Abstract
The industrial production of products, such as foil and aluminium alloy strips, begins with the production of semi-finished products in the form of slabs. These are produced by the continuous casting process, which is quick and does not allow the equilibrium conditions of solidification. Non-homogeneity—such as micro and macro segregation, non-equilibrium phases and microstructural constituents, as well as stresses arising during non-equilibrium solidification—are eliminated by means of homogenization annealing. In this way, a number of technological difficulties in the further processing of semi-finished products can be avoided. The aim of this research was the optimization of the homogenization annealing of the EN AW 8006 alloy. With the Thermo-Calc software, a thermodynamic simulation of equilibrium and non-equilibrium solidification was performed. Differential scanning calorimetry (DSC) was performed on selected samples in as-cast state and after various regimes of homogenization annealing and was used for the simulation of homogenization annealing. Using an optical microscope (OM), a scanning electron microscope (SEM) and an energy dispersion spectrometer (EDS), the microstructure of the samples was examined. Based on the results, it was concluded that homogenization annealing has already taken place after 8 h at 580 °C to the extent, that the material is then suitable for further processing.
Highlights
Due to their relatively high strength, combined with their sufficient ductility, the non-hardenable alloys Al-Fe-Mn-Si are largely used in the automotive industry, cooling systems, civil engineering, etc.Al-foil can be produced either by starting from a conventional direct chill (DC) cast ingot which is hot rolled to a strip of about 2–5 mm, or from continuous casting a 6–7-mm-thick sheet and cold rolling it to an intermediate gauge of about 0.4–1 mm
Spherical particles of aluminium can bemicroscopy seen on the surface foil alloyinduring homogenization was investigated using optical boride and electron as well of as the sheets. They are small in size and non-deformable particles compared to the ductile aluminium differential scanning calorimetry (DSC)
The results indicate that the temperature range for the dissolution is 550–620 ◦ C
Summary
Due to their relatively high strength, combined with their sufficient ductility, the non-hardenable alloys Al-Fe-Mn-Si are largely used in the automotive industry, cooling systems, civil engineering, etc. Al-alloys will always comprise large Fe-bearing phases because of the very low solubility of Fe in Al. The type, volume, size, and especially the morphology of these constituent particles have an impact on ductility and formability. Pre-heating or homogenization annealing prior to hot rolling will affect both processing and final foil properties by leading to the formation of fine secondary intermetallic phases or so-called ‘dispersoids’ [6,7]. At medium Si contents and/or high temperatures, the α-AlFeSi phase is obtained, whereas the chemical composition of this phase shows rather large scatter and is described as Al8 Fe2 Si or Al12 Fe3 Si. The ratio of Fe:Si may vary between 2:1 and 3:1 in at. If Mn is present, the α-AlFeSi phase is replaced by an isostructural quaternary α-Al(Mn,Fe)Si phase from the system presented in Figure 1c, which may show large variation in exact chemical composition [6,16]
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