Extrudability improvement and energy consumption estimation in Al extrusion process of a 7003 alloy

In a view point of mechanical property of medium strength alloy such as A7003 aluminum alloy, it is necessary to increase Mg content in the alloy however an increment in Mg content has an adverse effect on the extrudability. Furthermore, it has been generally practiced to reduce the Mg content for enhanced recovery efficiency during Al scrap recycling in the aluminum industry. Therefore, it is important to select the amounts of alloy elements for mechanical property and extrudability in medium strength A7003 alloy. To examine the effect of Mg content on extrudability in A7003, hot extrusion experiments and then microstructure examination by XRD, SEM and EPMA have been performed. The quantitative analysis of energy consumption and CO2 emission for production of A7003 extruded bar are estimated with different process variables such as Mg content, extrusion process (direct or indirect extrusion) and billet pre-heating process (heating by light oil or LPG). The estimation of energy consumption is performed in a stage except mining and extraction (from shipping to gate) to investigate an influence of the parameters on energy consumption and CO2 emission in detail. As Mg content is increased, the flow stress and the extrusion pressure for A7003 alloy are increased. It has been thought that an increment in extrusion pressure with increasing Mg content is caused by the solid solution hardening of Mg atoms in the matrix and an increment in volume fraction of intermetallic compound, Mg2Si. The energy consumptions can be reduced when lower content of Mg in A7003 alloy and indirect extrusion process are used. It has been found that CO2 emission in billet heating process can be reduced when induction heating process is introduced.