￼42<< MATERIALS Figure 6. a. Execution of the P10.2 segment of the P10 FSW test joint; b. The P10 test joint after the FSW joining operations. Figure 6 presents the FSW/P10 test joint after the FSW joining ope- rations. The temperature in not very uniform, but the amplitude of these variations are within the allowed limits of 460-530 oC, respec- tively 70-80% of the melting temperature of the aluminium alloy. The in uence of these variations upon the mechanical characteristics was analyzed and the plastifying level is considered as adequate. The FSW welding process was carried out under normal conditions. By the visual examintion after each pass, it is found that the joint seg- ments performed by the FSW process on the P10 test joint sample have an appropriate appearance. There is no welding aw on any segment. At the macroscopic examination (Figure 7), with a magni cation of maximum 50 times, in accordance with SR EN ISO 25239-5: 2011, of this FSW lap joint, there are copper whiskers, which penetrate into the aluminum alloy, as well as very small aluminium whiskers in copper, both realizing the joint. There are some small cavities that are below the acceptance limit speci ed in the standard, as punctiform round welding imperfections. Incomplete thickness is found, that is approximately 10% reduction of the thickness of the copper sheet, placed above, caused by the friction motion of the FSW tool. This reduction in thickness is justi ed and accepted. It is taken into account when designing this dissimilar joint, depending on its use. Table 1 shows the results obtained by the tensile test (of the test joints 1, 2 and 3). Figure 7. The macroscopic aspect of a FSW joint, on a specimen. The tensile strength of the specimens is in the range 42.41 – 93.37 N/ mm2. The dispersion of these amounts is explaned by the width of the joint that has not the same extent along a joint, nor in a joint compared to another one. The tensile strength depends on the pecentage participation of each base material, intermetalic compounds, oxides, other structural cons- tituents and aws in the cross section of the weld. The obtained results are adequate for the welds of the material classes used in these cases. In the table 4.5, the results obtained by the shear test (of the test joints 1, 2 and 3) are shown. The maximum working temperature of the tool depends on the type of steel used to make them Ultimate Specimen tensile force Fm(N) 1.3.2 6961.72 2.1.1 4545.66 2.2.2 6230.52 2.3.1 4264.15 3.1.1 3988.66 3.2.1 4710.19 3.3.1 5048.96 Specimen Joint width width a (mm) b0(mm) 0 15.00 4.97 14.90 4.90 14.90 5.19 15.00 3.43 15.00 6.27 15.00 5.90 15.00 6.84 Cross section S0(mm2) 73.95 68.60 77.33 51.45 94.05 88.05 102.60 Ultimate tensile strength Rm (N/mm2) 93.37 66.85 80.60 82.90 42.41 53.22 49.20 Table 1. Results obtained by the tensile test (of the test joints 1, 2 and 3).