The PTC stirring during solidification dissolves the inter dendritic phase into the grains and reduces the macro segrega

1. 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

3. 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

4. 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%)

5. Plasma eliminates the homogenization process • Normal casting Plasma stirring as cast • Homogenization • Extrusion • T5 Aging • 5850C for 14 hours

6. Plasma eliminates the homogenization process Extrusion of as cast billets PTC as cast billets End products for clients PTC profiles without homogenization

7. 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.

8. Plasma stirring parameters • 40mm graphite electrodes were placed on top of the billets. • Several plasma stirring energies were applied – 9kWh/ton - 15kWh/ton • Argon flow was 6 litter/minute • Alumina ring was applied to allow argon surrounding around the electrode Electrode and ring Gripper and electrode

9. 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 PTCWithout Homogenization

10. Normal With Homogenization PTCWithout Homogenization

11. 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

12. 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.

13. Center Surface Mid Radius 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 Keller’s reagent.

14. 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

15. 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

16. 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

17. PTC movie