Research on Metamorphic Vibration Casting Process Based on EDEM-FLUENT Coupling

In order to reduce the defects of investment casting and improve its casting quality, vibration technology and casting technology are combined effectively and the effect of vibration degree of freedom, frequency and amplitude on the filling ability of liquid metal are studied by means of EDEM-FLUENT solid liquid coupling visualization. With the use of orthogonal test method, the sensitivity of the particles towards each parameter index is obtained. Optimal vibration parameters are chosen and then the best variable cell vibration casting solution is obtained.

New Semisolid Casting of an Al-25Wt.% Mg2Si Composite Using Vibrating Cooling Slope

Al-Mg2Si composites have gained considerable attention because of their attractive properties such as low density, improved wear resistance and good castability. However, when in-situ routes are used for processing of these composites, the formation of coarse Mg2Si particles with sharp cornersis inevitable and is detrimental for the composite properties. This problem is intensified when a hypereutectic composition such as Al-25wt.% Mg2Si alloy is processed. In the present study, an innovative semisolid technique termed as the Vibrating Cooling Slope (VCS) has been applied to produce a sample of in-situ Al-25wt.% Mg2Si composite.This technique combines the conventional cooling slope and vibration casting methods into an integrated one for producing fine and globular structures in the as-cast condition. An inclined plate was prepared from a 10mm thickness copper plate and was coated by boron nitride. This platecould vibrate mechanically in the vertical direction at a predetermined frequency by the aid of four springs and an electric motor. The molten Al-16.5wt.%Mg-9.4%Sialloy with 100oC superheat was poured on the surface of this cooling slope (set at 45° inclined angle)while it was vibrating at the frequency of 40 Hzandamplitude of 400 μm.The semisolid alloy travelled the length of 40 cm on the slope before being poured into a steel mold (60 mm internal diameter and 35 mm in height). Also for the purpose of comparison, gravity casting (GC) and conventionally still cooling slope casting (CS)were carried outboth using the same mold and with the same superheat.The samples were sectioned, polished and subjected to metallographicstudies,porosity and hardness measurements. It was concluded that CS and VCS techniques resulted in a decrease in the size of Mg2Si particles by about 50%and 70% respectively when compared with the gravity casting. However, the increased shape factor of Mg2Si particles in the VCS and CS processed samples was insignificant as compared with GC. Although in comparison with GC, the VCS processed sample showed a higher porosity level, it exhibited a higher hardness value. These results were attributed to the finer and modified microstructure obtained via this newly developed technique.

Design of Three-Dimensional Parallel Vibration Casting Machine

In order to reduce casting defects and improve casting quality, the author has developed a three-dimensional parallel vibration casting machine based on parallel mechanism. The paper introduces the three-dimensional parallel vibration casting machine in structure composition and functional properties, the casting machine degree of freedom of excitation mechanism is calculated, its motion performance is analyzed, and the kinematics equations are established. The designed casting machine achieves support and excitation functional separation of moving parts which takes complete decoupling of hybrid mechanism 2PRRR-P (2R ) as excitation mechanism, realizing flask vibration along the X, Y, Z three directions. Test results show that, the casting machine can significantly improve casting quality, raise labor productivity, save casting raw materials, and reduce the production costs.

Effect of Electromagnetic Vibration on Microstructures of Semi-Continuous Casting AZ80 Magnesium Alloy Billet

Microstructures and macrosegregation of AZ80 magnesium alloy billets cast with and without the electromagnetic vibration were investigated. Compared with the conventional DC casting, microstructures of the billet have been greatly refined and the macrosegregation had been effectively reduced in electromagnetic vibration casting conditions. Increasing the electromagnetic vibration intensity, including both the stationary magnetic field and alternating magnetic field, leads to finer grains and more uniform distribution of solute elements in the billet.

Process of Equiaxed Grains of RE-Al Alloy under Slope Vibration

A new technique using slope vibration casting process during heating and isothermal holding period to prepare Al-7Si-2RE alloy has been studied. The small, near-spherical and non-dendritic microstructure with the semi-solid processing requirements has been obtained. Experiments show that the cooling method, pouring process and the convection of melt caused by slope vibration had significant effects on the formation of near-spherical primary gains. The water-cooled copper mold casting with slope vibration at the temperature near liquidus can obtain Al-7Si-2RE alloy with small homogeneous equiaxed grains, the average grain diameter is 48.3μm, and the average grain roundness is 1.92.