The Experts below are selected from a list of 2211 Experts worldwide ranked by ideXlab platform
Yoshihiko Hangai - One of the best experts on this subject based on the ideXlab platform.
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foaming behavior of blowing and stabilization agent free aluminum foam precursor during spot friction stir welding
Journal of Materials Processing Technology, 2019Co-Authors: Yoshihiko Hangai, Keisuke Takada, Hidetoshi Fujii, Yasuhiro Aoki, Takao UtsunomiyaAbstract:Abstract ADC12 Die-casting precursors containing many gas pores were fabricated by the friction stir welding (FSW) route and were foamed by the FSW foaming process only using the friction heat during the indentation of the tool used for spot FSW. ADC12 precursors can be foamed by the friction heat generated during spot FSW without using TiH2 as a blowing agent. ADC12 foams can be obtained without using Al2O3 as a stabilization agent. This is considered to be due to impurities contained in the ADC12 Die-Castings. ADC12 foams with Al2O3 exhibited a larger expansion ratio than those without Al2O3. ADC12 foams with Al2O3 had significantly finer pores than those without Al2O3. The pore diameters of the ADC12 foams with Al2O3 were approximately half of those of the foams without Al2O3. This is considered to be due to the higher viscosity of the ADC12 substrate containing Al2O3.
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Aluminum Foam-Filled Steel Tube Fabricated from Aluminum Burrs of Die-Castings by Friction Stir Back Extrusion
MDPI AG, 2019Co-Authors: Yoshihiko Hangai, Ryusei Kobayashi, Ryosuke Suzuki, Masaaki Matsubara, Nobuhiro YoshikawaAbstract:A mixture of Al burrs of Al high-pressure Die-Castings and a blowing agent powder was used to fabricate Al foam-filled steel tubes by friction stir back extrusion (FSBE). It was shown that the mixture can be sufficiently consolidated to form an Al precursor that is coated on the inner surface of a steel tube by the plastic flow generated during FSBE. Namely, a precursor coated steel tube can be fabricated from Al burrs by FSBE. By heat treatment of the precursor coated steel tube, an Al foam-filled steel tube can be fabricated. Al foam was sufficiently filled in the steel tube, and the porosity was almost homogeneously distributed in the entire sample. In compression tests of the samples, the Al foam-filled steel tube fabricated from Al burrs exhibited similar compression properties to an Al foam-filled steel tube fabricated from the bulk Al precursor. Consequently, it was shown that an Al foam-filled steel tube cost-effectively fabricated from Al burrs by FSBE compares favorably with an Al foam-filled steel tube fabricated from the bulk Al precursor
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tensile properties and fracture behavior of aluminum alloy foam fabricated from Die Castings without using blowing agent by friction stir processing route
Materials, 2014Co-Authors: Yoshihiko Hangai, Takao Utsunomiya, Soichiro Kitahara, Hiroto Kamada, Osamu Kuwazuru, Nobuhiro YoshikawaAbstract:Al foam has been used in a wide range of applications owing to its light weight, high energy absorption and high sound insulation. One of the promising processes for fabricating Al foam involves the use of a foamable precursor. In this study, ADC12 Al foams with porosities of 67%–78% were fabricated from Al alloy Die Castings without using a blowing agent by the friction stir processing route. The pore structure and tensile properties of the ADC12 foams were investigated and compared with those of commercially available ALPORAS. From X-ray computed tomography (X-ray CT) observations of the pore structure of ADC12 foams, it was found that they have smaller pores with a narrower distribution than those in ALPORAS. Tensile tests on the ADC12 foams indicated that as their porosity increased, the tensile strength and tensile strain decreased, with strong relation between the porosity, tensile strength, and tensile strain. ADC12 foams exhibited brittle fracture, whereas ALPORAS exhibited ductile fracture, which is due to the nature of the Al alloy used as the base material of the foams. By image-based finite element (FE) analysis using X-ray CT images corresponding to the tensile tests on ADC12 foams, it was shown that the fracture path of ADC12 foams observed in tensile tests and the regions of high stress obtained from FE analysis correspond to each other. Therefore, it is considered that the fracture behavior of ADC12 foams in relation to their pore structure distribution can be investigated by image-based FE analysis.
