PetroMat

The correlation between the evaluation of the mechanical and of the fatigue behaviour of the rheocast, T5 and T6 heat treated SSM A356 aluminium alloy with respect to the microstructures of the component has been investigated. The study has been carried out on a suspension arm injected in a rheocasting 800 tons plant in Stampal S.p.A. The new rheocasting is a process that allows obtaining the alloys in a semisolid state directly from the liquid state, by controlled cooling of the molten alloys.

The paper deals with the surface hardening of stainless steels trough the application of suitable plasma nitriding cycle to different austenitic and martensitic grades. The cylindrical shaped samples, 18 to 30 mm in diameter and 50 mm long, have been plasma nitrided in an industrial plant, performing the heating in hydrogen based plasma up to 420 °C for 2 h, then the temperature has been elevated at 530 °C in plasma obtained by H2 - N2 (80% and 20% respectively), the cooling has been done in nitrogen based atmosphere.

Al-based alloy, produced by a patented, namely Liquid forging, process is studied for automotive application. The patented procedure leads to produce high resistance and high toughness components with the possibility to realise T6 heat treatment. The influence of some process parameter (filling rate and time) on the alloy properties is investigated. The benefits of T6 heat treatment on the performance of Al-based components is considered. The alloy morphological and mechanical characterization has been realised in different conditions and a comparison of these data has been carried out.

Analysis of the grain growth on the galvanic deposition of aluminium is presented aiming to find an optimized process and corresponding ad-hoc designed experimental set-up which guarantees an enhanced quality of the coated layer. In particular, the effects of some process parameters, i.e. deposition time, current density and the liquid agitation on the coating properties of aluminium have been experimentally investigated.The properties of the deposited layer has been evaluated.

One of the most favored welding techniques of high strength aluminium alloy is commonly metal arc welding (MAW) process due to its high productivity and relatively low production cost. Apart from other process parameters (e.g. joint design) the filler material has a significant influence on the microstructure of the weld at the joint and consequently on the endurance limit of the end-product. The above considered process was used to weld AA6082 aluminum alloy using two different filler metals, Al4043 and Al5356 respectively.

In this paper dimensional stability investigation in two hypoeutectic composition is proposed. Specifically, the study of some samples in AlSi7Mg0,3 and AlSi8,5Cu3,5 alloys is realized and a comparison of the obtained data will be discussed. Starting from dilatometric analysis the dimensional modification of the alloys is monitored. For both materials analysis has been conducted by heating to 500°C at various heating rates and determining the activation energy for the decomposition process of the supersaturated solid solution.

Components in the field of automotive application produced by a modified squeeze casting process have been considered. This innovative process has been oriented toward the manufacturing of high resistance and high toughness automotive parts using A380 alloys and they have been subjected to T6 heat treatment. Standard samples have been machined directly from real automotive components for tensile properties evaluation and hardness values determination. Superior mechanical characteristics have been obtained thanks to the low porosity content and to the particular microstructure features.