Argon arc welding is an arc welding method in which the inert gas "argon" is used as a protective gas. The inert gas is ejected from the nozzle to form an inert gas protective layer in the welding area, which isolates the invasion of air and thus protects the arc and molten pool.This welding method has many advantages: good protection effect, high welding quality, no spatter, beautiful weld forming;Small welding deformation, realizing single side welding double side forming, ensuring the root welding penetration, carrying out various positions of welding;Can be used for welding various metals and alloys;Arc combustion stability, open-arc operation, no slag, easy to achieve automation.
Therefore, it is widely used in practical production.However, due to its weak wind resistance, TIG is especially sensitive to rust, water and oil stains, and has strict requirements on gas purity, groove cleaning and welding process, which is prone to produce welding porosity.
Influence factors of welding porosity:
1:Argon is not pure
The purity of argon is not less than 99.7% for carbon steel, 99.9% for aluminum, and 99.99% for titanium and titanium alloys.
2.Argon flow rates
Argon gas flow rate is too small, and its resistance to wind interference is weak.The near-wall laminar flow formed when passing through the nozzle is very thin. After the gas is ejected, it is easy to involve the air, and the protective effect of the molten pool becomes worse.Therefore, the flow rate of argon must be appropriate to stabilize the gas flow.
3.Argon leakage
4.effect of wind
The strong wind will cause the argon layer to become turbulent, resulting in poor protection.Therefore, when the wind speed is > 2m/s, windbreak measures should be taken;When welding pipe, the pipe mouth should be blocked to avoid the formation of ventilation in the pipe.
5.Influence of nozzle of welding gun
If the nozzle diameter is too small, when the effective protection range of argon gas around the arc is smaller than the molten pool area, poor protection will result in pores.Especially in field work, large diameter nozzle should be used when welding large tube to protect arc and weld pool effectively.
6.Distance between nozzle and workpiece
The distance is small and the sensitivity to crosswind is small.The distance is large and the ability to resist wind interference is weak.
7.The pressure in the cylinder is too low
Stop when the pressure in the cylinder is less than 1MPa.
8.Welding torch Angle is too large