ALT

Formulation and characterization of new aluminium alloys produced by ingot metallurgy for high temperature applications (250ºC)

 Partecipanti

Mappa

 Word cloud

Esplora la "nuvola delle parole (Word Cloud) per avere un'idea di massima del progetto.

 Obiettivo del progetto (Objective)

'The main objective of the project is to develop a new aluminium wrought alloy that can work at temperatures in the range of 200-250ºC for aeronautical applications such as regulator valves or actuator bodies for air treatment systems. Several heat resistant aluminium based materials have already been developed in the last years that might be applied for such high temperature applications. Notwithstanding, these are either too expensive or present additional technical drawbacks such as insufficient ductility, segregation of components, low machinability or recycling problems. The present project aims at developing new alloys through a methodology based on the identification of the effect of up to 12 alloying elements and their combinations in the heat resistance of wrought alloys through the Taguchi methodology. This is based on the selection of critical parameters through design of experiment techniques that minimise the time and resources to be employed in the process. Two orthogonal matrices are to be used, a L16 matrix and a modified L8 matrix. The former employs two levels that are related to the maximum and minimum amounts of the alloying element. The modified matrix incorporates intermediate values. In a first stage gravity casting samples with 24 different formulations are cast by gravity casting and preliminarily tested in order to check whether any of these combinations may reach the established specifications Subsequently, the most promising 2 alloys would be further developed.

Researchers belonging to the non ferrous metallic materials and characterization departments of Tecnalia will lead the project. Their work will be complemented by the researchers at Fundación Inatec, a research institution that is part of the Otua industrial group related to recycling and recovery of metals and Refial, a company devoted to the production of aluminium alloys. They will be responsible of the cost analysis issues, environmental aspects and industrialisation aspects.'

Introduzione (Teaser)

Lightweight aluminium (Al) alloys are an important pillar of aircraft development. With predicted future service conditions requiring higher operating temperatures, scientists explored new wrought alloys and thermal treatments to improve properties.

Descrizione progetto (Article)

Wrought alloys are ingots or billets made for subsequent hot and or cold casting processes. Wrought Al alloys are known for their high strength and easy workability to create the desired final forms. The EU-funded project ALT was initiated to identify novel wrought Al alloys for high-temperature applications.

The consortium brought together two research institutions, one studying non-ferrous metallic materials and their characterisation and the other investigating the recycling and recovery of metals. An Al alloy manufacturer rounded out the technical research with a study of cost, environmental aspects and industrialisation.

Scientists selected 24 different formulations of alloying elements and their combinations using the Taguchi method for factorial design of experiments. The wrought alloy ingots were extruded and samples were then tested for heat resistance. This methodology determines the minimal number of experiments required to provide full information about all factors affecting the performance parameter. Its goal is a high-quality product at low cost to the manufacturer. Promising preliminary results of tensile properties at both room temperature and 250 degrees Celsius led to selection of two formulations for further testing. Both were Al-copper (Cu) alloys differing in Cu content.

During the second year, the two most promising candidates were subjected to tests of formability, recyclability, creep and tensile strength. In general, the Al-Cu alloys performed well, comparably to other alloys. The optimised heat treatment improved mechanical properties.

After a 1 000-hour ageing process at 250 degrees Celsius, the strength was also slightly higher than most other conventional alloys except for one premium wrought alloy and one casting one. However, the maximum foreseen strength was diminished due to formation of a continuous phase in the grain boundaries and the alloys are more expensive than the reference alloy. Potential future investigations could focus on modifications to the heat treatment to further increase mechanical properties at high temperature.

ALT conducted a comprehensive evaluation of promising Al alloys for future aircraft components exposed to high-temperature operating conditions. Deeper understanding of the behaviours of these alloys produced by ingot metallurgy points the way to future research directions to improve mechanical properties while reducing costs.