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effects of porosity and pore structure on compression properties of blowing agent free aluminum foams fabricated from aluminum alloy Die Castings
Materials Transactions, 2012Co-Authors: Yoshihiko Hangai, Hiroki Kato, Takao Utsunomiya, Soichiro Kitahara, Osamu Kuwazuru, Nobuhiro YoshikawaAbstract:Aluminum foam was fabricated without the use of a blowing agent by a friction stir processing route using ADC12 aluminum alloy Die Castings, which contain a large number of gas pores. In this study, ADC12 foams with a porosity of 5077% were successfully fabricated, and the pore structures and compression properties of the obtained ADC12 foams were investigated. The ADC12 foams had smaller pores than commercially available aluminum foam. Moreover, the pore size of the ADC12 foams was almost the same regardless of the porosity. According to the results of compression tests, the plateau stress and energy absorption tend to decrease with increasing porosity. Commercially available aluminum foam exhibited higher energy absorption at a low compression stress, whereas the ADC12 foams exhibited higher energy absorption at a high compression stress. Also, the ADC12 foams with higher porosity exhibited higher energy absorption per unit mass, regardless of the compression stress. In contrast, the energy absorption per unit volume was greatest for the low-porosity ADC12 foam at a low compression stress but greatest for the high-porosity foam at a high compression stress. [doi:10.2320/matertrans.M2012125]
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fabrication of functionally graded aluminum foam using aluminum alloy Die Castings by friction stir processing
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: Yoshihiko Hangai, Takao Utsunomiya, Kazuya Takahashi, Soichiro Kitahara, Osamu Kuwazuru, Nobuhiro YoshikawaAbstract:Abstract Functionally graded aluminum (FG) foam with varying pore structure was fabricated by utilizing friction stir processing. Die Castings containing a large amount of gas were used as the starting material. The obtained FG foam had two different deformation stages and two plateau regions with a seamless bonding interface.
Takao Utsunomiya - One of the best experts on this subject based on the ideXlab platform.
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foaming behavior of blowing and stabilization agent free aluminum foam precursor during spot friction stir welding
Journal of Materials Processing Technology, 2019Co-Authors: Yoshihiko Hangai, Keisuke Takada, Hidetoshi Fujii, Yasuhiro Aoki, Takao UtsunomiyaAbstract:Abstract ADC12 Die-casting precursors containing many gas pores were fabricated by the friction stir welding (FSW) route and were foamed by the FSW foaming process only using the friction heat during the indentation of the tool used for spot FSW. ADC12 precursors can be foamed by the friction heat generated during spot FSW without using TiH2 as a blowing agent. ADC12 foams can be obtained without using Al2O3 as a stabilization agent. This is considered to be due to impurities contained in the ADC12 Die-Castings. ADC12 foams with Al2O3 exhibited a larger expansion ratio than those without Al2O3. ADC12 foams with Al2O3 had significantly finer pores than those without Al2O3. The pore diameters of the ADC12 foams with Al2O3 were approximately half of those of the foams without Al2O3. This is considered to be due to the higher viscosity of the ADC12 substrate containing Al2O3.
