Effects of welding current, arc length and shielding gas flow rate on arc pressure

Gas tungsten arc (GTA) welding was performed on a water-cooled copper plate with a 1mm hole at the center of the surface. The pressure in the hole was measured using a digital pressure sensor. The electric arc current was varied between 80A and 150A, and the argon shielding gas flow rate was between 31/min and 251/min. The arc length was between 1mm and 8mm. The polarity was direct current electrode negative (DCEN). Both upward and downward welding was performed. As the electric current decreases, the arc pressure also decreases, but it is constant at 200Pa between 80A and 120A under the conditions of a 3mm arc length and 51/min flow rate. When the shielding gas flow rate increases, the arc pressure is constant even for a higher electric current. When the current is less than 100A, the pressure is constant at 200A even when the arc length decreases to 1mm. When the current is greater than 130A, on the other hand, the arc pressure is higher, as the arc gap gets shorter. However, the pressure is 200Pa for the larger arc lengths. Accordingly, it can be concluded that 200Pa is derived from near the anode area. When the, shielding gas increases, the effect of plasma stream is negligible for a larger welding current.