold design can be optimized to minimize defects without undergoing physical trials-and-errors as previously practiced in traditional metal casting. This study is based on casting an ASTM A216 WCB steel spring flap for automotive suspension system using a simulation based optimized mold design. The initial and optimized mold designs are simulated in MAGMASoft for mold filling, solidification, stress distribution and defects prediction. The results of simulations and actual castings are found to be in good agreement. It is concluded that simulations are accurate in modeling casting process and in predicting defects followed by their minimization through mold design optimization. The use of auxiliary components in a carefully designed mold can lead to a nearly defect-free and high quality cast product.

10

Xu, Qing Yan, Bai Cheng Liu, Zuo Jian Liang, Jia Rong Li, Shi Zhong Liu e Ha Llong Yuan. "Modeling of Unidirectional Growth in a Single Crystal Turbine Blade Casting". Materials Science Forum 508 (marzo 2006): 111–16. http://dx.doi.org/10.4028/www.scientific.net/msf.508.111.

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Single crystal superalloy turbine blade are widely used in aero-engineering. However, there are often grain defects occurring during the fabrication of blade by casting. It is important to study the formation of microstructure related defects in turbine blades. Single crystal blade sample castings of a nickel-base superalloy were produced at different withdrawal rates by the directional solidification process and investment casting. There was a difference between the microstructure morphology at the top part of the turbine blade sample castings and the one at the bottom. Higher withdrawal rates led to more differences in the microstructure and a higher probability of crystallographic defect formation such as high angle boundaries at locations with an abrupt change of the transversal section area. To further investigate the formation of grain defects, a numerical simulation technique was used to predict the crystallographic defects occurring during directional solidification. The simulation results agreed with the experimental ones.

11

Yuan, Lang. "Solidification Defects in Additive Manufactured Materials". JOM 71, n. 9 (23 luglio 2019): 3221–22. http://dx.doi.org/10.1007/s11837-019-03662-x.

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Wable, Girish S., Srinivas Chada, Bryan Neal e Raymond A. Fournelle. "Solidification shrinkage defects in electronic solders". JOM 57, n. 6 (giugno 2005): 38–42. http://dx.doi.org/10.1007/s11837-005-0134-x.

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13

Chen, Wei, Shiping Wu e Rujia Wang. "Effect of Mechanical Vibration on the Mechanical Properties and Solidification Feeding in Low-Pressure Sand Casting of Al-Cu-Mn-Ti Alloy". Materials 15, n. 22 (20 novembre 2022): 8243. http://dx.doi.org/10.3390/ma15228243.

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The shrinkage defects of Al-Cu-Mn-Ti alloy seriously hinder its application in high-performance engineering. In this study, mechanical vibration was introduced to low-pressure sand casting (LPSC) by a waveguide rod to eliminate shrinkage defects and improve mechanical properties. Four LPSC castings were performed by changing the solidification conditions: 20 kPa solidification pressure without and with 14 Hz vibration and 40 kPa without and with 24 Hz (the natural frequency of a casting system) vibration. The shrinkage defects, microstructures, and mechanical tensile properties at room temperature and at 2 mm/min tensile rate were investigated. X-ray detections showed that applying vibration was more effective than increasing solidification pressure in improving solidification feeding, while the most effective method was applying both simultaneously, which eliminated the shrinkage defects and increased the density by 2.7%. Microstructures exhibited that the average size of primary α-Al grains were reduced by 29.5%; mechanical tests showed that the ultimate tensile strength and the elongation increased by 21.7% and 7.8%, respectively, by applying vibration and increasing the solidification pressure simultaneously, as compared to the casting with 20 kPa solidification pressure without vibration. Mechanical vibration was conducive to mass feeding by refining the primary grains, to interdendritic feeding by reducing the threshold pressure gradient, and to burst feeding by collapsing the barrier.

14

Luo, Yiming, Ronghui Ju, Bingbo Li, Junjiong Meng e Xuanjun Wang. "Thermal Decomposition and Solidification Characteristics of BFFO". Crystals 13, n. 5 (10 maggio 2023): 802. http://dx.doi.org/10.3390/cryst13050802.

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A novel energetic material, Bifurazano [3,4-b: 3′,4′-f] furoxano [3″,4″-d] oxacyclo-heptatriene (BFFO), has been investigated regarding two aspects, namely its thermal decomposition and solidification characteristics. The DSC curves indicate that the peak temperature of BFFO decomposition process is 271.1 °C under the static pressure of 2 MPa and the volatility of BFFO at 120 °C is significantly lower than that of TNT, DNAN and DNTF. The solidification curve indicates that the solidification of BFFO is a basic linear uniform solidification process, which is obviously different from that of TNT, DNAN and DNTF. In addition, the facet of BFFO appears much smoother and fewer defects are observed in the solidified body after solidification via CT and SEM. The reduction in solidification defects also further improves the mechanical properties of BFFO, with significant improvements in compressive and tensile strength compared to DNTF, DNAN and TNT. In summary, BFFO is a potential melt-cast carrier explosive with excellent thermal stability, solidification characteristics and mechanical properties.

