Question

Which of the following is an example of a Solid-State Welding process?

• A. Submerged Arc Welding (SAW)
• B. Gas Metal Arc Welding (GMAW)
• C. Electron Beam Welding (EBW)
• D. Friction Stir Welding (FSW)

Hint:

Solid-State Welding Processes include:
- Friction Stir Welding (FSW).
- Diffusion Welding (DFW).
- Explosive Welding (EXW).
- Ultrasonic Welding (USW).
These processes avoid common fusion defects because they never cross the liquidus temperature.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
This question asks to identify which of the listed welding processes operates entirely in the solid state, without causing macroscopic melting of the base metals.

Step 2: Key Formula or Approach:
Welding processes are broadly classified into:
1.

Fusion Welding: Joints are formed by melting and coalescing base metals with or without filler metal (e.g., arc, gas, and high-energy beam processes).
2.

Solid-State Welding: Joining is accomplished through pressure, friction, or diffusion at temperatures below the melting point of the base metals.

Step 3: Detailed Explanation:

• Friction Stir Welding (FSW):
- A non-consumable rotating tool with a profiled pin is plunged into the joint line between two sheets.
- The rotation and translation of the tool generate intense frictional heat, softening the metal into a highly plastic state.
- The tool mechanically stirs the plasticized material together, forming a solid-state joint under high pressure.
- At no point does the metal reach its melting temperature. This prevents defects like solidification cracking, gas porosity, and excessive distortion.

• Fusion Welding Processes (Incorrect Options):
- Submerged Arc Welding (SAW) and Gas Metal Arc Welding (GMAW) utilize an electric arc to melt the electrode and base metal.
- Electron Beam Welding (EBW) uses a focused, high-energy stream of electrons to melt and vaporize metal to form deep keyhole welds.


Step 4: Final Answer:
Friction Stir Welding (FSW) is a solid-state welding process.
Therefore, option (D) is the correct choice.