Question

Two non-consumable tungsten electrodes are used in process.

• A. Atomic hydrogen welding
• B. Plasma arc welding
• C. Submerged arc welding
• D. Tungsten inert gas welding

Hint:

Remember: Atomic Hydrogen Welding uses A pair of electrodes. This is a unique setup compared to almost all other common arc welding methods which use a single electrode.

Answer 1

The Correct Option is A

1. The Mechanism of AHW:

• Electrode Configuration: Two tungsten electrodes are slanted toward each other. An AC arc is struck and maintained in the gap between their tips.

• Hydrogen Interaction: A stream of hydrogen gas is passed through the arc. The intense heat of the arc (exceeding 6000 K) causes the molecular hydrogen ($H_2$) to dissociate into atomic hydrogen ($H$).

• Exothermic Recombination: As the atomic hydrogen leaves the arc and touches the relatively cooler workpiece, it recombines back into molecular hydrogen. This recombination is a highly exothermic reaction, releasing a massive amount of heat concentrated on the weld area.

2. Comparing Other Processes:

• TIG (Tungsten Inert Gas) Welding: Uses only

one non-consumable tungsten electrode. The arc is formed between that single electrode and the base metal.

• Plasma Arc Welding: Similar to TIG, it primarily uses a single tungsten electrode located within a torch nozzle to create a constricted arc.

• Submerged Arc Welding: Typically uses a

consumable wire electrode that is buried under a layer of granular flux.