Confidential NETANYA PLASMATEC LTD Innovative Plasma Stirring (PTC) Process semi-continuous casting...

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NETANYA PLASMATEC LTD

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

Normal casting after homogenization

PTC as cast

The end of homogenization treatment for The end of homogenization treatment for 6XXX Aluminum billets6XXX Aluminum billets

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Plasma stirring process for Aluminum Plasma stirring process for Aluminum 6XXX billets6XXX 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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Creates enormous shear forces by very effective stirring

Plasma stirringPlasma stirring

Induces electric and magnetic fields in the molten metal

Creates changing current density flow in the molten metal

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 Plasma stirring process benefits for Aluminum 6XXX billetsAluminum 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 Plasma eliminates the homogenization processprocess

Normal casting Plasma stirring as cast

HomogenizationExtrusion

5850C for 14 hours

T5 Aging

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PTC as cast billets

PTC profiles without homogenization

Extrusion of as cast billets

End products for clients

Plasma eliminates the homogenization processPlasma eliminates the homogenization process

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Plasma as cast billet directly to extrusion 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.

1. Casting aluminum 6XXXof 180mm diameter billets

2. DC casting of billets without plasma arc (at the same batch)

3. Casting temperature 700-710oC4. Casting speed

100-120mm/minute5. 10-14 hours homogenization

treatment was done in 575-585oC

6. Extrusion was done after homogenization treatment.

Normal casting

1. Casting aluminum 6XXX of 180mm diameter billets

2. DC casting of billets with plasma arc (at the same batch)

3. Casting temperature 700-710oC4. Casting speed 100

-120mm/minute5. No homogenization treatment

was done 6. Extrusion was done without

homogenization treatment.

Plasma stirring casting

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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/minute4. Alumina ring was applied to allow argon surrounding around

the electrode

Plasma stirring parametersPlasma stirring parameters

Electrode and ring Gripper and electrode

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Extruded ProfilesExtruded Profiles

Normal With Homogenization PTC Without Homogenization

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

homogenized plasma as cast billet

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Normal With Homogenization PTC Without Homogenization

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Extruded ProfilesExtruded 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 resultsExtrusion 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 highLevels of Copper (Cu) (0.06-0.12%) and Iron (Fe)(0.3-0.45%) which significantly decrease the formability.

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SurfaceMid RadiusCenter

Samples for Optical MicroscopySamples for Optical Microscopy

• The samples were mounted in Bakelite• Polished by SiC papers and alumina suspension etched in Keller’s

reagent.

1 rectangular samples were taken (2 cm thickness), from Mid radius

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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


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PTC 175A as castNormal casting after homogenization

• Reducing macro segregation by distributing the alloying elements in the billet during the solidification process


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ConclusionsConclusions

The Plasma stirring:

1. Eliminates the necessity for homogenization treatment

2. The PTC as cast billets without homogenization revealed the same extrusion behavior as normal casting with homogenization

3. Reduces macro segregation by distribution of the alloying elements in the billet during the solidification process

4. Reduces the micro segregation by defusing the alloying elements from the boundaries into the grains during the solidification process

5. Increases yield by improving billets surface quality

6. The anodize quality is in the same level

7. Improves mechanical properties of the extruded product

8. Reduces and refines DAS

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PTC moviePTC movie

Confidential NETANYA PLASMATEC LTD Innovative Plasma Stirring (PTC) Process semi-continuous casting...

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