Final answer:
The types of defects seen in fusion welded joints are: Undercut, Overlap, and Incomplete Fusion.
Step-by-step explanation:
The types of defects seen in fusion welded joints are: Undercut, Overlap, and Incomplete Fusion. These defects occur during the welding process and can weaken the joint, affecting its mechanical properties.
Undercut is a groove melted into the base metal adjacent to the weld toe, which can reduce the cross-sectional area of the joint. Overlap happens when the weld metal extends beyond the toe of the weld, resulting in an uneven surface. Incomplete fusion occurs when the weld metal fails to fuse with the base metal, leading to a weak bond.