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A study examining the fatigue behaviour of spot friction stir joined (SFJ) aluminium NG5754 and AA6111 sheets was carried out. Different friction stir holding times were applied to the NG5754 alloy, whilst paint bake cycles were applied to the AA6111 joints in order to examine the effects of these variables on the fatigue behaviour of the joints. Static and fatigue tests were performed on all samples and the results were compared. It was demonstrated that the material flow characteristics were affected by the holding time leading to different joint attributes, which in turn contributed to different fatigue behaviour. Paint bake cycle affected the fatigue life, particularly at low applied loads.

A study examining the effect of coatings on the quality and behaviour of self-piercing riveted joints joining aluminium NG5754 to HSLA350 sheets was conducted. Two types of coatings: E-coated and Zinc plated were applied to the HSLA350 sheet for this study. The results showed that coating affected the joint quality in terms of head height, interlock and remaining material thickness. Examination of joint sections indicated that the self-piercing riveting process needed different setting parameters for coated and uncoated sheets in order to achieve optimum setting conditions. The joint strength was also affected by sheet coatings. However, whether the joints with coated sheet had higher strength was dependent on joint setting conditions. Different coatings had different effects on joint quality and behaviour and different setting conditions led to different behaviour of the joints with or without coatings.