Aluminum Melt Degassing Process Evaluation Depending on the Design and the Degree of the FDU Unit Graphite Rotor Wear

Abstract

One of the most important indicators of casting quality is porosity. The formation of pores is largely conditioned by the presence of hydrogen in the batch and subsequently in the melt. The gasification of the melt is the primary factor increasing the porosity of casts. This paper addresses the issue of reducing the melt gasification by using FDU (Foundry Degassing Unit) unit. The gas content in the melt is evaluated by determining the Dichte Index depending on the geometry and the degree of the FDU unit rotor wear. For experiments performed under the operating conditions, three types of graphite rotors with different geometries are used. The extent of melt gasification and the Dichte Index are monitored during the rotor wear, at a rate of 0%, 25%, 50%, 75% and 100% rotor wear. Secondly, the chemical composition of the melt is monitored depending on the design and wear of the rotor. It is proven that the design and the degree of rotor wear do not have significant effect on the chemical composition of the melt and all evaluated samples fell within the prescribed quality in accordance with EN 1706. With regard to the overall comparison of the geometry and wear of individual rotor types, it has been proven that, in terms of efficiency, the individual rotors are mutually equivalent and meet the requirements for melt degassing throughout the service life.

Assessment of refining efficiency during the refining cycle in a foundry degassing unit in industrial conditions

“…An example of this is the testing of different types of rotor materials 36 . During refining, the rotors are in direct contact with the molten material, which significantly affects their service life 37 . In order to obtain appropriate results, it is therefore necessary to conduct experiments directly in the operating conditions of the foundry 38 .…”

Effect of Degassing Parameters on Mechanical Properties of EN AC-46000 Gravity Die Castings

“…The fracture surfaces of the post-mortem tensile bars showed both blowholes and oxide layers, responsible for lowering the strength properties of the tested alloy. In addition to the above-mentioned tests, aluminum casting alloys were the subject of many other tests in terms of their degassing and hydrogen content [ 30 , 31 , 32 , 33 ].…”