TWI Industrial Member Report Summary 683/1999
A J Leonard
Background
Friction stir welding (FSW) of aluminium alloys is now an established joining technique. One of its benefits is that it is a solid state process, and therefore capable of producing high quality joints in aluminium alloys that were previously difficult to weld using fusion welding techniques, for example 2xxx and 7xxx series alloys.
The method uses friction, generated by a specially profiled non-consumable rotating tool in contact with the surfaces to be welded, to heat and soften the metal at the interface to be joined. The rotating action of the tool then transports materials from in front of the tool to the rear, mixing and forging it, creating the welded joint.
Earlier microstructural work has demonstrated that the thermomechanical processing in the weld region results in a series of distinct microstructures, there is therefore a need to understand the microstructural development of aluminium alloy friction stir welds if the technology is to be fully exploited.
Whilst many studies have been carried out on the mechanical properties of friction stir welds, only limited studies have been concerned with the corrosion of such joints. There is, therefore, a general requirement also to determine the performance of aluminium alloys friction stir welds in various corrosive environments.
Objectives
- To determine the development of microstructures in a range of aluminium alloy friction stir welds.
- To determine the corrosion performance of weldments.