Abstract: By the severe plastic deformation, the equal channel angular pressing method (ECAP) has
been used for producing metal materials with the ultra-fine grain size and specific mechanical
properties, in particular high yield strength. Analytical approaches have also been studied by few
researchers. However, none of the previous analyses have taken into account the strain hardening of
the material by considering the microstructure evolution. In this paper, the deformation behavior and
the strain harden of aluminum during equal channel angular pressing was calculated on the basis of a
dislocation evolution model. Then simulated stress, strain and strain distribution and strain hardening
were analyzed. The strain is seen to rapidly increase when the material passes the shear area. This
makes a maximum value of stress. And for the congregation of dislocation density, the maximal value
of strain increase with the process continuing.
Abstract: The horizontal direct chill (HDC) casting process is a well-established production route for
an aluminum alloy ingot; however, the ingot may suffer from inhomogeneous microstructures and
serious macrosegregation due to the unbalanced cooling condition and gravitational effect. In order to
control the defect, a low frequency electromagnetic field has been applied in the HDC casting process
and its influences on microstructures and macrosegregation have been studied. The results show that
the low frequency electromagnetic field can improve macrostructures, reduce inhomogeneous
microstructures and macrosegregation in HDC product; and two main parameters of the
electromagnetic field—density and frequency influence the microstructures and solution distribution
along the diameter of the ingot significantly. In the range of ampere-turns and frequency employed in
the experiments, the optimum ampere-turns and frequency have been found to be 10000At, 30Hz.
Abstract: On the basis of analyzing the relationship between filling mould ability and surface tension
of Al-Si alloy, a new method was put forward that filling mould ability can be fast evaluated by
surface tension. To fast test surface tension of Al-Si alloy in front of furnace, a new apparatus had
been developed and a new mould had been designed to appraise the ability of filling acute angle of
Al-Si alloy by authors. By means of the self-developed new apparatus and new mould, the
relationship between surface tension and filling mould ability had also been proved and gotten by
many experiments on Al-Si alloys. Depending on the relationship the filling mould ability of Al-Si
alloy can be evaluated by surface tension in few seconds before cast.
Abstract: Aluminum alloy sheet is becoming one of the main materials to take the place of steel
components to reduce the vehicle mass due to the advantage of low special density, high strength and
corrosion resistance. To predict the formability during the aluminium alloy sheet forming
accurately, , a ductile fracture criterion developed by the authors, was for numerical simulation, in
this paper. Fracture behavior in square-cup forming of the aluminium alloy LF21M was predicted by
means of the criterion. Comparison of the predicted results with experimental values shows that the
critical punch stroke and the fracture initiation position in square-cup forming of the aluminium alloy
have been predicted successfully by the criterion.
Abstract: Low frequency electromagnetic casting is a new developed technology that appears in the
recent years. In this paper, a comprehensive mathematical model has been developed to describe the
interaction of the multiple physics fields during LFEC (low frequency electromagnetic casting)
process. The model is based on a combination of the commercial finite element package ANSYS and
the commercial finite volume package FLUENT, with the former for calculation of the
electromagnetic field and the latter for calculation of the magnetic driven fluid flow, heat transfer and
solidification. Moreover, the model has been verified against the temperature measurements obtained
from one 7XXX aluminum alloy billet of 200mm in diameter, during the LFEC casting processes,
respectively. There was a good agreement between the calculated results and the measured results.
Further, the effects of electromagnetic frequency on fluid flow, temperature field and solidification
during LFEC process have investigated numerically by using the mathematic model. The choosing
criterion of the electromagnetic frequency during LFEC process has been used in order to obtain the
best structure of the billets by analyzing the effects of fluid flow and temperature field on the
solidification process in the presence of electromagnetic field.
Abstract: The key to enhance the precision of sheet metal stamping parts is accurate prediction and
control of the springback. And one of the dominant factors of springback is the elastic modulus. The
change of elastic modulus with plastic deformation was experimentally studied for the annealed LY12
and the annealed LF21 aluminum alloy respectively, and the changing role of elastic modulus with
plastic deformation was obtained. By inverse pole figure from the X-ray diffraction analysis, the
effects of the material original textures and their changing with plastic deformation on the elastic
modulus were studied. And by positron annihilation lifetime spectrum , the influence of lattice
distortion caused by crystal defect during plastic deformation on the elastic modulus was investigated.
The micromechanism of the elastic modulus changing with plastic deformation for aluminum alloy is
revealed, which lays a foundation for improving the stamping parts’ precision.
Abstract: A systematic homogenization treatment on Al-Li-Cu-Mg-Mn-Zr alloy, within the
temperature range from 500C to 540C for 24h or 36h was conducted. Microstructure and alloying
elements distribution before and after homogenization treatment were studied by optical microscope,
SEM, EDS and XRD. The results showed that in the as-cast condition Cu segregated at grain
boundary and formed θ(Al2Cu) phase. With the homogenization temperature increased and time
prolonged, the amount of the remained particles at grain boundaries decreased, and the alloying
elements distribution became more homogeneous. It has been found that the homogenization
temperature has more obvious effects on the microstructure and mechanical properties than time.
However, the alloy homogenized at temperatures above 540C was overheated. Furnace cooling
generates large amounts of precipitates in the matrix. The best homogenization parameter of the
Al-Li-Cu-Mg-Mn-Zr alloy was determined as 530C for 24 h followed by air cooling.
Abstract: The effect of pulse electric current with different density on solidification structures of
hypoeutectic Al-7%Si, Al-10%Si and hypereutectic Al-22%Si alloys was studied. The shape and
distribution of α-Al and Si were analysed.The experimental results showed that α- Al of Al-7% Si
alloy is shortened when applied a pulse electric current during the solidification, and the
microstructure turns from the obvious columnar crystal into rosette. After treatment with pulse
electric current, the primary Si of Al-22%Si alloy was refined obviously. When the discharge voltage
was 3kV, Si tended to gather at the edge of the sample and the primary α- Al appeared in this
hypereutectic alloy. When the discharge voltage was 6kV, the primary Si was refined much more and
distributes uniformly. Pulse electric current treatment had no evident effect on the approximate
eutectic Al-10%Si alloy. The magnetic force was analysed under pulse electric current, and the reason
of the phenomenon was discussed
Abstract: According to the characteristics of transient solidification and continuous rheology in roll
casting process, and by modifying clamp system and loading way of molten metal, physical
simulation of continuous roll casting process was realized in conjunction with Gleeble-1500
thermal-mechanical simulation testing machine in the present study. And relative rheologica1
constitutive models fitting the process were set up. A method to conduct multi-nonlinear
thermo-mechanical coupling analysis suitable for aluminum strip roll casting process was explored by
the secondary development of ANSYS finite element analysis software. The variation rules of
temperature and deformation field were obtained. It has been found that the simulating models are
compared with experimental results.
Abstract: In the investigation, the continuous extrusion forming (CONFORM) process of aluminum
alloy rectangular hollow conductor has been studied by three-dimensional finite-element method
based on Software DEFORM-3D. The rigid-viscoplastic constitutive equation was employed in the
model. Distributions of velocity field, strain field, stress field and temperature field were obtained in
the forming process. The results will give effective guidelines to optimize the processing parameters
and to select, the die structure and die materials.