The type of weld represented by the shaded region in the figure is

The correct option is fillet.

Understanding Welded Joints and Types of Welds:
Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing fusion. Different joint designs require specific types of welds. The two most common types are groove welds and fillet welds.

1. Fillet Welds:
A fillet weld joins two surfaces that are approximately perpendicular or meet at an angle (usually 90 degrees). The cross-section of a fillet weld is roughly triangular. They are widely used for joining plates in configurations such as:
• T-joints: Where one plate is perpendicular to another, forming a "T" shape.
• Lap joints: Where two overlapping plates are joined at their edges.
• Corner joints: Where two plates meet at their edges to form an "L" shape.

Analysis of the Provided Images:
• Image 1 (first diagram): Shows a vertical plate placed perpendicularly on top of a horizontal plate, forming a T-joint. The shaded region at the corner junction has a distinct triangular cross-section, which represents a fillet weld.
• Image 2 (reference diagram): Provides several illustrative examples of fillet welds in different configurations. Specifically, it labels "Fillet weld on corner joint" (with a "weld point" indicator), "Fillet weld on lap joint", and "Fillet weld on T-joint". The configuration in Image 1 is a direct match to the single-sided version of the "Fillet weld on T-joint" shown in Image 2.

Why the Other Options are Incorrect:
• Groove: Groove welds are deposited in a prepared channel or groove between two joint members (such as butt joints where plates lie in the same plane).
• Plug: A plug weld is formed by filling a circular hole in one overlapping plate to join it to the member beneath it.
• Spot: A spot weld is a localized weld made at a small contact point, typically using resistance welding, without a continuous triangular bead along a joint corner.