What type of weld is characterized by a triangular cross-section?

A fillet weld is indeed characterized by a triangular cross-section. This shape results from the weld being applied at the joint between two surfaces, typically at right angles to each other. The triangular profile is formed where the weld bead rises above the base material, essentially filling the corner of the joint.

Fillet welds are commonly used in various welding applications as they provide good strength and are able to accommodate angular joints effectively. The design allows for reinforcement along both surfaces being joined, making them versatile for structural applications.

In contrast, butt welds have a more uniform cross-section that typically matches the base material instead of forming an obvious triangular shape. Groove welds are also designed to fill in a cut or groove in two pieces of material but do not typically have a triangular profile; their cross-section can vary based on the groove configuration. Plug welds are used to join two overlapping pieces by welding through a hole in the top piece, and their shape is not triangular in cross-section.

Understanding these distinct features helps in identifying the correct type of weld based on its geometric characteristics, as well as the intended applications in various structural scenarios.