30 September 2010
EADS technologies available for licensing opportunities in the areas of aluminium-magnesium-scandium (AlMgSc) alloys and the friction-stir welding process were outlined today in an on-line webinar attended by an international audience.
Organized with the assistance of yet2.com – a U.S.-based company with an on-line global marketplace for intellectual property – the webinar’s first focus was on EADS’ DeltaN tool for friction-stir welding, which is a solid state joining process that creates a uniform joint through the heating of material by frictional heat, with stirring created by a rotating pin.
The webinar’s other topic was EADS’ capabilities with its first-generation AlMgSc technology for sheet material (associated with integrated creep forming and laser beam welding production techniques), along with the company’s second-generation AlMgSc Scalmalloy® alloy for extrusion-produced profiled parts.
Juergen Silvanus, an expert in new joining technologies at EADS Innovation Works – the company’s worldwide network of dedicated research centres – said innovative friction-stir welding techniques and tools have been in development at EADS for 12 years. These techniques were pursued with the goal of providing high-quality welding on thick welded sections (thicker than 6 mm.) for integral structures.
“The problem in applying friction-stir welding on thick sections is the inhomogeneous heat distribution that occurs from the top side to the root side of the welded sheet or plate,” he explained.
EADS’ response to this challenge was the development of a welding tool, called DeltaN, which has a stationary shoulder portion and a rotating welding pin. The heat input introduced by the DeltaN tool into the welded part is significantly reduced, and the tool creates a nearly fully-symmetrical heat input throughout the welded section’s thickness.
EADS’ extensive work on innovative friction-stir welding techniques and tools resulted in the development of its DeltaN tool, which reduces welding distortion and vertical down-forces, while creating a nearly fully-symmetrical heat input throughout the welded section’s thickness.
“Compared to standard friction-stir welding process, the welded alloy’s remaining strength can be significantly higher when the DeltaN welding tool is used, and distortion after welding is significantly reduced,” Silvanus said.
EADS’ work with DeltaN has validated its advantages, which include a reduction of welding distortion by a factor of eight when compared with a typical standard tool, along with a reduction in vertical down-force by a factor of two.
In addition, DeltaN is based on a simple – and therefore robust – design, and its higher level of revolutions increases lifetime of the tool’s pin by reducing lateral loads. Silvanus said DeltaN has an impressive range in welded sections, with the company already demonstrating its capabilities on sheets with thicknesses from 0.3 mm. to 25 mm.
An important advantage in using the DeltaN tool is the superb surface appearance it provides on the weld crown side. Additionally, the tool can reduce post-weld machining – which is a cost-driver and involved time-consuming work.
“There is growing interest in the DeltaN, and EADS is open to working with partners on the transfer know-how for this tool’s application,” Silvanus added. “This can include the development of related production processes; for example, we have robotised the process using a highly cost-effective and flexible articulated robotic arm.”
Frank Palm, a Senior Expert in welded structures and processes at EADS Innovation Works, said AlMgSc technology offers many advantages in the high-strength applications of aluminium alloys.
“These advantages include reduced weight and improved durability, as well as significantly improved protection against corrosion fatigue and stress corrosion cracking – which are show-stoppers for all high performance aluminium alloy applications,” he explained. “In addition, the use of AlMgSc alloys will minimise the VOCs (volatile organic compounds) and other hazardous agents that are required for the surface conditioning and protection of all high-strength aluminium alloys.”
Both the first-generation AlMgSc technology available from EADS and its second-generation Scalmalloy® provide robust solutions for the use of aluminium alloys when high specific strength and exceptional high corrosion resistance are desired – while also offering the additional advantages of robust manufacturing chains and low-cost production schemes. Additionally, they have the highest micro-structure material stability for “low carbon footprint” applications.
The EADS-developed Scalmalloy® alloy is tailored for high- and very high-strength extrusions. It provides a material with exceptional high-fatigue properties,and which is strength- and density-adaptable.
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