*2.1. Base Metal and Filler Wire Materials*

In order to be as reliable as possible, the analyses were carried out on samples machined from a prototype of an actual sports car frame composed of different aluminum alloys welded together. It is worthwhile noting that the opportunity to study actual automotive parts is extremely relevant to evaluate the real quality of the welds, especially considering that the automotive sector is highly demanding in terms of both market rules and safety regulations. Another relevant topic is the presence into the frame of joining between both wrought and cast alloys such as EN-AW 6181-T6, EN-AW

6082-T6, and EN AC 42100-T6. At the same time, in order to complete the research activity, samples were appositely made to reduce the data variation that could arise from a real frame investigation. In particular, extruded and casting bars were used to realize the same different combinations of the frame (EN AW-6181-T6 and EN AC 42100-T6).

During the welding, we used an additional UNI—ER 4043 (AlSi5) filler wire with a diameter of 1.2 mm to minimize either the porosity, the notching, or the cracking susceptibility of the joint. The chemical compositions of the base and filler materials selected in this study are reported in Table 1.


**Table 1.** Chemical composition of aluminum alloys.
