This paper presents an analysis of an advanced squeeze casting process suitable for the manufacturing of high performance industrial components more quickly and cheaply. After short description of the process some produced components are considered. The components, in A356 and A380 alloys, have been T6 heat treated and their soundness has been certified by non destructive tests. Standard samples for impact test, as well as for fracture rupture strength have been machined directly from the previous components. After the execution of the tests the fracture surface of samples has been observed by SEM in order to analyze details and to evaluate the influence of the process and of the alloy on the fracture behaviour. On polished transverse sections of samples the microstructure of the alloy has been observed, highlighting the presence of very small and uniformly distributed intermetallic particles in a mainly globular shaped microstructure as expression of the attained semi-solid conditions during the process.
In this paper a self-hardening Al-based alloy (AlZn10Si8Mg) is proposed for automotive applications as an alternative to the A357 (AlSi7Mg0.6) T6 heat treated alloy. The properties of the AlZn10Si8Mg alloy have been monitored and compared to those of the A357 alloy which is already employed in the targeted automotive industry. The samples have been submitted to microstructural analysis and mechanical characterization, while the presence of defects on the fractured surface has been identified by fracture surface analysis. A relationship between defects and mechanical performances has been identified. The corrosion resistance of the alloys has also been investigated according to the Standard BS 11846. On the basis of the results obtained till now, the AlZn10Si8Mg alloy is a good candidate for the proposed automotive application.
An emerging and still poorly explored application of aluminum foams is their potential use as permanent cores (inserts) in the casting of aluminum alloys. In this context, Al-based foams can introduce a weight reduction, the obtainment of cavities, a strength increase, the ability to absorb impact energy and vibration, acoustic insulation ability, the possibility to simplify the technological processes (no removal/recycling of traditional sand cores), and finally, they can be fully recyclable. Cymat-type Al foams with thin outer skin were used as permanent cores in Al-alloy gravity casting in the present research. Al-foams were characterized in terms of porosity, density, cell wall and skin thickness, surface chemical composition and morphology, and compression resistance. Cast objects with foam inserts were characterized by means of optical microscopy. The preservation of up to 50% of the initial porosity was observed for foam inserts with higher density. Metallurgical bonding between the foam core and the cast metal was observed in some regions.
Self-hardening aluminum alloys (AlZn10Si8Mg, EN-AC-71100) represent an interesting innovative class of material for the production of automotive and aerospace components with high-mechanical strength and good corrosion resistance. The aim of the present is related to the investigation of the intergranular corrosion resistance of an innovative class of self hardening alloys. Microstructural characterization combined with compositional analysis has been carried out by Optical and Scanning Electron Microscope equipped with Energy X-rays Dispersive Spectroscopy unit. Three-point bending test and Charpy Impact test have been performed and the corrosion resistance of the alloys has been investigated according to standard BS 11846, method B. The susceptibility of the alloy to intergranular corrosion has been assessed evaluating the maximum corrosion depth and the weight loss of the alloy after corrosion test. The results obtained have been demonstrated that the corrosion resistance of the alloy can be achieved by Mg addition.
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