The optimization of friction spot welding process parameters in AA6181-T4 and Ti6Al4V dissimilar joints

• Friction spot welding of AA6181-T4/Ti6Al4V single-lap joints was demonstrated.
• The influence of joining parameters on joint mechanical performance was determined.
• A mathematical model for estimating lap shear strength was successfully established.
• A set of welding parameters was obtained to produce economic and efficient joints.

Friction spot welding is a relatively new solid-state joining process able to produce overlap joints between similar and dissimilar materials. In this study, the effect of the process parameters on the lap shear strength of AA6181-T4/Ti6Al4V single joints was investigated using full-factorial design of experiment and analyses of variance. Sound joints with lap shear strength from 4769 N to 6449 N were achieved and the influence of the main process parameters on joint performance was evaluated. Tool rotational speed was the parameter with the largest influence on the joint shear resistance, followed by its interaction with dwell time. Based on the experimental results following response surface methodology, a mathematical model to predict lap shear strength was developed using a second order polynomial function. The initial prediction results indicated that the established model could adequately estimate joint strength within the range of welding parameters being used. The model was then used to optimize welding parameters in order satisfy engineering demands.

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