scholarly journals Fluidity Investigation of Pure Al and Al-Si Alloys

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5372
Author(s):  
Toshio Haga ◽  
Shinjiro Imamura ◽  
Hiroshi Fuse
Keyword(s):  
Heat Transfer ◽  
Melt Spinning ◽  
Pure Aluminum ◽  
Injection Speed ◽  
Roll Casting ◽  
Die Cast ◽  
Flow Length ◽  
Cast Machine ◽  
Die Temperature ◽  
Si Content

Fluidity tests of pure aluminum 1070 and Al-Si alloys with Si contents of up to 25% were conducted using a die cast machine equipped with a spiral die. The effects of the channel gap, die temperature, and injection speed on the fluidity were investigated. When the channel gap was small (0.5 mm), the flow length of the 1070 was minimized, and the fluidity increased monotonically at a gradual rate with increasing Si content. In contrast, larger gaps yielded convex fluidity–Si content curves. Additionally, heating the die had less of an influence on the fluidity of the 1070 than on that of the Al-Si alloy. These results are discussed in the context of the peeling of the solidification layer from the die based on the thicknesses of foils and strips cast by melt spinning and roll casting, respectively. At lower Si contents, heat shrinkage was greater and the latent heat was lower. When the heat shrinkage was greater, the solidification layer began to peel earlier, and the heat transfer between the solidification layer and the die became smaller. As a result, the fluidity of the 1070 was greatest when the channel gap was 0.8 mm.

Effect of Casting Conditions on Fluidity of Aluminum Alloy in Die Casting

2020 ◽  
Author(s):  
Toshio Haga ◽  
Sinjiro Imamura ◽  
Hisaki Watari ◽  
Shinichi Nishida
Keyword(s):  
Heat Transfer ◽  
Aluminum Alloy ◽  
Latent Heat ◽  
Die Casting ◽  
Pure Aluminum ◽  
Semisolid State ◽  
Die Cast ◽  
Die Temperature ◽  
Si Content

Abstract The fluidity of pure aluminum and Al-Si alloys was investigated for casting thin products using a spiral die in die casting. An aluminum alloy with good fluidity can be die-cast into thin products. For a Si content of less than 6 mass%, the fluidity increased with decreasing Si content. For a Si content of greater than 6 mass%, the fluidity increased with increasing Si content. The fluidity was affected by latent heat, flowability in the semisolid state, and heat transfer between the die and metal. For pure aluminum, the latent heat is small and there is no semisolid state. However, pure aluminum has excellent fluidity because the heat transfer between the die and metal is small. For Al-25%Si, the latent heat is very large and flowability increases in the semisolid state. Therefore, the fluidity of Al-25%Si is high. Fluidity typically increases with increasing die temperature. The increase in fluidity due to an increase in die temperature for the pure aluminum is small compared with that for hypoeutectic Al-Si alloys. This means that the heat transfer between the pure aluminum and the die is smaller than that for hypoeutectic Al-Si alloys. Therefore, the influence of die temperature on the fluidity of the pure aluminum is small. It is estimated that the chill layer of the pure aluminum rapidly peels from the die, decreasing the heat transfer between the pure aluminum and the die.

Roll Casting and Die Casting of Si-Added Al-Mg Alloy

2020 ◽  
Vol 1007 ◽  
pp. 12-17
Author(s):  
Toshio Haga ◽  
Shinichiro Imamura ◽  
Hiroshi Fuse ◽  
Hisaki Watari ◽  
Shinichi Nishida
Keyword(s):  
High Speed ◽  
Die Casting ◽  
Sheet Forming ◽  
Mg Alloy ◽  
Tension Tests ◽  
Roll Casting ◽  
Cold Rolled ◽  
Twin Roll Caster ◽  
Si Content ◽  
Twin Roll

Si ranging from 0.2 mass% to 2.0 mass% was added to Al-5%Mg alloy (5182) and strip was cast by a vertical type high-speed twin-roll caster at a speed of 80 m/min. The as-cast strip was cold-rolled down to 1 mm thickness and annealed. The mechanical properties were investigated using cup tests and tension tests. The limiting draw ratio (LDR) of the 5182 alloy was 2.0 and the LDR became smaller as the Si content increased. When the Si content was 2.0 mass%, the LDR was 1.8, which shows that Si-added 5182 can be used for sheet forming, if the Si content is less than 2.0 mass%. The tensile strength and elongation were almost constant when the Si content was less than 1 mass%, but decreased at 2.0 mass% Si. However, the elongation was greater than 20% at 2.0 mass% Si. For die casting, 2.0 mass% Si was determined as the appropriate content from the results of the tension tests. When the Si content is in the range from 1.0 mass% to 2.0 mass%, then the Si added Al-5%Mg has the ability to be used for both die casting and sheet forming.

