State of the art about dissimilar metal friction stir welding

ABSTRACT

Friction stir welding is a rather recent welding process (patented in 1991 by Thomas et al., ‘Improvements to friction welding’ UK patent application no. 9125978.8, US Patent 5460317, 1995) that has shown great potential for welding dissimilar materials even of different metallic nature, e.g. Al to steel, Mg to steel, Al to Ti, Mg to Ti, Al to Cu, Al to Mg. This review presents the specific microstructural features and mechanical properties, in particular tensile strength, of such welds. A focus will be on the material flow and welding defects, on the intermetallic compounds, on constitutional liquation, on particularities related to dissimilar lap welding and finally on process modifications to improve dissimilar friction stir weldability.

KEYWORDS:

• Friction stir welding
• dissimilar welding
• aluminium
• copper
• magnesium
• steel
• titanium

Acknowledgements

A. Simar acknowledges the financial support of the IAP Program from the Belgian State through the Belgian Policy Agency, contract IAP7/21 ‘INTEMATE’. The authors have interacted as part of the SF2M-AFM commission on FSW. N. Jimenez-Mena is thanked for making Figure 1.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 Firouzdor et al. [32] measured the temperature at 3 mm from the weldline for Al6061 to AZ31B welds when increasing the rotational speed from 1400 to 2200 rev min⁻¹ for an advancing speed of 38 mm min⁻¹. They found typically a 45C increase in temperature. When increasing the advancing speed from 38 to 254 mm min⁻¹ at 1400 rev min⁻¹, the decrease in temperature was between 15 and 50C.