The welding current of argon tungsten arc welding is usually selected according to the material of the workpiece, the thickness and the spatial position of the joint. When the welding current increases, the penetration depth increases, and the width and residual height of the weld increase slightly, but the increase is very small. Too large or too small welding current will cause poor weld forming or welding defects.

The arc voltage of argon tungsten arc welding is mainly determined by arc length. As arc length increases, arc voltage increases, weld width increases, and penetration depth decreases. When the arc is too long and the arc voltage is too high, it is easy to cause incomplete welding and edge biting, and the protection effect is not good.
However, the arc can not be too short, the arc voltage is too low, the arc is too short, the wire is easy to touch the tungsten pole to cause short circuit, so that the tungsten pole is burned, and it is easy to clip tungsten, so the arc length is usually approximately equal to the diameter of the tungsten pole.

When the welding speed increases, the penetration depth and width decrease, when the welding speed is too fast, it is easy to produce non-fusion and non-penetration, and when the welding speed is too slow, the weld is very wide, and it may also produce defects such as welding leakage and burning through. In manual argon tungsten arc welding, the welding speed is usually adjusted at any time according to the size of the molten pool, the shape of the molten pool and the fusion on both sides.

1. Nozzle diameter
The nozzle diameter (refers to the inner diameter) increases, the protection gas flow should be increased, and the protection area is large and the protection effect is good. However, when the nozzle is too large, it not only increases the consumption of argon, but also makes it difficult to observe the welding arc and welding operation. Therefore, the nozzle diameter usually used is generally 8mm ~ 20mm.

2. Distance between nozzle and weldment
The distance between the nozzle and the weldment refers to the distance between the nozzle end face and the workpiece, the smaller the distance, the better the protection effect. Therefore, the distance between the nozzle and the weldment should be as small as possible, but too small will not be easy to observe the molten pool, so the distance between the nozzle and the weldment is usually 7mm ~ 15mm.

3. Tungsten electrode extension length
In order to prevent the arc from overheating and burning the nozzle, the tungsten extreme part should usually extend out of the nozzle. The distance between the tungsten extreme head and the nozzle end is the tungsten electrode extension length, the smaller the tungsten electrode extension length, the closer the distance between the nozzle and the workpiece, the better the protection effect, but too small will prevent the observation of the molten pool.
Generally, when welding the joint, the tungsten electrode extension length of 5mm ~ 6mm is better; When welding fillet weld, tungsten electrode extension length of 7mm ~ 8mm is better.

4. Gas protection mode and flow rate
In addition to using a circular nozzle to protect the welding area, the nozzle can also be made into a flat shape (such as narrow gap argon tungsten arc welding) or other shapes according to the welding space. When welding root welds, the welds on the back of the welds will be oxidized by air pollution, so the back inflation protection must be used.
Argon and helium are the safest gases to inflate the back of all materials when welding. Nitrogen is the safest gas to protect the back when welding stainless steel and copper alloys. The gas flow range of the general inert gas back inflation protection is 0.5 ~ 42L/min.
The protection air flow is weak, the protection effect is not good, and the defects such as pores and welds are oxidized easily; If the gas flow is too large, it is easy to produce turbulence, the protection effect is not good, and the stable combustion of the arc will be affected.
When filling the pipe fitting, an appropriate gas outlet should be left to prevent excessive gas pressure in the pipe during welding. 25 to 50 mm before the end of the root pass welding, it is necessary to ensure that the gas pressure in the tube cannot be too large, in order to prevent the welding pool from blowing out or the root concave. When argon is used to protect the back of pipe welding, it is best to enter from the lower part, so that the air is discharged upward, and the gas outlet is away from the weld.