How to solve the defects occurred in argon arc welding?

Argon arc welding is a welding technology that uses argon as a shielding gas.

It has the characteristics of high current density, concentrated heat, high deposition rate, fast welding speed, and easy arc initiation, etc. 

In welding operations, defects are often caused due to various reasons. The following will teach you how to solve these defects in argon arc welding:

1. Porosity

The cavities formed by bubbles in the molten pool fail to escape during welding solidification.

(1) Causes

  Hydrogen, chlorine, air and other gas pollution

(2) Precautions

a. Using 99.99% pure argon gas;

b. Sufficient advance air supply and late air supply time;

c. Cleaning before welding;

d. Correctly selecting the protective air flow, clear the size and electrode extension length, etc.

2. Tungsten Inclusion

Excessive current causes the tungsten electrode to melt and evaporate, or tungsten electrode in contact with iron during operation, resulting in particles into the molten pool caused contamination.

(1) Causes

Contact arc or tungsten electrode melting.

(2) Precautions

a. Use high-frequency oscillator or high-voltage pulse generator to start the arc;

b. Reduce current or increase tungsten electrode diameter, tighten tungsten electrode chuck and reduce tungsten electrode extension length;

c. Replace cracked or torn tungsten electrodes.

3. Incomplete Penetration

The phenomenon of welding where the root of the joint is not completely fused is called incomplete penetration.

(1) Causes

a. The bevel edge of the weld joint is too blunt, the bevel angle is too small, or there is misalignment;

b. Insufficient welding current and uneven wire feed;

c. Welding speed is too fast or too slow, improper positioning of the welding wire, and the welding arc does not reach the root of the weld joint..

(2) Precautions

a. Leave a gap of 0.5-2mm for 3-10mm weldments, and the single-sided groove should be greater than 90 degrees;

b. Thoroughly clean the weldment and welding wire surface before welding;

c. Trim the blunt edge according to the process requirements;

d. Select the welding current according to the process requirements;

e. Take measures to prevent arc deviation;

f. Maintain a suitable arc length in welding.

4. Unstable Arc

(1) Causes

a. Tungsten electrode contamination;

b. Joint groove is too narrow;

c. Tungsten electrode diameter is too large;

d. Arc length is too long;

e. Rust, paint or oil on the weldment.

(2) Precautions

a. Clean up before welding;

b. Remove contaminated areas;

c. Use the correct size of tungsten electrode and chuck;

d. Adjust the nozzle distance;

e. Re-grind the cone angle of the tungsten electrode.

5. Welding nodules

It occurs when excessive heat concentration in a specific area causes molten iron to fall and form a protrusion.

(1) Causes

a. Excessive current;

b. Excessive feeding of welding wire;

c. Slow oscillation, leading to excessive heat concentration.

(2) Precautions

a. Adjust to a lower current;

b. Feed the wire correctly and increase the oscillation speed of the argon arc appropriately.

6. Shrinkage

 During the welding arc termination, the molten pool metal rapidly contracts towards the surroundings, while the molten hole has not yet been filled with molten metal, resulting in a cavity.

(1) Causes

Excessive current, rapid arc termination, and excessive heat concentration.

(2) Precautions

Adjust to an appropriate current, terminate the arc towards the groove side, and use high frequency to strike a few more times.

7. Lack of fusion:
(1) Causes

Insufficient current, misalignment, or improper positioning of the continuation wire.

(2)Precautions

Increase the current to repair the weld joint and adjust the angle of the continuation wire.

8. Wire Sticking

(1) Causes

a. Improper operation, excessive wire feeding;

b. Excessive current;

c. Too large a gap in the groove.

(2) Precautions

 Adjust to an appropriate current and feed the wire evenly.

9. Burn-through

(1) Causes

Excessive current and overly concentrated heat during the welding process.

(2) Precautions

Reduce the current, operate correctly, and increase the oscillation rhythm.