Alcan International Limited

Warren Hepples

Geoffrey M Scamans

Nigel J Holroyd

Problems are caused by stress corrosion cracking and exfoliation cracking in the heat-affected zones adjacent welds in structure of welded components formed of Al alloys, particularly of the 7000 series but also of the 5000 series. The invention seeks to overcome these by the use of Al-Mg welding wire containing 0.01-0.5% Ga and/or In and/or Sn, the composition being chosen such that the weld bead has a potential at least as electronegative as the components and preferably in the range -1200 to -1300 mV with reference to a standard calomel electrode. To prevent diffusion of Ga/In/Sn, the components may be pre-coated e.g. by using a double-pass welding technique.

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Oxon, United Kingdom

Warren Hepples