• Transactions of Materials Processing
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• v.30 no.5
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• pp.219-225
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• 2021

When extruding Al6061 alloys, deformation energy is deposited inside the extruded alloy depending on the deformation and the temperature of extrusion. This creates a Peripheral Coarse Grain (PCG) on the surface, where relatively more deformation energy. of the extruded alloy has been accumulated. Furthermore, since the deformation of materials continues while the materials recrystallize, it is important to examine the effect of deformation energy on dynamic recrystallization in the process of extruding Al alloys along with their microstructure. Prior studies explain the theory behind PCG growth though quantitative analysis on PCG growth of Al alloys during extrusion processes has not yet been addressed. This study aims to measure the generated PCG thickness which determines the correlation between extrusion outlet temperature and its effect on mechanical properties. Surface structure observations were performed using Optical Microscope (OM) and mechanical properties were evaluated through tensile strength and hardness measurement. Throughout this study, we endevoured to find the optimum condition of extrusion exit temperature of Al6061 and confirmed improved d reliability. This study describes the effect of the complex process variables such as exit temperature on the thickness of PCG layer for the Al6061 alloy using the 200 tons extrusion press. We therefore, discovered that the PCG layer thickness was 117 ㎛ at temperatures between 460 ℃ to 520 ℃.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.231-234
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• 1998

This study presents steady-state finite element analysis of three-dimensional hot extrusion of sections through square dies. The objective of this study is to develop a steady-state finite element method for hot extrusion through square dies, and to provide theoretical basis for the optimal die design and process control in the extrusion technology. In the present work, steady-state assumption is applied to both analyses of deformation and temperature. The analysis of temperature distribution includes heat transfer. Convection like element is adopted for the heat transfer analysis between billet and container, and also billet and die. Distributions of temperature, effective strain rate, velocity and mean stress are discussed to design extrusion die effectively.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.39-45
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• 2011

In this study, the heat flow of the plant scale aluminum extrusion process was investigated to establish optimum continuous heat treatment conditions. During the extrusion of 6061 aluminum alloy, processing parameters such as the extrusion pressure, speed and temperature histories of billets were logged as a function of time. The surface temperature of the billets increased at constant ram speed, while it decreased with decreases of the ram speed. In order to maintain the billet temperature within a solutionizing temperature range prior to the succeeding water quenching step, the ram speed or the temperature of the blower should be controlled. The temperature histories of the billets during the extrusion and hot air blowing processes were successfully simulated by using the velocity boundary model in ANSYS CFX. The methodology to design an optimum process by using a commercial simulation program is described in this study on the basis of the metallurgical validation results of the microstructural observation of the extrudates. The developed model allowed the advantages of taking into account the motion of the extrudate coupled with the temperature change based on empirical data. Calculations were made for the extrudate passing through the isothermal chamber maintained at appropriate temperature. It was confirmed that the continuous heat treatment system is beneficial to the productivity enhancement of the commercial aluminum extrusion industry.

• Applied Biological Chemistry
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• v.25 no.3
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• pp.119-125
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• 1982

Using piston type extruder, barley flour was extruded at various processing conditions, The used variables were three shear rates (apparent shear rate 118, 534, $1169sec^{-1}$), four extrusion temperatures(90, 120, 150, $180^{\circ}C$) and three moisture contents (15, 25, 35%). The rheological properties and the extrudate quality were monitored in extrusion. Barley flour showed pseudoplastic behavior having average power law index 0.28 in used shear rate range. When viewed from general appearance, die swell, density, water uptake, rehydration swell and gelatinization degree of extrudate, $25{\sim}35%$ moisture and $120^{\circ}C$ temperature was suitable processing condition for noodle-like product, and 25% moisture and $150^{\circ}C$ temperature was good for snack or flake product. Moisture content of the extrudate can be pretty well estimated from energy balance at higher temperature and higher moisture content.

• Korean Journal of Food Science and Technology
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• v.22 no.6
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• pp.651-658
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• 1990

Starch phosphates were prepared by dry heating, gelatinizing method and extrusion process using sodium tripolyphosphote (STPP) as a substitution reagent and their physicochemical properities were compared. In the preparation of starch phosphate by dry heating method(DSP), the effect of reaction temperature was the most significant to the DS(Degree of substitution). In the phosphorylation reaction with gelatinized starch(GSP), the substitution ratio was increased with increasing the reaction temperature, but the increase was insignificant above $85^{\circ}C$. By extrusion with the corn starch containing 2.0% STPP at various moisture contents of 20, 25 and 30%, the DS values of extrudate(WESP) were within the range of between 0.0066 and 0.0083. The starch phosphate(DSP) products showed lowering the gelatinization temperature, increasing the clarity of the starch paste. However, WESP showed higher gelatinization temperature than that of raw starch. The starch phosphate prepared by extrusion process showed lower apparent viscosity of paste than that of the DSP at same condition. All of starch phosphates showed reducing the tendency of the paste retrogradation.