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tensile properties and fracture behavior of aluminum alloy foam fabricated from Die Castings without using blowing agent by friction stir processing route
Materials, 2014Co-Authors: Yoshihiko Hangai, Takao Utsunomiya, Soichiro Kitahara, Hiroto Kamada, Osamu Kuwazuru, Nobuhiro YoshikawaAbstract:Al foam has been used in a wide range of applications owing to its light weight, high energy absorption and high sound insulation. One of the promising processes for fabricating Al foam involves the use of a foamable precursor. In this study, ADC12 Al foams with porosities of 67%–78% were fabricated from Al alloy Die Castings without using a blowing agent by the friction stir processing route. The pore structure and tensile properties of the ADC12 foams were investigated and compared with those of commercially available ALPORAS. From X-ray computed tomography (X-ray CT) observations of the pore structure of ADC12 foams, it was found that they have smaller pores with a narrower distribution than those in ALPORAS. Tensile tests on the ADC12 foams indicated that as their porosity increased, the tensile strength and tensile strain decreased, with strong relation between the porosity, tensile strength, and tensile strain. ADC12 foams exhibited brittle fracture, whereas ALPORAS exhibited ductile fracture, which is due to the nature of the Al alloy used as the base material of the foams. By image-based finite element (FE) analysis using X-ray CT images corresponding to the tensile tests on ADC12 foams, it was shown that the fracture path of ADC12 foams observed in tensile tests and the regions of high stress obtained from FE analysis correspond to each other. Therefore, it is considered that the fracture behavior of ADC12 foams in relation to their pore structure distribution can be investigated by image-based FE analysis.
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effects of porosity and pore structure on compression properties of blowing agent free aluminum foams fabricated from aluminum alloy Die Castings
Materials Transactions, 2012Co-Authors: Yoshihiko Hangai, Hiroki Kato, Takao Utsunomiya, Soichiro Kitahara, Osamu Kuwazuru, Nobuhiro YoshikawaAbstract:Aluminum foam was fabricated without the use of a blowing agent by a friction stir processing route using ADC12 aluminum alloy Die Castings, which contain a large number of gas pores. In this study, ADC12 foams with a porosity of 5077% were successfully fabricated, and the pore structures and compression properties of the obtained ADC12 foams were investigated. The ADC12 foams had smaller pores than commercially available aluminum foam. Moreover, the pore size of the ADC12 foams was almost the same regardless of the porosity. According to the results of compression tests, the plateau stress and energy absorption tend to decrease with increasing porosity. Commercially available aluminum foam exhibited higher energy absorption at a low compression stress, whereas the ADC12 foams exhibited higher energy absorption at a high compression stress. Also, the ADC12 foams with higher porosity exhibited higher energy absorption per unit mass, regardless of the compression stress. In contrast, the energy absorption per unit volume was greatest for the low-porosity ADC12 foam at a low compression stress but greatest for the high-porosity foam at a high compression stress. [doi:10.2320/matertrans.M2012125]
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fabrication of functionally graded aluminum foam using aluminum alloy Die Castings by friction stir processing
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: Yoshihiko Hangai, Takao Utsunomiya, Kazuya Takahashi, Soichiro Kitahara, Osamu Kuwazuru, Nobuhiro YoshikawaAbstract:Abstract Functionally graded aluminum (FG) foam with varying pore structure was fabricated by utilizing friction stir processing. Die Castings containing a large amount of gas were used as the starting material. The obtained FG foam had two different deformation stages and two plateau regions with a seamless bonding interface.
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effects of amounts of blowing agent and contained gases on porosity and pore structure of porous aluminum fabricated from aluminum alloy Die casting by friction stir processing route
Materials Transactions, 2011Co-Authors: Takao Utsunomiya, Kazuya Takahashi, Yoshihiko Hangai, Soichiro KitaharaAbstract:Porous aluminum is expected to be applied as a multifunctional material in various industrial fields because of its light weight and high energy absorption. When aluminum alloy Die Castings are used as a starting material in the fabrication of porous aluminum, it can be expected that, by effectively using the gases intrinsically contained in the Die casting to generate pores, porous aluminum can be fabricated by adding a small amount of blowing agent. In this study, while systematically varying the amount of blowing agent from 0 to 1.4 mass% that is added to ADC12 aluminum alloy Die Castings containing three different amounts of gases, porous aluminum is fabricated by the FSP (friction stir processing) route precursor method. Titanium(II) hydride powder is used as the blowing agent. The variations of porosity and pore structure with the amount of added blowing agent are investigated for each amount of gases contained in the Die Castings. On the basis of the results, it is shown that, by using a blowing agent of approximately 0.6 mass%, ADC12 porous aluminum with high porosity can be fabricated regardless of the amount of gases contained in the Die casting.