15

Liao, Qiang, Peng Ge, Guangxuan Lu, Yang Song, Wenhui Ye, Jianping Gao e Xian Luo. "Simulation Study on the Investment Casting Process of a Low-Cost Titanium Alloy Gearbox based on ProCAST". Advances in Materials Science and Engineering 2022 (20 settembre 2022): 1–10. http://dx.doi.org/10.1155/2022/4484762.

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A model of investment casting of a titanium alloy gearbox based on the ProCAST software was established in this work, and the simulated result was used to optimize the casting process. The flow and temperature field of casting were simulated based on an actual pouring process. Casting defects and the solidification process were analyzed. The results show that the defects can be predicted by the simulation result exactly, and the simulated temperature field is in accordance with the actual process. Shrinkage and porosity are observably alleviated by remodelling the casting mould. The casting temperature field and solidification simulation results show that the casting defects arise from hot spots and heat accumulation. The temperature-time curve of different representative location nodes of casting further confirms the defect simulation results. In addition, the use of low-cost alloy elements reduces raw material costs. Compared with TC4 alloy, the mechanical properties of the casting remain unchanged.

16

Lou, Bai Yang, Fang Li Liu e Kang Chun Luo. "Numerical Simulation of Mold Filling and Solidification Process of a Disc Aluminum Alloy in Pressure Die Casting". Applied Mechanics and Materials 121-126 (ottobre 2011): 254–58. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.254.

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The numerical simulations of mold filling and solidification process for the A380 aluminum alloy were done by the supposed mathematical model. The casting defects in the process of mold filling and solidification were predicted by the result of the casting simulation. The casting defects of simulation are well compared with the practice. Some measures presented were improved for the existing technological process.

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Parisi, A., e M. Plapp. "Defects and multistability in eutectic solidification patterns". EPL (Europhysics Letters) 90, n. 2 (1 aprile 2010): 26010. http://dx.doi.org/10.1209/0295-5075/90/26010.

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Sabau, Adrian S. "Predicting interdendritic cavity defects during casting solidification". JOM 56, n. 3 (marzo 2004): 54–56. http://dx.doi.org/10.1007/s11837-004-0035-4.

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Lewis, Daniel. "Solidification defects revisited and semi-solid processing". JOM 58, n. 6 (giugno 2006): 12. http://dx.doi.org/10.1007/s11837-006-0171-0.

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Szeliga, D., K. Kubiak e J. Sieniawski. "Numerical Simulation of Directional Solidification Process of Single Crystal Ni- Based Superalloy Casting". Archives of Foundry Engineering 17, n. 2 (27 giugno 2017): 111–18. http://dx.doi.org/10.1515/afe-2017-0061.

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Abstract The analysis of influence of mould withdrawal rate on the solidification process of CMSX-4 single crystal castings produced by Bridgman method was presented in this paper. The predicted values of temperature gradient, solidification and cooling rate, were determined at the longitudinal section of casting blade withdrawn at rate from 1 to 6mm/min using ProCAST software. It was found that the increase of withdrawal rate of ceramic mould results in the decrease of temperature gradient and the growth of cooling rate, along blade height. Based on results of solidification parameter G/R (temperature gradient/solidification rate), maximum withdrawal rate of ceramic mould (3.5 mm/min), which ensures lower susceptibility to formation process of new grain defects in single crystal, was established. It was proved that these defects can be formed in the bottom part of casting at withdrawal rate of 4 mm/min. The increase of withdrawal rate to 5 and 6 mm/min results in additional growth of susceptibility of defects formation along the whole height of airfoil.

21

Liu, Zi Kang, Min Luo, Da Quan Li, Long Fei Li e Jian Feng. "Effects of Process Parameters on Shrinkage Porosity in 357 Semi-Solid Die Casting Parts". Materials Science Forum 993 (maggio 2020): 166–71. http://dx.doi.org/10.4028/www.scientific.net/msf.993.166.

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The shrinkage porosity that was caused by the insufficient feeding during solidification, was a common defect in the semi-solid die casting process. This defect decreased significantly the mechanical properties of the casting. In order to avoid the shrinkage porosity in casting, the die design, slug preparation and die casting process were carefully considered. In this study, a designed mold was used to make the sequential solidification of the slug. The process parameters, including intensification pressure, die temperature and biscuit thickness of the casting, were studied to show their influence on shrinkage porosity defects. The experimental results show that the high intensification pressure, high die temperature and long biscuit can be beneficial to obtain castings with no shrinkage porosity.

22

Yu, Xin Gang, Lan Yun Liu, Yan Bin Zuo, Zhi Peng Xie, Bo Lin Wu, Jin Long Yang, Jian Bao Li, Yong Huang, Lin Wang e Yi Gong. "On the Defects in Injection-Moulded Technical Ceramics". Key Engineering Materials 336-338 (aprile 2007): 1025–27. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1025.

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A heated sprue device for ceramic injection moulding was used to research the defects in injection-moulded technical ceramics. By use of the heated sprue device, the problem of sprue solidification was resolved and the density of the injection moulding specimens was increased while the defects eliminated. The influence of the processing parameters on the defects of the injection molding specimens was investigated in detail by X-ray radiography camera and photograph. It turns that the sprue solidification time has much influence on the defects in injection-moulded technical ceramics. Reasons causing the results above were also analyzed. Based on the research, bars of 20mm in diameter without macroscopic defects and turbine blade of fine property with Si3N4/SiC(w) materials were prepared by injection moulding.

