What Is a Key Joint?

Welded joints are the most basic component of welded structures, and the form of welded joints is a key factor affecting structural performance and safety. Common forms of welded joints are butt, fillet, T-joint, and overlap.

Welded joints are the most basic component of a welded structure, and are the key factors affecting the performance and safety of the structure. The joint form design should be comprehensively considered based on factors such as welding method, structural shape and size, strength requirements, amount of filler metal, and ease of bevel processing. Common forms of welded joints are butt, fillet, T-joint, and overlap.

Common joint forms and sizes in production are shown in Figure 1.

When the joint is a right-angle connection, an angle joint or a T-shaped joint should be used.

In order to ensure the penetration of the weld on the workpiece, when using arc welding to weld thicker materials, we should also consider opening a groove at the joint. There are four basic types of grooves commonly used in manual arc welding: I-shaped grooves, V-shaped grooves, U-shaped grooves and X-shaped grooves. When welding thick plates with T-shaped or corner joints, K-shaped can also be opened The bevel is shown in Figure 1 (b) (c).

The selection of the bevel form is mainly based on the plate thickness and penetration requirements, and the possibility of bevel processing and the weldability of the weld should be considered. For example, if the plate thickness is less than 6mm, an I-shaped groove is used, that is, no groove is opened. V-shaped and U-shaped grooves only need to be welded on one side, which has good weldability, but it is easy to produce angular deformation after welding. X-shaped and double-sided U-shaped grooves are welded on both sides, evenly heated and less deformed, but must be weldable on both sides. The U-shaped groove is wider than the V-shaped groove at the root and is easy to weld through. However, the shape of the groove needs to be obtained by cutting and the cost is high, so it is only used in important thick plate structures. The V-shaped groove can be processed by gas cutting or plasma cutting, which has a lower cost, but can also be processed by cutting, which is more common. ^[1]