**2. Basic welding parameters**

The welding arc is formed by the arc plasma, which consists of ionized gas, molten metals, slags, vapors, and gaseous atoms and molecules. Arc welding variables are welding current, are voltage, welding speed, shielding gas and filler metal that cause much more effect on various weld joint properties such as strength, weld bead geometry, cooling rate and corrosion of stainless steel.

#### **2.1 Welding current**

Welding current is the most important variable affecting melting rate, metal deposition rate, depth of penetration, width of joint and the amount of molten base metal. The electrical energy can be calculated by Eq. (1) [8]:

$$\mathbf{Q} = \mathbf{I} \ast \mathbf{V} \,\mathbf{J} / \mathbf{S} \,\text{or}\,\mathbf{Q} = \mathbf{I}^2 \ast \mathbf{R}\_\mathbf{a} \,\mathbf{J} / \mathbf{S} \tag{1}$$

where, Q = Consumed electrical energy I = Welding current.

V = Arc voltage Ra = Arc resistance.

The influence of welding current on AISI 316 welded by GTA was studied [9]. UTS and HV increased with increasing heat input. Best results for UTS and HV were

obtained using 100A. Also, sigma phase and Cr23C6 in 316 SS welded samples increased with increasing heat input as shown in **Figures 1**–3.