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Nourian-Avval, Ahmad, e Ali Fatemi. "Characterization and Analysis of Porosities in High Pressure Die Cast Aluminum by Using Metallography, X-Ray Radiography, and Micro-Computed Tomography". Materials 13, n. 14 (9 luglio 2020): 3068. http://dx.doi.org/10.3390/ma13143068.

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Mechanical performance of cast aluminum alloys is strongly affected by the defects formed during solidification. For example, fractography studies of the fatigue specimens have shown that fatigue failure in aluminum castings containing defects is almost always initiated from defects, among which pores are most detrimental. However, elimination of these pores is neither always economically nor technically possible. This work characterizes defects in high pressure die cast aluminum alloy as an illustrative material, but the methods used can be applicable to other types of castings and defects. The defects were evaluated using metallography as well as micro-computed tomography techniques. The variability of defects between the specimens of two sizes as well as different porosity levels are studied statistically. The distributions of defects based on location within the specimens are also analyzed. Moreover, the maximum defect size within the specimens are estimated using extreme value statistics, which can be used as an input to fatigue life prediction models. Extreme value statistics is applied on both 2D and 3D defect data. The accuracy of each approach is verified by comparing the estimated maximum defect size within the specimens with the maximum observed defects on fracture surfaces of fatigue specimens.

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Ridolfi, Maria Rita. "The Formation of the Solidification Microstructure from Liquid Metal in Industrial Processes". Materials Science Forum 884 (gennaio 2017): 115–31. http://dx.doi.org/10.4028/www.scientific.net/msf.884.115.

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This paper focuses on the role played by the liquid metal management on the solidification microstructure in industrial solidification processes. In particular attention is paid to the elimination of solidification defects by governing the microstructure evolution through fluid-dynamics and heat and mass transport in the liquid. The formation of hot tearing and gas porosities as well as columnar and equiaxed microstructures and micro and macro segregation are analyzed to explain how the liquid management is used to avoid defects. Examples on continuous casting and welding are also included.A very powerful tool for dealing with the complex phenomena associated with the solidification process is numerical modeling. Its increasingly growing use contemplates fluid-dynamics of the liquid phase, mass transport of solutes and solid-liquid interface evolution. Models using phase field and volume-averaging techniques, as well as models integrating multi-physics and multi-scale phenomena, are described as their use is taking on increasing importance in the design of solidification processes.

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Wang, Fei Fei, Yan Wei Sui, Yao Jian Ren, Xin Zhao e Zhi Sun. "Defects Analysis and Improvement for Electricmotorcar Aluminum Alloy Wheel by Gravity Casting". Advanced Materials Research 189-193 (febbraio 2011): 3880–85. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.3880.

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Analysis the electricmotorcar aluminum wheels’ hole defect on macroscopic and microscopic, observed that the main defects、concentrated site and the main alloy phase. Combined with the local casting technological parameters, the filling and solidification process of aluminium alloy hub was simulated by using Anycasting software. The results showed that: castings filling smoothly, at the junction of the spoke and the rim and the hub central are easy to produce casting defects. Using the optimized process parameters that is lower pouring temperature, higher pouring height and set the vent to experiment, after comparing the results with the original process known, Shrinkage and porosity defects decreased, but there are still some degree of defects, indicating optimized process parameters have some effect.

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Sabzi, Hossein Eskandari, e Pedro E. J. Rivera-Díaz-del-Castillo. "Defect Prevention in Selective Laser Melting Components: Compositional and Process Effects". Materials 12, n. 22 (18 novembre 2019): 3791. http://dx.doi.org/10.3390/ma12223791.

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A model to predict the conditions for printability is presented. The model focuses on crack prevention, as well as on avoiding the formation of defects such as keyholes, balls and lack of fusion. Crack prevention is ensured by controlling the solidification temperature range and path, as well as via quantifying its ability to resist thermal stresses upon solidification. Defect formation prevention is ensured by controlling the melt pool geometry and by taking into consideration the melting properties. The model’s core relies on thermodynamics and physical analysis to ensure optimal printability, and in turn offers key information for alloy design and selective laser melting process control. The model is shown to describe accurately defect formation of 316L austenitic stainless steels reported in the literature.

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Weiß, K., e Christoph Honsel. "New Algorithm to Calculate Liquid – Solid Shrinkage and Graphite Expansion". Materials Science Forum 508 (marzo 2006): 509–14. http://dx.doi.org/10.4028/www.scientific.net/msf.508.509.

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Meanwhile the calculation of cooling and solidification is a well introduced tool into the foundry industry for calculating gating and riser systems. However, knowing the areas of last solidification is often no answer to the question if there are any defects in the casting or not. Of course one requirement is an exact description of the heat flow and the heat transfer between melt and mould. But furthermore the liquid/liquid and liquid/solid shrinkage influence the temperature fields due to a convective heat flux. Also auxiliary material influence the liquid/solid behaviour. Auxiliary materials can be on one hand the inoculation material and on the other chills with and without coating. This is the reason, why defects near the gating often can not be detected by a conventional solidification calculation, which doesn’t take into account the impact of the auxiliary material on the convective flow. With new algorithms within the FEM program SIMTEC/WinCast it is possible to respect this behaviour during the simulation of solidification. Special attention was turned to the expansion of graphite in ductile irons. The graphite first nucleates in the liquid, and then continues to grow in the solid phase depending on the alloy compositions and the solidification parameters. With the knowledge about the physical properties of the alloy the location and the size of defects can be predicted precisely.

