Shanghai Jiao Tong University School of Materials Science and Engineering Effect of Electromagnetic Separation of Inclusions on the Mechanical Properties of A356 Alloy Baode Sun, Da Shu

1. Introduction Harmful effects of presence of nonmetallic inclusions in molten aluminum: Harmful effects of presence of nonmetallic inclusions in molten aluminum:  Decrease in fluidity  Promotion for porosity formation  Reduction in strength and toughness  Poor machinability and surface quality  Stress concentration and early failure Common inclusion removal method: Common inclusion removal method:  Ceramic Foam Filter Electromagnetic separation: Electromagnetic separation:  clean  efficient  stable

Principle of electromagnetic separation of inclusions: Principle of electromagnetic separation of inclusions: make use of the difference in the electrical conductivity between molten metal and inclusions make use of the difference in the electrical conductivity between molten metal and inclusions Separation of inclusions by applying alternating magnetic field

2. Experimental Process Objective ： A set of laboratory-scale apparatus combining filtration with electromagnetic separation was set up to process A356 alloy melt. Mechanical properties were tested to study the influence of different processing conditions. Experimental Alloy ： fresh/scrap A356 alloy

2.1 Experimental apparatus Electromagnetic separation apparatus for continuous processing of aluminum alloy melt

2.2 Processing conditions Melting  holding  degassing by C 2 Cl 6  holding  no processing  filtration only  cast test bars  T6 heat treatment  filtration & EM separation Parameters for electromagnetic separation Parameters for electromagnetic separation ： 15.6 kHz, 0.12 T, 8~20 s, 10 mm x 10 mm

3. Experimental Results Tensile properties: Tensile properties: ultimate tensile strength, elongation percentage ultimate tensile strength, elongation percentage Fracture observation Fracture observation

- The tensile strength of scrap A356 alloy after electromagnetic filtration was increased by 8.27%, approaching that of fresh alloy. 3.1 Tensile properties 1&4 - No processing, 2&5 – filtration only, 3&6 – filtration and electromagnetic separation

3.2 Fracture observation scrap Fracture surfaces of scrap A356 tensile test samples after different cleaning processes (a) MPa, 2.40%, (b).244.0MPa, 3.93%, (c) MPa, 4.17% (a) (b) (c) No processingfiltration only filtration & EM separation

fresh alloy: no filtration Fracture surface of fresh A356 tensile test sample without filtration （ MPa ， 3.84% ） (a) (b) (c)

Fracture surfaces of fresh A356 tensile-tested sample after filtration （ MPa ， 3.69% ） (a) (b) (c) fresh alloy: filtration only

fresh alloy: filtration and EM separation Fracture surface of fresh A356 tensile test sample after filtration and EM separation treatment (a) (b)

4. Conclusions EM separation process combined with filtration can effectively remove most of the micro-sized inclusions in A356 alloy casting; EM separation process combined with filtration can effectively remove most of the micro-sized inclusions in A356 alloy casting; After processing with EM separation, the tensile strength of A356 alloy scrap was increased by 8.27%, approaching that of fresh alloy. After processing with EM separation, the tensile strength of A356 alloy scrap was increased by 8.27%, approaching that of fresh alloy.

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