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Aluminium alloys casting Problems (2 of 2 )

Edit: Smart Mold Technology Limited    Date: Sep 30, 2015

 

Melting and metal treatment:


Aluminium alloys may be melted in various ways. Coreless and channel induction furnaces, crucible and open-hearth reverberatory furnaces fired by natural gas or fuel oil and electric resistance and electric radiation furnaces are all in routine use. The nature of furnace charge is as different and important as the choice of metal casting operations. The furnace charge may differ from pre-alloyed ingot of high quality to charge made up of low quality scrap. Even under best melting and melt holding situation melted aluminium is at risk to these types of degradation.


a) With time at temperature, adsorption of hydrogen results in increased hydrogen content.


b) With time at temperature, oxidation of melt occurs.


c) Transient elements featured by low vapor pressure and high reactivity are reduced.

Turbulence or agitation of melt and increased holding temperature, significantly increase the rate of hydrogen solution oxidation and transient element loss. The mechanical properties of aluminium alloys depend on casting soundness which is highly influenced by hydrogen porosity and entrapped non metallic inclusions. Aluminium alloys casting and products manufactured by them are things of the future due to their cost effectiveness and lightweight.

 

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