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Marcolin, Patrícia, Marielen Longhi, Lucas Pandolphi Zini, Sandra Raquel Kunst, Ademir José Zattera, Luciana Taís Fuhr, Tiego V. Fillmann e Cláudia Trindade Oliveira. "Effects of the Casting Temperature in the Leakage of Zamak 5". Materials Science Forum 899 (luglio 2017): 458–62. http://dx.doi.org/10.4028/www.scientific.net/msf.899.458.

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Recent studies evidenced that the Zamak 5 corrosion is associated to solidification defects arising from the injection process that occur mainly in areas where the solidification rate is faster. Given this factor, the aim of this research was to evaluate the influence of Zamak 5 casting temperature. For this study, Zamak 5 was casted at different temperatures (430 °C, 450 °C, 500 °C, 550 °C) with respective solidification curves. Zamak 5 was analyzed for chemical composition and microstructure. Moreover, complementary tests of microhardness and electrochemical analyses of open circuit potential and polarization were performed. From these analyses it was observed that the highest casting temperature of Zamak 5 originates larger grains and higher microhardness value, due to the lower solidification rate. In none of the leaking temperatures porosity defects were observed on the samples, which is coherent with previous researches, being originated from the injection process.

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Krenckel, Patricia, Yusuke Hayama, Florian Schindler, Theresa Trötschler, Stephan Riepe e Noritaka Usami. "Propagation of Crystal Defects during Directional Solidification of Silicon via Induction of Functional Defects". Crystals 11, n. 2 (22 gennaio 2021): 90. http://dx.doi.org/10.3390/cryst11020090.

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The introduction of directional solidified cast mono silicon promised a combination of the cheaper production via a casting process with monocrystalline material quality, but has been struggling with high concentration of structural defects. The SMART approach uses functional defects to maintain the monocrystalline structure with low dislocation densities. In this work, the feasibility of the SMART approach is shown for larger ingots. A G2 sized crystal with SMART and cast mono silicon parts has been analyzed regarding the structural defects via optical analysis, crystal orientation, and etch pit measurements. Photoluminescence measurements on passivated and processed samples were used for characterization of the electrical material quality. The SMART approach has successfully resulted in a crystal with mono area share over 90% and a confinement of dislocation structures in the functional defect region over the whole ingot height compared to a mono area share of down to 50% and extending dislocation tangles in the standard cast mono Si. Cellular structures in photoluminescence measurements could be attributed to cellular dislocation patterns. The SMART Si material showed very high and most homogeneous lifetime values enabling solar cell efficiencies up to 23.3%.

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Yang, Qiang, Xintao Zhu, Fu Wang, Dexin Ma e Jiantao Wu. "A Study of Sliver in C-Shaped Grain Selectors during Investment Casting of Single-Crystal Superalloy". Metals 13, n. 6 (12 giugno 2023): 1102. http://dx.doi.org/10.3390/met13061102.

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In this study, the formation mechanism of sliver defects in C-shaped 2D grain selectors during investment casting of single-crystal superalloy was investigated by analyzing the effects of the C-shaped 2D grain selectors on the solidification behavior of superalloy. The physical field properties of the sliver formation and solidification characteristics of CM247LC nickel-based superalloy were determined. The temperature and stress fields were simulated using ProCAST. The results showed that the stress fields of solidification played an essential role in the formation of sliver, indicating that the solidification interval characteristics of the alloy and stress based on the geometry of the C-shaped 2D grain selector are crucial for the formation of sliver. In addition, the origin of sliver depended upon tensile stress during solidification, relying on the constraints of dendrite boundaries. The findings suggested that the joint sections of the starter block—i.e., selector and selector-casting joint of C-shaped selector sections—are stress-sensitive areas where sliver can form readily. Furthermore, sliver is formed in the final stages of solidification and especially originates in the grain selection part where the accumulated thermal stress is high, and there is only a small quantity of liquid phase with a low melting point between the dendrites. Therefore, the solidification and stress conditions generate thermal cracks, which can also cause sliver defects.

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Futas, Peter, Alena Pribulova, Vladimir Sabik, Jozef Petrik, Peter Blasko e Marcin Brzeziński. "Elimination of Shrinkage in Ductile Iron Castings Using Computer Simulation of Casting and Solidification". Processes 12, n. 3 (29 febbraio 2024): 506. http://dx.doi.org/10.3390/pr12030506.

