Product category:
Materials processing and testing
News Release from: Corus Automotive
Edited by the Engineeringtalk Editorial
Team on 26 January 2007
Novel brazing technique joins steel to
aluminium
Corus, the international steel company, has developed Fluxless Laser Brazing, a new and robust process for joining steel to aluminium during automotive production line assembly.
Corus, the international steel company, has developed Fluxless Laser Brazing, a new and robust process for joining steel to aluminium during automotive production line assembly The new technique has been developed at the Corus RD and T centre in Holland, to support the automotive industry's increasing use of multimaterials in new car design and manufacture, as a way of reducing weight and improving CO2 emissions
Although reducing weight to improve CO2 emissions remains one of the main drivers in the global automotive industry, the need to lightweight is balanced against the need to keep manufacturing costs down.
Thanks to its performance and cost benefits, there is little doubt that steel will remain the material of choice for main vehicle body structures in volume car production.
However, automotive designers are substituting steel for aluminium for specific applications, such as the bonnet and roof, where advantages beyond weight reduction, such as weight distribution for optimum ride and handling, can be achieved.
Until now though, the welding of steel to aluminium has been a complicated process and one that poses specific challenges to vehicle manufacturers.
For example, when the two different materials are welded together, it results in a thick intermetallic layer, which can result in a brittle and weak weld joint, clearly not suitable for any automotive application.
Controlling the heat input using laser based welding techniques has been one way of reducing the thickness of this intermetallic layer.
However, traditional laser welding methods require the use of a salt-based flux to enable a joint to be created.
This is not without problems, as a salt-based flux is more prone to expose the joint to corrosion.
The new process removes the need to apply a flux during the welding process which, Corus believe, will help take significant costs and time out of the manufacturing process.
In addition, removing the salt-based flux also removes the potential source of weld corrosion.
The Fluxless Laser Brazing process works by applying an aluminium-based filler wire to create a weld on the aluminium side of the joint.
The molten filler metal then 'wets' the steel creating a 'brazed joint' on the steel side of the weld.
Importantly, tests have shown that this new technique creates only a very thin inter-metallic layer making it possible to create joints that are, in some cases, stronger than the base materials themselves.
Jurgen Vrenken of Corus RD and T said: "The development of our unique Fluxless Laser Brazing technique is another example of how we combine material knowledge with engineering expertise to offer vehicle manufacturers practical, low cost mass produced vehicle design solutions".
"We believe our new welding process is ideally suited to joining aluminium components, for example a roof, into a steel body-in-white, offering vehicle manufacturers further options for saving weight beyond the use of advanced high strength steels". Request free introductory details about products from Corus Automotive ...
• Corus Automotive: contact details and other news
• Email this article to a colleague
• Register for the free Engineeringtalk email newsletter
• Engineeringtalk Home Page
Search the Pro-Talk network of sites