Shoumei Xiong - One of the best experts on this subject based on the ideXlab platform.
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skin layer of a380 aluminium alloy Die Castings and its blistering during solution treatment
Journal of Materials Science & Technology, 2019Co-Authors: Zihao Yuan, Shoumei XiongAbstract:Abstract Skin layer is a characteristic microstructure of aluminium Die Castings, which would effect the surface blistering during solution treatment. In this study, the microstructures of skin layer were investigated by the methods of optical microscope (OM), scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). High resolution X-ray CT was used to compare the skin layer with normal surface before and after solution treatment. With the aid of computational fluid dynamics (CFD), the formation mechanism of the skin layer was discussed based on microstructure distribution, solute segregation, porosity distribution and surface blistering. The results suggested that the skin layer is related to a succession of complex processes before the filling process finished. Pore clusters or laminar defects would be formed in skin layers during solution treatment and cause severe surface blistering.
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effects of process parameters on morphology and distribution of externally solidified crystals in microstructure of magnesium alloy Die Castings
China Foundry, 2018Co-Authors: Zhipeng Guo, Shoumei XiongAbstract:During the cold-chamber high pressure Die casting (HPDC) process, samples were produced to investigate the microstructure characteristics of AM60B magnesium alloy. Special attention was paid to the effects of process parameters on the morphology and distribution of externally solidified crystals (ESCs) in the microstructure of magnesium alloy Die Castings, such as slow shot phase plunger velocity, delay time of pouring and fast shot phase plunger velocity. On the basis of metallographic observation and quantitative statistics, it is concluded that a lower slow shot phase plunger velocity and a longer delay time of pouring both lead to an increment of the size and percentage of the ESCs, due to the fact that a longer holding time of the melt in the shot sleeve will cause a more severe loss of the superheat. The impingement of the melt flow on the ESCs is more intensive with a higher fast shot phase plunger velocity, in such case the ESCs reveal a more granular and roundish morphology and are dispersed throughout the cross section of the Castings. Based on analysis of the filling and solidification processes of the melt during the HPDC process, reasonable explanations were proposed in terms of the nucleation, growth, remelting and fragmentation of the ESCs to interpret the effects of process parameters on the morphology and distribution of the ESCs in the microstructure of magnesium alloy Die Castings.
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microstructure characteristics of the eutectics of Die cast am60b magnesium alloy
Journal of Materials Science & Technology, 2011Co-Authors: Shoumei XiongAbstract:Under the cold-chamber high pressure Die casting (HPDC) process, samples were produced with AM60B magnesium alloy to investigate the microstructure characteristics of the eutectics, especially focusing on the constitution, morphology and distribution of the eutectics over cross section of the Castings. Attentions were also paid to study the efiect of heat treatment on the eutectics in the Die Castings. Based on experimental analysis using optical microscopy (OM), X-ray difiraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), it was determined that fully divorced eutectics consisting of fi-Mg and fl-Mg17Al12 appeared at the grain boundary of the primary fi-Mg in the as-cast microstructure. Islands and networks of fl-Mg17Al12 phase were observed in the central region of the Castings, while the fl-Mg17Al12 phase revealed a more dispersed and granular morphology on the surface layer. The two phases ratio fl/fi in the central region of the Castings was approximately 10%, which was higher than that on the surface layer. Besides, the defect bands contained a higher percentage of the eutectics than the adjacent regions. After aging treatment (T6), only fi-Mg phase was detected by XRD in the AM60B magnesium alloy, though a small amount of precipitated fl-Mg17Al12 phase was observed at the grain boundary. In contrast to the microstructure of Die cast AZ91D magnesium alloy under the same T6 heat treatment, no discontinuous precipitation of the fl-Mg17Al12 phase was observed in AM60B magnesium alloy Die Castings.
