Question

In case of TIG welding of aluminium alloys, the amount of shielding gas used can be determined from the band of white deposit (aluminium oxide) alongside the weld bead. A hairline width white band indicates that the quantum of shielding gas used has been

1. More than required

2. Lesser than required

3. Adequate as required

Which of the above is correct?
1. 1
2. 2
3. 3
4. Cannot be determined due to insufficient information

Answer 1

Correct Answer - Option 3 : 3

Explanation:

• In the TIG welding of aluminium alloys, a band of the white deposit is formed alongside weld bead, the chemical analysis which revealed it as aluminium oxide and is believed to be caused by the emission of electrons from the surface of aluminium (negative cathode).
• Electrons detach the oxide from the surface as they fly off.
• When the deposit band is of hairline width, it indicates shielding is just adequate.
• If the band is wider, it means that the gas flow is too much and gas is being wasted.