When a world-famous aircraft manufacturer sought reduced fabrication costs to join its aluminium alloy parts it came to TWI for some of the answers.
More specifically, it was interested in linear friction welding as a way of lowering what it called its buy/fly ratio, the difference between the cost of raw materials and turning them into operational flying components.
TWI's requested objectives were to develop welding procedures for linear friction welding of AA7050-T7451 that had been subjected to a variety of thermo-mechanical processing operations, and to produce several dozen samples fortesting and evaluation by the client.
Unlike the client, TWI owns three high-powered linear friction welding machines. In the last decade they've been used to join titanium, stainless steel, aluminium, mild steel, and many nickel-based super alloys.
The client asked that a series of trial welds was made specifically to determine the optimum welding parameters needed for high quality welds between sample blocks of AA7050 material provided by the client.
Five variables were considered: the friction and forge pressures, the burn-off, amplitude and frequency. Armed with these values for 72 welds, TWI was then asked to test their performance visually, metallographically and by tensiletesting.
TWI was able to assure the client; first, that high-integrity bonded interfaces were achieved in the experimental welds, and second, that the supplied material, which had been subjected to a 2% stretch before welding, required ahigher forge force than unstrained material.
To learn more about TWI's friction welding capabilities in a variety of materials and applications, particularly aerospace, call Kathryn Beamish or Mike Nunn at Abington.
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