In the field of metal joining, understanding different welding processes and their components is crucial. One key component in many arc welding processes is the electrode, which can be either consumable or non-consumable. The question asks to identify the welding process that uses a non-consumable electrode.

Welding Electrodes Explained

A welding electrode is a conductor that carries current to the welding arc. Depending on the welding process, electrodes are categorized into two main types:

• Consumable Electrodes: These electrodes melt during the welding process and become part of the weld metal. They are consumed as the weld progresses, requiring continuous feeding.
• Non-Consumable Electrodes: These electrodes resist melting and maintain their shape during the welding process. They primarily serve to establish and maintain the arc, with filler metal (if needed) added separately.

Gas Tungsten Arc Welding (GTAW) Explanation

Gas Tungsten Arc Welding (GTAW), often known by its older name Tungsten Inert Gas (TIG) welding, is the welding process that uses a non-consumable electrode. Here's why:

• Electrode Type: GTAW employs a tungsten electrode, which has a very high melting point (approx. $\text{3422}^\circ\text{C}$). This high melting point allows the tungsten electrode to withstand the intense heat of the arc without melting, thus making it non-consumable.
• Filler Material: In most GTAW applications, a separate filler rod is manually or automatically fed into the weld puddle. This means the electrode's primary function is to create the arc, not to provide filler material.
• Shielding Gas: An inert shielding gas (like Argon or Helium) protects the weld pool, electrode, and arc from atmospheric contamination, ensuring a high-quality weld.

GTAW is known for producing very clean, precise welds with excellent control, making it suitable for thin materials and critical applications.

Gas Metal Arc Welding (GMAW) Overview

Gas Metal Arc Welding (GMAW), commonly known as MIG (Metal Inert Gas) welding, utilizes a consumable electrode. In GMAW:

• Electrode Type: A continuously fed wire electrode, which is made of a material similar to the base metal, melts into the weld puddle. This wire serves as both the electrode and the filler material.
• Shielding Gas: An external shielding gas (usually a mixture of Argon and $\text{CO}_2$) protects the arc and weld puddle.

GMAW is widely used for its speed and efficiency in joining various metals.

Submerged Arc Welding (SAW) Details

Submerged Arc Welding (SAW) is another welding process that uses a consumable electrode. Key features include:

• Electrode Type: A continuously fed bare wire electrode is used. This electrode melts and becomes part of the weld.
• Flux Shielding: The arc and weld pool are 'submerged' under a blanket of granular flux. This flux melts to form a protective slag and adds alloying elements to the weld.

SAW is known for its high deposition rates and deep penetration, often used in heavy fabrication.

Flux Coated Arc Welding (FCAW) Basics

Flux Coated Arc Welding typically refers to Shielded Metal Arc Welding (SMAW), also known as "stick welding," where the electrode is coated with flux. Alternatively, it can refer to Flux-Cored Arc Welding (FCAW), which uses a tubular wire filled with flux. Both are consumable electrode processes:

• SMAW (Stick Welding): Uses a flux-coated stick electrode that is consumed during welding. The flux coating creates a shielding gas and slag.
• FCAW (Flux-Cored Arc Welding): Uses a tubular wire electrode filled with flux. This wire is continuously fed and consumed, with the flux generating shielding gas and slag.

These processes are versatile and widely used in construction and fabrication.

Welding Process Electrode Comparison

To summarize the types of electrodes used in these welding processes:

Based on the analysis, Gas Tungsten Arc Welding is the distinct welding process among the options that employs a non-consumable electrode.