What is the role of crater fill in GMAW termination?

• A. It removes spatter from the weld.
• B. It increases arc length.
• C. It changes the shielding gas composition.
• D. It fills the end crater of the bead to prevent crater cracking and ensure a sound termination.

Answer: (D)

Crater fill is about finishing the weld with a solid end. When you stop the arc, the last portion of weld metal forms a small crater that cools and contracts, creating a place where cracks can start. By briefly laying metal into that crater as you finish, you smooth the transition to the base metal and reduce the tensile stresses that can cause a crack to propagate. This empty crater ends up being a weak point if left unfilled, so filling it helps ensure a sound termination of the bead. It doesn’t involve removing spatter, changing the arc length, or altering the shielding gas—the gas flow and arc length controls stay the same—so crater fill specifically serves to prevent crater cracking and produce a robust termination.