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Development of magnesium technology from billet casting to profile manufacturing

Development of lightweight, high-performance magnesium alloys
for the automotive, electronic/ aerospace industries with
maximum extrusion speed, meeting performance requirements/
considerable environmental benefits.

Having a gravity only about 1/4 of that of iron and steel and 2/3 of that of aluminium, magnesium is the lightest structural metal on earth. This feature presents a much greater weight-saving potential compared to aluminium, when substituting cast iron and steel, to fulfil the need of the European automotive industry that has committed itself to reducing fuel consumption by 25% and CO2 emissions by 50% by 2005 in comparison with the levels in 1990. (A 10% reduction in vehicle weight can bring about a reduction of fuel consumption of about 5%). In recent years magnesium consumption has grown by 15% per year and this rate is expected to be sustainable for many years to come, as the automotive, electronic and aircraft industries keep moving towards lightweight solutions for environmental protection, fuel economy, payload and downsized structures. The development of magnesium alloys in the last 10 years has been concentrated in cast alloys and their applications in automobiles. At the moment, over 95% of automotive structural components made of magnesium are manufactured through die-casting. This abnormal ratio must change by increasing the market share of extruded magnesium alloys. However, before the great potential of extruded magnesium profiles can be explored, many technical barriers must be overcome. The present project is intended to address the technical problems spread over the whole chain of profile manufacturing and to find commercially viable solutions, so as to provide extruded magnesium products with strong competitive advantages. The project is targeted: - To produce extruded profiles made of existing wrought magnesium alloys with a 25% higher strength and ductility in comparison with their cast counterparts. - To produce new extrusion alloys with mechanical properties at the same level (specific strength and ductility) as medium-strength aluminium alloys suitable for structural applications. - To adapt Direct-Chill (DC) casting for aluminium to magnesium billet preparation, to minimise the use of Hexafluoride Gas (SF6) as protective atmosphere and to cast billets with grain size at least 50% smaller than that from pressure die casting (ca. 200/m) without surface and internal defects. - To develop the method of homogenisation treatment to modify the as-cast structure and allow extrusion speed to increase by 50% in comparison with no homogenisation (3m/min). -To develop magnesium extrusion techniques to reach a scrap rate less than 25% (equivalent to the level of technologically advanced aluminium extrusion plant in western Europe), an extrusion speed at least 50% higher than the current level (3 m/min) and a die correction rate not more than 1.5 times for each profile (current level in the European aluminium extrusion industry: 1.7 trials for each new die on average). - To develop new die materials with die service life increased by 100% in comparison with the conventional H13 hot-work tool steel. - To develop special multi-wavelength pyrometers to be able to quickly and accurately measure the temperature of magnesium billet moving into the container and the temperature of extruded magnesium profile leaving the press mouth. - To establish the correlation between the mechanical properties of the extruded profiles/ ageing condition and to be able to tailor treat magnesium profiles according to their property specifications. To reach these targets, theoretical studies will be coupled with experimentation in the laboratory and in the industrial setting. Emphasis will be placed on the establishment of industrially applicable knowledge and methodology, thereby formulating guidelines for the tailor- design of magnesium alloys for extrusion, the selection of process parameters and the design of extrusion dies to meet the demands for a wide range of applications of magnesium profiles after the completion of the project. The project is broadly divided into three phases. Each phase has a definitive list of tasks. Each task has clear objectives and responsibilities that each partner takes on and deliverables (results): * Phase I concerns the first round of developing the processing technologies from DC casting through extrusion to heat treatment. The magnesium alloys dealt with in this phase are those of general-purpose wrought magnesium alloys. The results of the investigations in this phase are expected to provide the hardware, knowledge and methodology for the next phase and also the reference process conditions and material properties. * Phase II concerns the development of new magnesium alloys especially suitable for extrusion and the second round of developing the processing technologies from DC casting through extrusion to heat treatment. The results of the investigations in this phase are expected to provide convincing data about the performance of extruded profiles processed via a cost-effective route for market exploitations. * Phase III comprises two aspects. On the technical front, it concerns the compilation of material data and processing data for further development and on the economic front, it concerns an objective analysis of material costs and processing costs for commercial exploitations. The project will in the end bring a variety of magnesium profiles with strong competitive advantages to the market for a wide range of applications in the automotive, electronic and aerospace industries. In addition, it will foster the supporting industries for magnesium profile manufacturing, including billet casting, die-making and process control. Keywords: magnesium, casting, extrusion.
Acronym: 
DEMAT
Project ID: 
2 756
Start date: 
01-05-2002
Project Duration: 
72months
Project costs: 
5 900 000.00€
Technological Area: 
Metals and Alloys
Market Area: 

Raising the productivity and competitiveness of European businesses through technology. Boosting national economies on the international market, and strengthening the basis for sustainable prosperity and employment.