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The production of high-quality castings without foundry defects at minimal production costs is a constant priority for foundries. Innovation and optimization of production processes are key to achieving this goal. Computer simulation of foundry processes offers a modern alternative to expensive and time-consuming experiments in real foundries and provides a reliable representation and analysis of casting and solidification processes. A detailed analysis of the casting and solidification simulation results allows the prediction of various risks that can cause defects in cast castings, thereby reducing their quality and, last but not least, the cost of their production. This paper deals with the analysis of a computer simulation of the casting of a brake disc in a Slovak foundry. This brake disc has had shrinkages and micro shrinkages that reduce the internal quality of the casting. These defects occurred in the ribs in the upper part of the casting under the feeders. A computer simulation of the casting and solidification of this casting was made according to the real conditions. It turned out that the designed gating system with a system of feeders was not sufficient to eliminate the emerging defects. A new layout for the feeders was proposed, which ultimately eliminated the occurrence of defects based on the results of the computer simulation. The input parameters were set to be as close as possible to the actual needs of the foundry. Moreover, 3D models of the assemblies were designed in SolidWorks Premium 2015 x64 Edition CAD software, and the filling and solidification simulations were performed using the NovaFlow & Solid CV 4.6r42 simulation program.

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Sowa, Leszek, Tomasz Skrzypczak e Paweł Kwiatoń. "Computer evaluation of the influence of liquid metal movements on defects formation in the casting". MATEC Web of Conferences 254 (2019): 02017. http://dx.doi.org/10.1051/matecconf/201925402017.

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This paper concerns the modelling of the solidification process including the phenomena of heat transfer and fluid flow during the initial stage of the metal casting process. During this period, the molten metal motions have an essential influence on solidification kinetics. An analysis of solidification kinetics, by determining the velocity and temperature fields in a system of riser-casting was made. Velocity fields were obtained by solving the momentum equations and the continuity equation, while the thermal fields were obtained by solving the conduction equation containing the convection term. After completion of the filling process the main solidification of molten metal takes place and its shrinkage. The phenomenon of casting shrinkage cannot be avoided, but it is possible to minimize its negative effects on the casting quality. One with ways to solve this problem is to design the mould in such a way that the solidification proceeds in accordance to the assumed direction and finished in the riser. Generally, the aim of search is to obtain a casting without shrinkage defects.

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Adegoke, Olutayo, Joel Andersson, Håkan Brodin e Robert Pederson. "Review of Laser Powder Bed Fusion of Gamma-Prime-Strengthened Nickel-Based Superalloys". Metals 10, n. 8 (23 luglio 2020): 996. http://dx.doi.org/10.3390/met10080996.

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This paper reviews state of the art laser powder bed fusion (L-PBF) manufacturing of γ′ nickel-based superalloys. L-PBF resembles welding; therefore, weld-cracking mechanisms, such as solidification, liquation, strain age, and ductility-dip cracking, may occur during L-PBF manufacturing. Spherical pores and lack-of-fusion voids are other defects that may occur in γ′-strengthened nickel-based superalloys manufactured with L-PBF. There is a correlation between defect formation and the process parameters used in the L-PBF process. Prerequisites for solidification cracking include nonequilibrium solidification due to segregating elements, the presence of liquid film between cells, a wide critical temperature range, and the presence of thermal or residual stress. These prerequisites are present in L-PBF processes. The phases found in L-PBF-manufactured γ′-strengthened superalloys closely resemble those of the equivalent cast materials, where γ, γ′, and γ/γ′ eutectic and carbides are typically present in the microstructure. Additionally, the sizes of the γ′ particles are small in as-built L-PBF materials because of the high cooling rate. Furthermore, the creep performance of L-PBF-manufactured materials is inferior to that of cast material because of the presence of defects and the small grain size in the L-PBF materials; however, some vertically built L-PBF materials have demonstrated creep properties that are close to those of cast materials.

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Rao, Lei, Lian Bing Zhu, Xiao Long Li e Qi Yao Hu. "The Defects Analysis and Numerical Simulation of Automobile Brake Hydro Cylinder in Permanent Casting". Materials Science Forum 704-705 (dicembre 2011): 82–87. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.82.

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Brake hydro cylinder is the key part of automobile hydraulic braking system, which usually works under high pressure condition. So, high safety factor of it is required to avoid accident. There are many kinds of casting defects such as shrinkage cavity, gas entrapment and slag enclosure are formed in the mold filling and solidification processes, which contribute to final casting performance. Based on the mathematical models of molding filling and solidification processes, the numerical simulation has been done. In the meanwhile, the defects forming reasons have been analyzed. According to the simulation results, two types of improved schemes have been analyzed and practiced respectively, and its work piece defects were reduced largely. It is an effective way to improve the casting quality by advanced computer technology.

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Ma, De Xin, Bin Zhou e Andreas Bührig-Polaczek. "Development and Application of Heat-Conductor Technique for Single Crystal Components of Superalloys". Advanced Materials Research 278 (luglio 2011): 306–11. http://dx.doi.org/10.4028/www.scientific.net/amr.278.306.

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During single crystal (SC) solidification in turbine blades of superalloys, grain defects often form in the platform region with abrupt variation in cross-section. In order to reduce grain defects induced by component geometries, a Heat Conductor (HC) technique was developed and applied to the production of SC turbine blades. The corresponding ceramic shell moulds were produced by a modified investment casting procedure. The heat conductors with excellent heat conductivity were inserted close to the inner corners of the platform, to effectively extract the local heat during directional solidification. Both computer simulation and temperature measurements have shown that this technique is able to produce a clear improvement of the thermal condition in the critical region of the components. The SC growth in the blade body can spread into the platform more quickly before the melt at the extremity becomes deeply undercooled. Microstructure investigations reveal a remarkable reduction in grain defect formation, providing confirmation of the effectiveness of the HC technique in improving the casting quality of SC components.

