Metal casting Billets elimination for all 6XXX billets of SEMI CONTINUOUS

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The end of homogenization treatment for 6XXX
Aluminum billets
Innovative Plasma Stirring (PTC) Process
semi-continuous casting for Aluminum billets
eliminates the necessity for homogenization
before plastic deformation processes
The PTC stirring during solidification dissolves
the inter dendritic phase into the grains and
reduces the macro segregation in the cross
section
PTC as cast
Normal casting after homogenization
2
Plasma stirring process for Aluminum 6XXX billets

• The plasma stirring process is an add-on
  technology for existing casting line
• The plasma stirs the liquid aluminum during the
  solidification, by applying rotating plasma arc
• The rotating plasma arc induces very powerful
  magnetic and electric fields into the molten
  metal
• This stirring effect eliminates the necessity for
  homogenization treatment, increases yield,
  improves mechanical properties and homogeneity
  and reduces DAS size

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Plasma stirring
Creates changing current density flow in the
molten metal
Induces electric and magnetic fields in the
molten metal
Creates enormous shear forces by very effective
stirring  
Breaks the growing dendrites and creates a new
nucleation center on each fracture
Creates smaller uniform dendrites and reduces
significantly porosity and segregation levels
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Plasma stirring process benefits for Aluminum
6XXX billets

• The plasma stirring process benefits for aluminum
  6XXX in comparison to homogenized (6-14 hours)
  normal DC billet
• Reducing macro segregation by distribution of
  the alloying elements in the billet during the
  solidification process
• Reducing the micro segregation by defusing the
  alloying elements from the boundaries into the
  grains during the solidification process
• Saving completely the homogenization treatment
  required for thermo mechanical process, such as
  extrusion, forging, rolling etc.
• Improving significantly the surface quality of
  the billet and increases extrusion yield
• Improving mechanical properties, such as
  elongation (e)

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Plasma eliminates the homogenization process
Normal casting
Plasma stirring as cast
Homogenization
Extrusion
T5 Aging
5850C for 14 hours
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Plasma eliminates the homogenization process
PTC as cast billets
Extrusion of as cast billets
End products for clients
PTC profiles without homogenization
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Plasma as cast billet directly to extrusion
The plasma stirring was tested on more than 100
direct chilled casting (DC casting) billets on
commercial lines of Aluminum 6XXX at several
casting houses.
Plasma stirring casting
Normal casting

• Casting aluminum 6XXX of 180mm diameter billets
• DC casting of billets with plasma arc (at the
  same batch)
• Casting temperature 700-710oC
• Casting speed 100 -120mm/minute
• No homogenization treatment was done
• Extrusion was done without homogenization
  treatment.

• Casting aluminum 6XXXof 180mm diameter billets
• DC casting of billets without plasma arc (at the
  same batch)
• Casting temperature 700-710oC
• Casting speed 100-120mm/minute
• 10-14 hours homogenization treatment was done in
  575-585oC
• Extrusion was done after homogenization
  treatment.

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Plasma stirring parameters

1. 40mm graphite electrodes were placed on top of
   the billets.
2. Several plasma stirring energies were applied
   9kWh/ton - 15kWh/ton
3. Argon flow was 6 litter/minute
4. Alumina ring was applied to allow argon
   surrounding around the electrode

Electrode and ring
Gripper and electrode
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Extruded Profiles

• Complicated types of profiles were chosen
• Extrusion was done for homogenized normal cast
  billet and for not homogenized plasma as cast
  billet

Normal With Homogenization
PTC Without Homogenization
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Normal With Homogenization
PTC Without Homogenization
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Extruded Profiles
Complicated types of profiles were chosen The
PTC as cast billets without homogenization
revealed the same extrusion behavior as normal
casting with homogenization
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Extrusion results

• The PTC as cast billets without homogenization
  revealed the same extrusion behavior as normal
  casting with homogenization.
• The mechanical properties are in the same level.
  Elongation is increased
• The anodize quality is in the same level

The billets were cast from secondary Aluminum
thus contained very high Levels of Copper (Cu)
(0.06-0.12) and Iron (Fe)(0.3-0.45) which
significantly decrease the formability.
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Samples for Optical Microscopy
1 rectangular samples were taken (2 cm
thickness), from Mid radius

• The samples were mounted in Bakelite
• Polished by SiC papers and alumina suspension
  etched in Kellers reagent.

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Normal casting after homogenization
PTC 125A as cast

• Reducing macro segregation by distributing the
  alloying elements in the billet during the
  solidification process
• Reducing the micro segregation by defusing the
  alloying elements from the boundaries into the
  grains during the solidification process

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Normal casting after homogenization
PTC 175A as cast

• Reducing macro segregation by distributing the
  alloying elements in the billet during the
  solidification process
• Reducing the micro segregation by defusing the
  alloying elements from the boundaries into the
  grains during the solidification process

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Conclusions

• The Plasma stirring
• Eliminates the necessity for homogenization
  treatment
• The PTC as cast billets without homogenization
  revealed the same extrusion behavior as normal
  casting with homogenization
• Reduces macro segregation by distribution of the
  alloying elements in the billet during the
  solidification process
• Reduces the micro segregation by defusing the
  alloying elements from the boundaries into the
  grains during the solidification process
• Increases yield by improving billets surface
  quality
• The anodize quality is in the same level
• Improves mechanical properties of the extruded
  product
• Reduces and refines DAS

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PTC movie