Aluminum alloys Friction Friction stir spot welding Friction stir welding Spot welding Welds aluminium alloy Backpropagation Computer software Correlation coefficient Feed-forward back propagation Feedforward neural networks Finite element method Forecasting Full factorial design Highest temperature Hyperworks software Iterative methods Learning systems Load testing Machine learning techniques Multilayer neural networks Neural networks Parameters selection Property predictions Rotational speed Solid-state joining Solid-state welding Speed Spindle speed