**2. Materials and methods**

Here, the dissimilar welding of the joints was carried out using friction stir welding machine 3 T/HYD machine. **Figure 1** shows the schematic representations of the dissimilar friction stir welding process. The tool was plunged into the weld centerline for the production of the frictional heat and plastic flow. Using the above process parameters, the aluminum plates were joined together by extreme thermo-mechanical conditions to alter the microstructure of the welding. The AA7075 and AA2014 alloys

*Center Stir Zone Investigations of Dissimilar AA6082, AA2014 and AA7075 Welds DOI: http://dx.doi.org/10.5772/intechopen.102652*

#### **Figure 1.** *Friction stir welding process.*


#### **Table 1.**

*Chemical composition of the alloys.*

were placed in the retreating side, AA6082 was placed in the advancing side to obtain better property in the weldments.

The materials AA7075-T6, AA6082-T6, and AA2024-T6 chemical compositions are in **Table 1**. **Table 2** illustrates the mechanical properties of the alloys. **Table 3** is illustrating process parameters used for dissimilar FSW of AA7075, AA6082, and AA2024. **Figure 2** is showing the welded samples of the dissimilar alloys. Then, the as welded samples were prepared to carry out testing. Further the tensile tests were carried out as per ASTM E 384-99. Then, for the microstructure studies the specimens were prepared using consecutive 220, 400, 600, and 800 grade emery paper, and followed by cloth polishing. After that the specimens were etched with freshly prepared Keller's reagent of solution containing 190 ml water, 5 ml HCL, 3 ml HF, and 2 ml HNO3. And the microstructures were taken using METZER microscope.


**Table 2.** *Mechanical properties of alloys.*


**Table 3.**

*FSW process parameters used.*

**Figure 2.**

*Dissimilar FSW samples. (a) AA6082&2014, (b) AA6082&7075, and (c) AA2014&7075.*

The microhardness readings were carried out using a MATSUZAWA MMTX3 microhardness tester with 300 gm of weight at 15 seconds of dwell time. The grain orientation and its size were studied using EBSD analysis. So as to carry out EBSD analysis, the samples were emery polished and electro polished to 100 μm thick to carry out EBSD scans using SEM-FEI Quanta with TSL-OIM software.