• Food Science and Biotechnology
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• v.14 no.3
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• pp.363-367
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• 2005

Although widely applied in the food industry, extrusion cooking has not been applied to the traditional red ginseng process for steaming and drying ginseng. We therefore investigated the change in the effective components in red ginseng (total saponins, ginsenosides and maltol) from extruded raw ginseng. The variables were the drying temperature of the sliced raw ginseng (80 and $90^{\circ}C$) before the extrusion process and the moisture content (15 and 22%, w.b.) during the extrusion process. Ginsenosides Rg1 and Rg2 were detected in dried ginseng at $80^{\circ}C$, but ginsenoside Rg3, which was contained in red ginseng, was not detected. On the other hand, ginsenosides Rg1, Rg2 and Rg3 were detected in extruded ginseng at moisture contents of 15 and 22%. Total ginsenosides were highest at $90^{\circ}C$ drying temperature and 22% moisture content for the extrusion process.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.311-320
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• 2009

Most advanced countries are researching to apply light weight materials far rolling stock because weight reduction for railway body derives cost-saving, energy-saving, and high-speed. Likewise, current Korea rolling stock field makes arduous effects of weight-reduction, miniaturization, and high-efficiency to achieve a high-speed railway. Aluminum becomes suitable material for these projects because it is much lighter than steel or stainless. Manufacturing the railway car body by using the Aluminum is increasing because Aluminum is not bringing the corrosion by unique oxidation-passivate. Aluminum extrusion profile far railway body requires a high mechanical property, accurate shape dimension, and stable quality because the railway body is composed with many different kinds of extruded profiles. Therefore, it is necessary to research about Aluminum precision-extrusion technology to maintain exit temperature and die load. The goal of this project is applying the Aluminum extrusion profile to next-generation railway car body by developing the Aluminum extrusion profile according to precision-extrusion technology which may maintain isothermal exit temperature.

• Transactions of Materials Processing
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• v.27 no.6
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• pp.379-385
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• 2018

This study investigated the effect of extrusion conditions on microstructures and mechanical properties of AM80 magnesium alloys. The billets of magnesium alloy used for hot extrusion were prepared by permanent mold casting method, and its extrusion was hot direct extrusion with different extrusion conditions. The results of microstructural analysis showed that the main phases in the as-casted alloys were ${\alpha}-Mg$, ${\beta}-Mg_{17}Al_{12}$, and lamella $Mg_{17}Al_{12}$. Hot extrusion results, The tensile strength of the most soundly manufactured extruded bars (extrusion temp: $350^{\circ}C$, extrusion ratio: 27:1, ram speed: 2mm/s) was approximately 327MPa at room temperature. The increase in the mechanical properties of hot-extruded alloys was as a result of grain refinement by dynamical recrystallization during hot extrusion.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.5
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• pp.783-787
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• 1999

To study the effects of different extrusion conditions of barley on growth performance, nutrient digestibility and nutrient excretion in feces, a total of 150 growing pigs ($Landrace{\times}Duroc{\times}Large$ White; average 24.4 kg body weight) were allotted to five treatments, in a completely randomized block design. The experimental diets were based on corn-soybean and 30% of barley was included in each diet; barley was the only extruded ingredient. The treatments were 1) no extrusion (Control); 2) extrusion at $100^{\circ}C$ without preconditioning (ENLT); 3) extrusion at $150^{\circ}C$ without preconditioning (ENHT); 4) extrusion at $100^{\circ}C$ with preconditioning (ECLT); 5) extrusion at $150^{\circ}C$ with preconditioning (ECHT). Temperature in the barrel was controlled within ${\pm}5^{\circ}C$ by feed rate with the addition of water at the rate of $3{\ell}\;per\;min$. in the extruder for each treatment. For the 6 week experimental period, extrusion of barley improved the average daily gain (ADG) and digestibilities of dry matter, crude protein and gross energy in growing pigs. As compared to control, significant improvements in ADG (p<0.05) were shown in the groups of feeding extruded barley at high temperature (ENHT and ECHT). There were also significant differences in the digestibilities of DM, CP and P between extrusion temperatures. Barley extruded at high temperature gave better digestibilities of DM, CP and GE than barley extruded at low temperature. Extruded barley diet groups showed significantly (p<0.05) lower excretions of DM, nitrogen (N) and P per kg gain as compared to the ground barley group. DM, N and P excretion per kg gain were also significantly lower in pigs fed barley extruded at $150^{\circ}C$ than at $100^{\circ}C$. In conclusion, extrusion considerably improved the nutritive value of barley and it appeared that temperature is the most important variable.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.812-816
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• 2007

To overcome the problem of ginseng's earthy smell in the manufacture of ginseng wine, we used dried ginseng powder that was extrusion-cooked at $125-168^{\circ}C$ in the wine making process. By using a ginseng powder that was extrusion-cooked at higher temperatures, fermentation by Maillard reaction products (MRPs) was delayed, and the acidic pH that results from extrusion cooking was improved. At $15^{\circ}C$ with glucose instead of sucrose, an addition of 0.5%(w/v) diammonium phosphate (DAP) to the $125^{\circ}C$ extrusion-cooked ginseng powder reduced the primary fermentation time to 11 days versus 33 days without DAP. In the absence of DAP, by increasing the fermentation temperature from 15 to $30^{\circ}C$, increasing the starter yeast inoculate from 0.02 to 1 %, and by increasing the amount of ginseng extrudate from 1 to 2%, fermentation time was effectively reduced more than 10-fold. The results of this study may provide information for the alcohol fermentation of materials containing MRPs as well as for poor nitrogen sources.