TWI Frequently asked questions
It is not possible to friction stir weld steel to aluminium using conventional approaches at this time because the temperature at which aluminium softens is much lower than that of steel, so that aluminium would be molten beforesteel was soft enough to friction stir weld. Success has been demonstrated by using an offset in the tool path, such that the edge of the tool just makes contact with the steel and removes the oxide, allowing metal to metal contact andhence joint formation. The low temperatures reached will restrict intermetallic formation. This approach is still experimental. Certain aluminium alloys can be joined to steel by other friction based processes (rotary, linear etc.),and also by friction plunge welding.
TWI should be consulted to discuss specific applications.