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Yu, Daliang, Wen Yang, Wanqing Deng, Songzhu Zhu, Qingwei Dai e Dingfei Zhang. "Crack Initiation Mechanism in Casting AC4B Aluminum Alloy Parts with Complex Structure". Metals 11, n. 1 (6 gennaio 2021): 97. http://dx.doi.org/10.3390/met11010097.

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Hot tears were frequently formed in Aluminum (Al) parts with complex structure. In this study, OM (optical microscope), SEM (scanning electron microscope), EDS (energy dispersive spectrometer), and FDM (finite difference method) were used to reveal the hot tears mechanisms in the casted AC4B Al engine. Shrinkage porosities with the size of 300–500 μm were found in casted specimens near the parts’ surface. Many cracked brittle Fe-bearing phase were also found in crack section. The secondary dendrite arm spacing observation in five typical positions showed that the cooling rate in position 5 was faster than that in position 1. The impropriety solidification sequence in position 5 and position 1 impeded the solidification feeding of position 1, and it might lead to casting defects or even casting cracks. Numerical simulation also showed that solidification sequence promoted casting defects, which was accordant with microstructure observation. Impurity may concentrate at position 5 during filling. It is concluded that large β-Fe intermetallics and improper solidification sequence together contributed to crack initiation in the engine.

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Huang, Binting, Jishi Yang, Zhiheng Luo, Yang Wang e Nan Wang. "Formation of Twin Boundaries in Rapidly Solidified Metals through Deformation Twinning". Materials 16, n. 13 (21 giugno 2023): 4503. http://dx.doi.org/10.3390/ma16134503.

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The rapid solidification process is relevant to many emerging metallurgical technologies. Compared with conventional solidification processes, high-density microstructure defects and residual thermal stress are commonly seen in rapidly solidified metals. Among the various defects, potentially beneficial twin boundaries have been observed in the rapidly solidified nanocrystalline microstructures of many alloy systems. In this work, a pathway for forming twin boundaries in rapid solidification processes is proposed. A detailed derivation of strain inhomogeneities upon thermal shrinkage and the deformation twinning phase field method is given. By calculating cooling-induced thermal strain inhomogeneity in nanocrystalline metals and growth thresholds for deformation twinning using the phase field method, it is shown that residual thermal strain hotspots in the microstructure can reach the threshold for deformation twinning when the shear elastic property of grain boundaries is significantly different from the bulk.

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Ma, De Xin, Qiang Wu e Andreas Bührig-Polaczek. "Undercoolability of Superalloys and Solidification Defects in Single Crystal Components". Advanced Materials Research 278 (luglio 2011): 417–22. http://dx.doi.org/10.4028/www.scientific.net/amr.278.417.

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The undercooling behaviour of the superalloys IN 939 and CMSX-6 during the isothermal heating and cooling processes was investigated. Under the same process conditions, the undercoolability of CMSX-6 was measured to be 50.4 K while that of IN 939 was only 10.1 K. This great difference can be attributed to the amount of alloying elements. During Bridgman directional solidification using the same process parameters, the used alloys exhibited a very different tendency to form structure defects. While the CMSX-6 components were nearly defect-free, the IN 939 samples of the same geometry were very prone to stray grain formation. This difference can be attributed to the different undercoolability of the investigated superalloys. Therefore, the undercoolability is an important factor of castability and the cast quality of single crystal components can be effectively improved by increasing the undercoolability of the superalloys.

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Feng, Shikang, Enzo Liotti e Patrick S. Grant. "X-ray Imaging of Alloy Solidification: Crystal Formation, Growth, Instability and Defects". Materials 15, n. 4 (10 febbraio 2022): 1319. http://dx.doi.org/10.3390/ma15041319.

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Synchrotron and laboratory-based X-ray imaging techniques have been increasingly used for in situ investigations of alloy solidification and other metal processes. Several reviews have been published in recent years that have focused on the development of in situ X-ray imaging techniques for metal solidification studies. Instead, this work provides a comprehensive review of knowledge provided by in situ X-ray imaging for improved understanding of solidification theories and emerging metal processing technologies. We first review insights related to crystal nucleation and growth mechanisms gained by in situ X-ray imaging, including solute suppressed nucleation theory of α-Al and intermetallic compound crystals, dendritic growth of α-Al and the twin plane re-entrant growth mechanism of faceted Fe-rich intermetallics. Second, we discuss the contribution of in situ X-ray studies in understanding microstructural instability, including dendrite fragmentation induced by solute-driven, dendrite root re-melting, instability of a planar solid/liquid interface, the cellular-to-dendritic transition and the columnar-to-equiaxed transition. Third, we review investigations of defect formation mechanisms during near-equilibrium solidification, including porosity and hot tear formation, and the associated liquid metal flow. Then, we discuss how X-ray imaging is being applied to the understanding and development of emerging metal processes that operate further from equilibrium, such as additive manufacturing. Finally, the outlook for future research opportunities and challenges is presented.