On some Characteristics of Microstructure and Defects in Die-Cast Magnesium Components

2005 ◽  
Vol 488-489 ◽  
pp. 283-286
Author(s):  
Hai Ping Cao
Keyword(s):  
Die Casting ◽  
Process Parameter ◽  
Casting Temperature ◽  
Injection Speed ◽  
Die Cast ◽  
Intensification Pressure ◽  
Segregation Band ◽  
Cast Magnesium ◽  
Spherical Crystals

Some commercial Mg components have been die cast at various casting conditions. The influence of process parameter settings on the microstructural features as well as one kind of defect called segregation band defect were investigated. It was found that more pre-solidified crystals were formed in the condition of lower casting temperature, and more broken dendrites and spherical crystals were formed under higher injection speed. The distribution characters of pre-solidified crystals were also presented and discussed in this paper. Concerning the band defects formed during die casting, a variety of segregation band morphologies as well as the influence of various casting conditions the performances on bands was presented. It was found out that intensification pressure has the strongest effect on the performance of segregation bands inside the castings.

High Speed Twin-Roll Casting of Al-Mg Alloys

2010 ◽  
Vol 154-155 ◽  
pp. 1544-1548 ◽  
Author(s):  
Kosuke Komeda ◽  
Ryoji Nakamura ◽  
Shinji Kumai
Keyword(s):  
Heat Transfer ◽  
Aluminum Alloy ◽  
High Speed ◽  
Aluminum Alloy 5182 ◽  
Roll Casting ◽  
Twin Roll Caster ◽  
Deep Drawing Test ◽  
Study Heat Transfer ◽  
Twin Roll ◽  
Steel Rolls

The disadvantages of the conventional twin-roll caster for aluminum alloy are low casting speeds and limited choices of alloys that are castable by this processing. It is known that strip casting of aluminum alloy 5182 is very difficult because of their wider freezing zones. The vertical-type high-speed twin-roll caster used in the present study was devised to overcome these disadvantages. Features of the high speed twin roll casters are as below. Mild steel rolls were used in order to increase the casting speed and to be made at a lower equipment cost. Roll coating is produced in casting of Al-Mg alloy. Therefore lubricant, that resists heat transfer, was not used in the present study. Heat transfer between melt and the roll was improved by hydrostatic pressure of the melt. Low superheat casting was carried out in order to improve microstructure of the strip. In the present study, effectiveness of a high-speed twin roll caster for recycling aluminum alloy was investigated. The effects of the high-speed twin roll caster on alleviating the deterioration of mechanical properties by impurities were investigated. Properties of the cast strip were investigated by metalography, a tension test, and a deep drawing test.

Application of Different Conductive Substrate Materials for Heat Transfer Enhancement in Cooling of Electronic Components

2014 ◽  
Vol 1082 ◽  
pp. 327-331
Author(s):  
Thiago Antonini Alves ◽  
Murilo A. Barbur ◽  
Felipe Baptista Nishida
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Transfer Enhancement ◽  
Forced Convection ◽  
Pure Aluminum ◽  
Rectangular Channel ◽  
Electronic Components ◽  
Transfer Enhancement ◽  
Cooling Process ◽  
Conductive Substrate

In this research, a study of the heat transfer enhancement in electronic components mounted in channels was conducted by using different materials in the conductive substrate. In this context, a numerical analysis was performed to investigate the cooling of 3D protruding heaters mounted on the bottom wall (substrate) of a horizontal rectangular channel using the ANSYS/FluentTM 15.0 software. Three different materials of the conductive substrate were analyzed, polymethyl methacrylate (PMMA), fiberglass reinforced epoxy laminate (FR4), and pure aluminum (Al). Uniform heat generation rate was considered for the protruding heaters and the cooling process happened through a steady laminar airflow, with constant properties. The fluid flow velocity and temperature profiles were uniform at the channel entrance. For the adiabatic substrate, the cooling process occurred exclusively by forced convection. For the conductive substrate, the cooling process was characterized by conjugate forced convection-conduction heat transfer through two mechanisms; one directly between the heaters surfaces and the flow by forced convection, and the other through conduction at the interfaces heater-substrate in addition to forced convection from the substrate to the fluid flow at the substrate surface. The governing equations and boundary conditions were numerically solved through a coupled procedure using the Control Volumes Method in a single domain comprising the solid and fluid regions. Commonly used properties in cooling of electronics components mounted in a PCB and typical geometry dimensions were utilized in the results acquisition. Some examples were presented, indicating the dependence of the substrate thermal conductivity related to the Reynolds number on the heat transfer enhancement. Thus, resulting in a lower work temperature at the electronic components.

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