Under tensile shear loading, fracture modes of dissimilar lap welds produced by friction stir scribe technology were studied. Three fracture modes were observed. For zone A fracture, the initial crack was restrained, and the joint ultimately fractured in the base mild steel. For zone B fracture, the initial crack progressed through the aluminium sheet just above the Al/steel interface. For zone C fracture, the initial crack proceeded along the steel hook to the aluminium sheet surface. Fracture mode and joint strength were greatly influenced by steel hook size, and the steel hook size was affected by welding parameters and tool scribe height. In this study, the experimental joint strength achieved the calculated joint load limit.

Friction stir scribe technology, a derivative of friction stir welding, was applied for the dissimilar lap welding of an aluminium alloy and galvanised mild steel sheets. During the process, the rotating tool with a cobalt steel scribe first penetrated the top material – aluminium – and then the scribe cuts the bottom material – steel. The steel was displaced into the upper material to produce a characteristic hook feature. Lap welds were shear tested, and their fracture paths were studied. Welding parameters affected the welding features, including hook height, which turned out to be highly related to fracture position. Therefore, in this paper, the relationships among welding parameters, hook height, joint strength and fracture position are presented. In addition, the influence of zinc coating on joint strength was also studied.

This research used a discrete event simulation to create data on a shipment receiving process instead of using historical records on the process. The simulation was used to create records with different inputs and operating conditions and the resulting overall elapsed time for the overall process. The resulting records were used to create a set of predictive artificial neural network models that predicted elapsed time based on the process characteristics. Then, the connection weight approach was used to determine the relative importance of the input variables. The connection weight approach was applied in three different steps: (1) on all input variables to identify predictive and non-predictive inputs, (2) on all predictive inputs, and (3) after removal of a dominating predictive input. This produced a clearer picture of the relative importance of input variables on the outcome variable than applying the connection weight approach once.

Reports in the literature indicate that temperature control in Friction Stir Welding (FSW) enables better weld properties and easier weld process development. However, although methods of temperature control have existed for almost two decades, industry adoption remains limited. This work examines single-loop Proportional-Integral-Derivative (PID) control on spindle speed as a comparatively simple and cost-effective method of adding temperature control to existing FSW machines. Implementation of PID-based temperature control compared to uncontrolled FSW in AA6111 at linear weld speeds of 1–2 m per minute showed improved mechanical properties and greater consistency in properties along the length of the weld under temperature control. Additionally, results indicate that a minimum spindle rpm may exist, above which tensile specimens do not fracture within the weld centerline, regardless of temperature. This work demonstrates that a straightforward, PID-based implementation of temperature control at high weld rates can produce high quality welds.