**2. Materials and process**

Workpieces with 25 mm width and 100 mm length are prepared from joining sheets. The chemical composition and mechanical properties of the studied sheet are presented in **Tables 1** and **2**, respectively. The workpieces in a lap position are installed on the machine, designed for doing the FSSW and FSSVW, while the thin one is on top. The schematic view of this machine is presented in **Figure 1**. The machine is fixed on the milling machine table.

According to **Figure 1**, the workpiece vibration is applied through a fixture. The motor shaft rotation is transformed into the linear and reciprocating movement of the fixture by a camshaft mechanism. The vibration amplitude is adjusted to be 0.5 mm. An AC motor with 0.5 kW power is used for FSSVW. Motor shaft speed which controls the vibration frequency is adjusted using a driver. A non-consumable tool (**Figure 2**), consisting of the pin, from carbide tungsten, and shoulder, from M2 heat-treated steel, is used for welding processes. The welding tool was rotated in the clockwise direction during the welding process.


#### **Table 1.**

*Chemical composition of base metal (wt%).*


#### **Table 2.**

*Mechanical properties of base metal.*

**Figure 2.** *a) the geometry and, b) the design of pin and shoulder utilized for FSSW and FSSVW processes.*

During the FSSVW process, different vibration frequencies are implemented to investigate the effect of vibration frequency on microstructure and mechanical characteristics. **Table 3** shows the welding condition for different welded samples.

Metallography techniques based on ASTM are used to reveal the microstructure of weld regions. Mounted samples were ground by rotating discs of abrasive paper of silicon carbide and then were polished and etched. The linear intercept method (ASTM-E112-13) is applied to measure the grain size. Shear tensile test according to ANSI/AWS/SAE/D8.9-97 is used to obtain lap shear strength-displacement curves of welded specimens. For each welding condition, four specimens are tried. Vickers micro-hardness method based on ASTM-E384 is applied to assess the hardness. For hardness tests, the load is 300 gf and the dwell time is 10 s. For each welding condition, 4 data are measured.


**Table 3.**

*Welding conditions for different welding trials (+ donates FSSVW and − donates FSSW).*

*Study on Microstructure Evolution and Mechanical Properties of Al5083 Joint Obtained… DOI: http://dx.doi.org/10.5772/intechopen.102082*