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Han, Dong Dong, Cheng Jun Wang, Juan Chang, Lei Chen e Huai Bei Xie. "Numerical Simulation of Filling and Solidification in Sand Casting by Procast". Advanced Materials Research 791-793 (settembre 2013): 550–53. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.550.

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At present, pulley produced in China has been able to meet the demand of domestic and international markets. But there are many problem of the pulley industry in our country, such as too many production enterprises and the low level of export products. And as components of drive system are light weight and raw material price of pulley casting are rising, manufacturing requirements of the pulley are also more and more high. Aiming at the casting defects of pulley that enterprise current product, pulley casting blank model of common material HT250 be made by three-dimension software, numerical simulation of filling and solidification process for pulley sand casting by the casting simulation software Procast, the size and location of the various casting defects were forecasted and analyzed, reflecting the pulley filling and solidification process of the actual situation, due to the thicker pulley rim and less heat dissipation, position of shrinkage is close to the middle of rim [, a method of eliminating defects is proposed to realize sequential solidification, and thus to minimize porosity shrinkage and improve casting performance and reduce casting time and reduce production costs.

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Mechighel, Farid, Mahfoud Kadja, Mohammed El Ganaoui e Bernard Pateyron. "Study of Macrosegregation Defects Formation Caused by Double Diffusive Convective Flow during Solidification of a Binary Alloy". Defect and Diffusion Forum 283-286 (marzo 2009): 340–45. http://dx.doi.org/10.4028/www.scientific.net/ddf.283-286.340.

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Numerical study of both the solidification of the binary alloy Al-4.1%wtCu and macrosegregation defects formation have been carried out. The mixture continuum model was used in the development of the mathematical model representing the solidification phenomena. This model included the conservative equations (mass, momentum, energy and species); these equations were numerically solved by using a finite volume approach.

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Arpita. "Simulation of vertical centrifugal casting using ANSYS". International Journal of Science and Research Archive 11, n. 1 (28 febbraio 2024): 2290–303. http://dx.doi.org/10.30574/ijsra.2024.11.1.0327.

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Axis-symmetric products are often made by means of centrifugal casting, which involves heating and transferring molten metal into a rapidly rotating mould. Centrifugal casting defects are mostly associated with the solidification process. However, when employing experimental techniques for centrifugal casting, determining the process of solidification pace and duration is quite challenging. Simulations may be used to analyze and optimize operational conditions.

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Sun, Chi, Zhanyi Cao, Yanzhu Jin, Hongyu Cui, Chenggang Wang, Feng Qiu e Shili Shu. "Numerical Simulation of Lost-Foam Casting for Key Components of A356 Aluminum Alloy in New Energy Vehicles". Materials 17, n. 10 (15 maggio 2024): 2363. http://dx.doi.org/10.3390/ma17102363.

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The intricate geometry and thin walls of the motor housing in new energy vehicles render it susceptible to casting defects during conventional casting processes. However, the lost-foam casting process holds a unique advantage in eliminating casting defects and ensuring the strength and air-tightness of thin-walled castings. In this paper, the lost-foam casting process of thin-walled A356 alloy motor housing was simulated using ProCAST software (2016.0). The results indicate that the filling process is stable and exhibits characteristics of diffusive filling. Solidification occurs gradually from thin to thick. Defect positions are accurately predicted. Through analysis of the defect volume range, the optimal process parameter combination is determined to be a pouring temperature of 700 °C, an interfacial heat transfer coefficient of 50, and a sand thermal conductivity coefficient of 0.5. Microscopic analysis of the motor housing fabricated using the process optimized through numerical simulations reveals the absence of defects such as shrinkage at critical locations.

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Hellström, Kristina, Péter Svidró, Lucian Vasile Diaconu e Attila Diószegi. "Density Variations during Solidification of Grey Cast Iron". Materials Science Forum 925 (giugno 2018): 155–62. http://dx.doi.org/10.4028/www.scientific.net/msf.925.155.

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As part of moving towards a sustainable production of diesel engines for heavy vehicle applications, the ability to predict casting defects has become ever so important. In order to model the solidification process for cast components correctly, it is of essence to know how the material will actually behave. To produce sound castings, often of complex geometry, the industry relies on various simulation software for the prediction and avoidance of defects. Thermophysical properties, such as density, play an important part in these simulations.Previous measurements of how the volume of liquid grey iron changes with temperature has been made with a conventional dilatometer. Measurements have also been made in the austenitic range, then on iron-carbon-silicon alloys with a carbon content lower than 1.5 wt%. Based on these measurements the density variations during solidification were calculated. The scope for this paper is to model the volume changes during solidification with the control volume finite difference method, using data from the density measurements.

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Zhang, Jie, Kang Wen Li, Hai Wei Ye, Dong Qi Zhang e Peng Wei Wu. "Numerical Simulation of Solidification Process for Impeller Investment Casting". Applied Mechanics and Materials 80-81 (luglio 2011): 961–64. http://dx.doi.org/10.4028/www.scientific.net/amm.80-81.961.

