What is a common defect that occurs due to improper arc length?

• A. Porosity
• B. Undercut
• C. Overheating
• D. Weld spatter

Answer: (B)

The correct choice highlights undercut as a common defect associated with improper arc length. When the arc length is too long, it can result in inadequate heat input to the base material, leading to insufficient melting of the edges of the weld. This insufficient melting creates a groove or depression, referred to as undercut, along the edges of the weld bead.

Undercut not only affects the aesthetic quality of the weld but also compromises the strength and integrity of the joint, as it reduces the effective cross-sectional area that carries loads. Proper arc length is crucial in achieving a sound weld, ensuring sufficient heat is delivered to melt both the base and filler materials evenly.

In contrast, porosity generally arises from issues related to moisture, contamination, or improper shielding gas, while overheating tends to cause burn-through or excessive distortion and is not directly caused by arc length alone. Weld spatter can occur from various issues, including improper settings or techniques, but it is not specifically linked to arc length as undercut is.