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study on pressure variations in the mold of magnesium alloy Die Castings
Key Engineering Materials, 2007Co-Authors: Yan Gai Liu, Zhaohui Huang, Hao Ding, Minghao Fang, Shoumei XiongAbstract:High pressure Die casting is the most common method in making magnesium alloys for both auto parts and 3C products. Pressure variations in the mold during mold filling and solidification process have direct influences on the quality and properties of Die Castings. In this paper, a cylinder head cover was produced to experimentally study pressure variations in the mold during magnesium alloy Die-casting process in real time for the first time. Pressure varies at different positions in the mold during Die casting process. This study indicates that mold filling and solidification process of magnesium alloy Die Castings can be described by pressure curves obtained by pressure measurement at different test positions in the cavity in real time.
Nobuhiro Yoshikawa - One of the best experts on this subject based on the ideXlab platform.
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Aluminum Foam-Filled Steel Tube Fabricated from Aluminum Burrs of Die-Castings by Friction Stir Back Extrusion
MDPI AG, 2019Co-Authors: Yoshihiko Hangai, Ryusei Kobayashi, Ryosuke Suzuki, Masaaki Matsubara, Nobuhiro YoshikawaAbstract:A mixture of Al burrs of Al high-pressure Die-Castings and a blowing agent powder was used to fabricate Al foam-filled steel tubes by friction stir back extrusion (FSBE). It was shown that the mixture can be sufficiently consolidated to form an Al precursor that is coated on the inner surface of a steel tube by the plastic flow generated during FSBE. Namely, a precursor coated steel tube can be fabricated from Al burrs by FSBE. By heat treatment of the precursor coated steel tube, an Al foam-filled steel tube can be fabricated. Al foam was sufficiently filled in the steel tube, and the porosity was almost homogeneously distributed in the entire sample. In compression tests of the samples, the Al foam-filled steel tube fabricated from Al burrs exhibited similar compression properties to an Al foam-filled steel tube fabricated from the bulk Al precursor. Consequently, it was shown that an Al foam-filled steel tube cost-effectively fabricated from Al burrs by FSBE compares favorably with an Al foam-filled steel tube fabricated from the bulk Al precursor
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tensile properties and fracture behavior of aluminum alloy foam fabricated from Die Castings without using blowing agent by friction stir processing route
Materials, 2014Co-Authors: Yoshihiko Hangai, Takao Utsunomiya, Soichiro Kitahara, Hiroto Kamada, Osamu Kuwazuru, Nobuhiro YoshikawaAbstract:Al foam has been used in a wide range of applications owing to its light weight, high energy absorption and high sound insulation. One of the promising processes for fabricating Al foam involves the use of a foamable precursor. In this study, ADC12 Al foams with porosities of 67%–78% were fabricated from Al alloy Die Castings without using a blowing agent by the friction stir processing route. The pore structure and tensile properties of the ADC12 foams were investigated and compared with those of commercially available ALPORAS. From X-ray computed tomography (X-ray CT) observations of the pore structure of ADC12 foams, it was found that they have smaller pores with a narrower distribution than those in ALPORAS. Tensile tests on the ADC12 foams indicated that as their porosity increased, the tensile strength and tensile strain decreased, with strong relation between the porosity, tensile strength, and tensile strain. ADC12 foams exhibited brittle fracture, whereas ALPORAS exhibited ductile fracture, which is due to the nature of the Al alloy used as the base material of the foams. By image-based finite element (FE) analysis using X-ray CT images corresponding to the tensile tests on ADC12 foams, it was shown that the fracture path of ADC12 foams observed in tensile tests and the regions of high stress obtained from FE analysis correspond to each other. Therefore, it is considered that the fracture behavior of ADC12 foams in relation to their pore structure distribution can be investigated by image-based FE analysis.
