In Submerged Arc Welding, _____________________ electrode is used in combination with a flux feeder tube.

Explanation:

Submerged Arc Welding (SAW)

Definition: Submerged Arc Welding (SAW) is a highly efficient welding process that involves the formation of an arc between a continuously-fed consumable electrode and the workpiece. The arc and molten weld pool are completely submerged under a blanket of granular fusible flux, which provides protection from atmospheric contamination.

Correct Option: The correct option in Submerged Arc Welding is option 4, which states that a "consumable bare" electrode is used in combination with a flux feeder tube.

Working Principle: In Submerged Arc Welding, the consumable electrode is continuously fed into the welding zone while the granular flux covers the arc and molten weld pool. The flux melts and forms a protective layer over the weld, preventing oxidation and contamination from the atmosphere. The electrode melts and deposits filler material into the weld joint, creating a strong, solid weld after cooling.

Advantages:

• High deposition rates due to the continuous feeding of the consumable electrode.
• Excellent quality welds with minimal contamination and defects, thanks to the protective flux layer.
• High efficiency and productivity, making it suitable for large-scale welding operations.
• Minimal spatter and smoke production, resulting in a cleaner work environment.

Disadvantages:

• Limited to horizontal or flat positions due to the use of granular flux.
• Requires equipment for handling and feeding the flux and electrode.
• Not suitable for thin materials or intricate welds due to the high heat input.

Applications: Submerged Arc Welding is widely used in industries that require high-quality, high-strength welds on thick materials, such as shipbuilding, pressure vessel fabrication, structural engineering, and pipeline construction.

Analysis of Other Options:

Option 1: Non-consumable baked carbon electrode

Non-consumable baked carbon electrodes are not used in Submerged Arc Welding. These electrodes are typically used in processes like carbon arc welding or gouging, where the electrode does not melt and deposit filler material into the weld. The primary function of carbon electrodes is to create an arc for cutting or gouging applications rather than welding.

Option 2: Non-consumable tungsten electrode

Non-consumable tungsten electrodes are primarily used in Tungsten Inert Gas (TIG) welding. In TIG welding, the tungsten electrode is used to create an arc that melts the base material, and filler material may be added separately. Tungsten electrodes do not melt and deposit filler material into the weld, making them unsuitable for Submerged Arc Welding, which relies on the continuous deposition of filler material from the consumable electrode.

Option 3: Non-consumable graphite electrode

Non-consumable graphite electrodes are generally used in electric arc furnaces for steelmaking and other high-temperature applications. These electrodes do not melt and deposit filler material, which is essential for Submerged Arc Welding. The primary function of graphite electrodes is to conduct electricity and create high-temperature conditions for melting metals, rather than welding.

Option 5: Consumable coated electrode

Consumable coated electrodes are used in Shielded Metal Arc Welding (SMAW), also known as stick welding. These electrodes have a flux coating that provides shielding and stabilizes the arc. However, they are not suitable for Submerged Arc Welding, which requires a continuous feed of a bare electrode in combination with a separate flux feeder tube. In SAW, the flux is granular and fed separately, while the electrode is bare and continuously fed into the weld zone.

In conclusion, the correct option for Submerged Arc Welding is option 4, which specifies the use of a consumable bare electrode in combination with a flux feeder tube. This configuration allows for high-efficiency welding with excellent quality and minimal contamination, making it suitable for large-scale industrial applications.