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Investment casting method can fabricate the impeller slots with non-uniform thickness and distorted surface. The process of investment casting can be simulated by employing ProCAST software. The mesh of the casting was introduced in the article. The influence about the initial temperature of shell on the defects of the casting and the pouring temperature and the pouring speed on the effective stress of the casting was studied in this article. When the initial temperature of shell was 400°C,there was no defect in the casting. The pouring temperature of the casting, will produce a very strong influence on the effective stress. When the pouring temperature in this article was 800°C, the maximum effective stress of the casting was 108MPa.

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Klinkhammer, J., J. Thorborg, M. Bernhard, J. Winkler, C. Bernhard, R. Hanus e G. Tischler. "Hot tear prediction in large sized high alloyed turbine steel parts - experimental based calibration of mechanical data and model validation". IOP Conference Series: Materials Science and Engineering 1281, n. 1 (1 maggio 2023): 012068. http://dx.doi.org/10.1088/1757-899x/1281/1/012068.

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Abstract The main defects in heavy steel castings are related to hot tear formation during solidification. Depending on the steel grade, design, and local solidification conditions, it is possible to predict regions with higher risk of hot tear formation during the casting process. However, steels containing Boron show more complex crack and defect patterns compared to common steel casting alloys. The mechanisms behind the Boron induced hot tearing is investigated in this work to understand the influence of Boron enrichment during solidification and the influence on hot tearing. The experimental work includes the investigation of phase diagrams and the corresponding fractions of the solid and liquid phases depending on temperature using thermal analysis e.g. DSC and HT-LSCM. The hot tearing sensitivity and mechanical properties during solidification are obtained in the Submerged Split Chill Test, SSCT. In addition IMC-B 3-point bending tests are performed to determine high-temperature material properties in the solid state. The work is part of a research project where the final goal is to improve the hot tear predictions based on experimental work and carry out a benchmark simulation of a real sized casting and use it to show the agreement between the numerical results and extensive non-destructive testing from industrial observations.

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Chen, Tao, Dun Ming Liao e Jian Xin Zhou. "Numerical Simulation of Casting Thermal Stress and Deformation Based on Finite Difference Method". Materials Science Forum 762 (luglio 2013): 224–29. http://dx.doi.org/10.4028/www.scientific.net/msf.762.224.

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Thermal stress simulation is an important part in the numerical simulation of casting process. It provides engineers with insights into the evolution of displacement, strain and stress of castings in the solidification process. With thermal stress simulation, some defects of casting, i.e. hot tearing, cold cracking and large deformation can be predicted and the engineers are instructed to optimize and improve the casting process. Based on the finite difference method (FDM), this paper presents an integrated numerical method to simulate the thermal stress and deformation of casting in the solidification process. Practical examples show that the method is capable to predict stress distribution and deformation as well as the defects in the experiment.

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Yuan, Xun Feng, Rui Xia Hu, Ying Li, Ying Zhou, Lei Li e Lei Wei. "Simulation of Temperature Field in the Solidification Process of Cast". Advanced Materials Research 1088 (febbraio 2015): 834–37. http://dx.doi.org/10.4028/www.scientific.net/amr.1088.834.

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The direct difference method is used for solving the heat conduction equation, and simulate the solidification process of T-type cast. The effect of the thermal resistance at cast/mold on distribution of temperature and the solidification rate of corner region is studied. The results show that during the solidification process of T-type, the riser region first solidified, followed by the right half, finally the solidified part was around the corner. With the decrease of the thermal resistance at cast/mold, the temperature of the corner area decreased more quickly and the solidification rate increased. In the actual design process, the material with the good thermal conductivity should be selected for the cast mold to accelerate the solidification rate of the corner region, so the solidification rate of the corner and riser region tend towards harmony, which reducing the formation of various types of defects, and the quality and mechanical properties of the casts were improved.

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Monde, Aniket D., Anirban Bhattacharya e Prodyut R. Chakraborty. "Shrinkage induced flow and Free surface evolution during solidification of pure metal". E3S Web of Conferences 128 (2019): 06011. http://dx.doi.org/10.1051/e3sconf/201912806011.

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A numerical model is developed to study Shrinkage induced convection and free surface evolution caused by the density difference between the solid and liquid phases during the solidification of pure aluminium. For the analysis, a 2–D rectangular cavity field with aluminium melt undergoing solidification process is considered. Conservation of mass, momentum, and energy are formulated based on volume averaging technique and are solved using the SIMPLER algorithm. The free surface evolution is captured using the Volume of fluid (VOF) method. The proposed model focuses on predicting macro–scale shrinkage induced surface defects during the solidification process.

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Anjos, Vitor, Carlos A. Silva Ribeiro, Fátima Dias, Wolfgang Baumgart e João Cunha. "Literature Survey on Porosity and Microporosity in Cast Irons Related to Expansion and Gas Entrapment Phenomena". Key Engineering Materials 457 (dicembre 2010): 410–15. http://dx.doi.org/10.4028/www.scientific.net/kem.457.410.

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Macro and microporosity in castings are a problem that persists at many foundries, despite the use of advance simulation software’s. This fact indicates that other parameters rather then the casting shape/design or the “standard” metallurgical characteristics are not properly controlled, considered or modelled in the solidification simulation. In this paper we present the Phase I of a research project, which consists on a bibliographic review of the previous attempts to evaluate the relationship between solidification sequence and the measurement of expansion of molten metal during eutectic solidification and is relation to porosity and shrinkage defects.

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