LIke other metallic materials, magnesium alloys can be joined using bolting, riveting, welding, screwing and adhesive bonding.
When bolting magnesium alloys together, thick washers should be used under bolt heads and nuts to avoid damaging the flange or spot face. Screwed threads should be coarse, with flat or rounded tops to avoid the notch effect. Magnesium alloys can be joined by riveting, but care must be taken not to crack or deform the magnesium around the rivet holes by using incorrect rivet lengths, applying too much force or using incorrect dollies.
If the components are expected to be used in a severe atmosphere, protection against galvanic corrosion must be considered with all the joining methods. Welding magnesium is generally performed using the inert gas tungsten arc (TIG) or argon arc techniques As there is no flux involved, there is no risk of flux entrapment causing subsequent corrosion of the welded joint. The tensile strength of an undressed butt weld made by the argon arc process usually exceeds 90% of that of the parent material in the unannealed state. Postweld heat-treatment to relieve residual stresses should follow unless the magnesium casting has to be heat-treated at a higher temperature to meet the relevant specification for the parent metal.
Please see attached 'Joining of Magnesium.PDF' for further details, including a table of recommended heat-treatment schedules for the welding of magnesium casting alloys such as Elektron ® RZ5 (ZE41) and Elektron ® WE54.
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