Mold Filling Simulation of Semi-Solid Magnesium Alloys

2008 ◽  
pp. 231-236
Author(s):  
Florin Ilinca ◽  
Jean François Hétu ◽  
Frank Ajersch ◽  
Jean François Moisan
Keyword(s):  
Magnesium Alloys ◽  
Mold Filling ◽  
Semi Solid ◽  
Filling Simulation

Prediction of Phase Segregation During Mold Filling of Semi-Solid Slurries

1999 ◽  
Author(s):  
Mahmut D. Mat ◽  
Olusegun J. Ilegbusi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Solid Fraction ◽  
Transfer Rate ◽  
Phase Segregation ◽  
Mold Filling ◽  
Semisolid Slurry ◽  
Processing Parameter ◽  
Inlet Velocity ◽  
Semi Solid

Abstract Phase segregation during the mold filling of semisolid slurry (Sn-15%Pb) is numerically investigated under non-isothermal conditions. The effects of operating parameters on the phase segregation including inlet velocity, initial solid fraction, heat transfer rate, mold geometry are considered. The semi-solid slurry is considered a non-Newtonian fluid below a critical solid fraction (fcr) and a viscoplastic medium saturated with liquid phase above the critical solid fraction. A group of particles are introduced at the mold inlet and phase segregation is studied by following the trajectories of these particles. The sharp property change at the slurry air interface is resolved with Van Leer numerical method. It is found that phase segregation is significantly affected by processing parameter. The segregation decreases with high inlet velocity, low heat transfer rate from the mold wall and cylindrical mold geometry.

scholarly journals Cyclic Deformation of Semi-solid Processed Magnesium Alloys

2021 ◽  
Author(s):  
Himesh Patel
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloys ◽  
Strain Amplitude ◽  
Cyclic Deformation ◽  
Weight Ratio ◽  
Aging Treatment ◽  
Strain Ratio ◽  
Plastic Strain Amplitude ◽  
Total Strain Amplitude ◽  
Semi Solid

To improve fuel economy and reduce greenhouse gas emissions, magnesium alloys are being considered for automotive and aerospace applications because of their high strength-to-weight ratio. The objective of this thesis was to study monotonic and cyclic deformation behavior of two semi-solid processed (thixomolded) magnesium alloys, AZ91D and AM60B. The fatigue life of these thixomolded alloys was observed to be higher than that of their die cast counterparts. As the total strain amplitude increased, the stress amplitude and plastic strain amplitude increased, while the pseudoelastic modulus decreased. The change in the modulus was attributed to the nonlinear (pseudoelastic) behavior caused by twinning-detwinning during cyclic deformation. The fatigue life increased with decreasing strain ratio, and partial mean stress relaxation occurred mainly in the initial 10-20% of the fatigue life. The fatigue life of theAM60B alloy improved after solution or solution-aging treatment, and the monotonic strength increased by aging, while the thixomolded condition itself exhibited moderate monotonic strength and fatigue life.

scholarly journals The Effect of LFC Process Variables on Solidification and Thermal Response of AZ91E Magnesium Alloy Castings

2021 ◽  
Author(s):  
Lukas Bichler
Keyword(s):  
Thermal Analysis ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Metal Flow ◽  
Mold Filling ◽  
Second Phase ◽  
Process Variables ◽  
Pyrolysis Products ◽  
Alloy Castings ◽  
Non Equilibrium

Magnesium alloys are gaining in popularity as materials of choice for automotive and aerospace applications. Magnesium alloys have the lowest density of all structural metals, effectively making their specific properties highly attractive. Lost Foam Casting (LFC) is a novel near-net-shape manufacturing process utilizing expanded polystyrene (EPS) as a mold filler. Presence of the EPS in the casting cavity promotes formation of unique casting defects.These include misruns, folds, entrapped polystyrene pyrolysis products and potentially increased levels of gas porosity. There is very little published literature on the feasibility of casting magnesium alloys by the LFC process. This research was an attempt to evaluate the effect of selected LFC process variables on AZ91R magnesium alloy castings produced by the LFC process. In this work, the effect of melt superheat, casting section thickness, EPS foam properties and the application of vacuum during mold filling were investigated and correlated to the casting quality and molten flow behavior. Further, detailed thermal analysis was carried out to determine the solidification history of the castings. The results of the thermal analysis were used to determine the effect of the cooling rate on the development of the casting microstructure. Moreover, the morphology and the mode of second phase (Mg17Al12) precipitation were studied and quantified. The results suggest that application of vacuum during the mold filling process increased the metal flow lengths. However, the casting soundness deteriorated due to the applied vacuum. Variations in the density of the vacuum cast horizontal bars were explained through the presence of partially solidified metal. The molten metal flow was further influenced by the foam density and bead fusion. Greater flow lengths were observed in the high density 1.6 pcf foam castings. in the low density 1.3 pcf foam castings, numerous casting defects were associated with the presence of the liquid-EPS pyrolysis products. In general, the thermal analysis suggested that non-equilibrium alloy solidification promoted the formation of the lamellar non-equilibrium Mg17Al12 precipitate, and this was confirmed by optical microscopy.

Continuous Casting of Magnesium Billets for Semi-Solid Processing

2005 ◽  
Vol 475-479 ◽  
pp. 517-520
Author(s):  
Hwa Chul Jung ◽  
Kwang Seon Shin
Keyword(s):  
Aluminum Alloys ◽  
Continuous Casting ◽  
Magnesium Alloys ◽  
Casting Process ◽  
Az91 Alloy ◽  
Attractive Alternative ◽  
Limited Information ◽  
Continuous Casting Process ◽  
Dendritic Microstructure ◽  
Semi Solid

Semi-solid processing is recognized as an attractive alternative method for the near net-shape production of engineering components. Although there has been a significant progress in semi-solid processing of aluminum alloys, very limited information is available on semi-solid processing of magnesium alloys, except for the thixomolding process. Continuous casting process has been utilized to produce the billets with the desirable cross-section at a reduced production cost for many metals, such as steel, copper and aluminum alloys. It has also been commercially utilized to produce the aluminum billets with non-dendritic microstructure for subsequent thixocasting process. However, continuous casting of magnesium billets for semi-solid processing has not yet been commercialized due to the difficulties involved in casting of magnesium alloys. In the present study, a continuous casting process has been developed for the production of the cylindrical billets of magnesium alloys for the subsequent thixocasting process. In order to obtain the desired non-dendritic microstructure with an excellent degree of homogeneity both in microstructure and composition, an electromagnetic stirring system has been utilized. A continuous casting process has been proven to be an efficient way to produce the high quality billets of magnesium alloys for semi-solid processing. A prototype air conditioner cover was produced using the continuously cast billets of AZ91 alloy.

Application of Semi-Solid Forming to Magnesium Alloys with High Al and Zn Contents

2003 ◽  
Vol 419-422 ◽  
pp. 629-634 ◽  
Author(s):  
Nyoman Antara ◽  
Katsumi Suzuki ◽  
Toru Kayuta ◽  
Shigeharu Kamado ◽  
Yo Kojima
Keyword(s):  
Magnesium Alloys ◽  
Semi Solid
Sign in / Sign up

Export Citation Format

Share Document