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effects of porosity and pore structure on compression properties of blowing agent free aluminum foams fabricated from aluminum alloy Die Castings
Materials Transactions, 2012Co-Authors: Yoshihiko Hangai, Hiroki Kato, Takao Utsunomiya, Soichiro Kitahara, Osamu Kuwazuru, Nobuhiro YoshikawaAbstract:Aluminum foam was fabricated without the use of a blowing agent by a friction stir processing route using ADC12 aluminum alloy Die Castings, which contain a large number of gas pores. In this study, ADC12 foams with a porosity of 5077% were successfully fabricated, and the pore structures and compression properties of the obtained ADC12 foams were investigated. The ADC12 foams had smaller pores than commercially available aluminum foam. Moreover, the pore size of the ADC12 foams was almost the same regardless of the porosity. According to the results of compression tests, the plateau stress and energy absorption tend to decrease with increasing porosity. Commercially available aluminum foam exhibited higher energy absorption at a low compression stress, whereas the ADC12 foams exhibited higher energy absorption at a high compression stress. Also, the ADC12 foams with higher porosity exhibited higher energy absorption per unit mass, regardless of the compression stress. In contrast, the energy absorption per unit volume was greatest for the low-porosity ADC12 foam at a low compression stress but greatest for the high-porosity foam at a high compression stress. [doi:10.2320/matertrans.M2012125]
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fabrication of functionally graded aluminum foam using aluminum alloy Die Castings by friction stir processing
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: Yoshihiko Hangai, Takao Utsunomiya, Kazuya Takahashi, Soichiro Kitahara, Osamu Kuwazuru, Nobuhiro YoshikawaAbstract:Abstract Functionally graded aluminum (FG) foam with varying pore structure was fabricated by utilizing friction stir processing. Die Castings containing a large amount of gas were used as the starting material. The obtained FG foam had two different deformation stages and two plateau regions with a seamless bonding interface.
V D Tsoukalas - One of the best experts on this subject based on the ideXlab platform.
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optimization of porosity formation in alsi9cu3 pressure Die Castings using genetic algorithm analysis
Materials & Design, 2008Co-Authors: V D TsoukalasAbstract:Abstract In this investigation, an effective approach based on multivariable linear regression (MVLR) and genetic algorithm (GA) methods has been developed to determine the optimum conditions leading to minimum porosity in AlSi9Cu3 aluminium alloy Die Castings. Experiments were conducted by varying holding furnace temperature, Die temperature, plunger velocities in the first and second stage, and multiplied pressure in the third stage using L27 orthogonal array of Taguchi method. The experimental results from the orthogonal array were used as the training data for the MVLR model to map the relationship between process parameters and porosity formation of the Die cast parts. With the fitness function based on this model, genetic algorithms were used for the process conditions optimization. By comparing the predicted values with the experimental data, it was demonstrated that the proposed model is a useful and efficient method to find the optimal process conditions in pressure Die casting associated with the minimum porosity percent.
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optimization of porosity formation in alsi9cu3 pressure Die Castings using genetic algorithm analysis
Materials & Design, 2008Co-Authors: V D TsoukalasAbstract:In this investigation, an effective approach based on multivariable linear regression (MVLR) and genetic algorithm (GA) methods has been developed to determine the optimum conditions leading to minimum porosity in AlSi9Cu3 aluminium alloy Die Castings. Experiments were conducted by varying holding furnace temperature, Die temperature, plunger velocities in the first and second stage, and multiplied pressure in the third stage using L27 orthogonal array of Taguchi method. The experimental results from the orthogonal array were used as the training data for the MVLR model to map the relationship between process parameters and porosity formation of the Die cast parts. With the fitness function based on this model, genetic algorithms were used for the process conditions optimization. By comparing the predicted values with the experimental data, it was demonstrated that the proposed model is a useful and efficient method to find the optimal process conditions in pressure Die casting associated with the minimum porosity percent.