What is the type of welding defect caused due to poor deposition of weld rod is called?

Under fill is a type of welding defect that occurs when there is poor deposition of weld metal.

Cause: It happens due to insufficient filler material being deposited in the weld joint, often because of improper technique or incorrect welding parameters.

Appearance: The weld surface appears below the level of the adjacent base metal, leaving the joint weaker than required.

Other defects:
Porosity refers to gas pockets or voids trapped in the weld.

Undercut occurs when excessive melting leaves a groove along the weld toe.

Cracks are linear ruptures caused by stresses during solidification or cooling.

Conclusion: The defect due to poor weld metal deposition is called under fill.