What are Welded Joints?
A welded joint is a material joining process formed by the fusion of two similar or dissimilar, with or without the application of pressure and filler metal. Based on the method of joint preparation, welding can be classified into two types:
- Fusion welding – in this welding process, where welding joint is obtained from the melting of the parent metal
- Non-fusion welding – In this welding process joint is produced without melting the parent metal
Types of Welded Joints
As per the requirement, assembly, design, and operating condition it is very important to make a proper weld joint. So based on the above parameter it requires different types of welded joints. As per the shape of the weld component, the thickness of the weld component plate, and the direction of applied force We can classify welded joint are as follow:
- Lap joint
- Butt joint
- Corner joint.
- Edge joint.
- T- joint.
When the joint is made by overlapping two parts, it is known as a lap joint. It is also known as a fillet joint. Based on the direction of the applied force There are three different types of fillet weld:
- Single transverse fillet joint.
- Double transverse fillet joint.
- Parallel fillet joint
Transverse fillet weld
It is the type of fillet weld where the direction of applied force is perpendicular to the weld. in transverse loading, one plate exerts a shear load and the other a tensile (or compressive) load on the weld. Mostly double transverse fillet weld is preferable, as in this case there is not any edge free to deflect.
Parallel fillet weld
In this type of fillet weld, the direction of applied force is parallel to the weld. For parallel loading, both plates exert a shear load on the weld. in this case, weld beads are on both sides of the plate. The asymmetric weld joint is prepared in case of an unsymmetrical section, in certain applications such as angle or “T”.
When the joint is when the two components lay approximately the same plan, it is known as the butt joint. In this welding, if the thickness of the plate is less than 5 mm then it is required beveling.
In case of plate thickness, 5 mm to 12.5 mm beveling needs to be provided on one side or both sides of the plate. Based on this butt joint can be further classified as:
- Square butt joint.
- Single V-butt joint.
- Double V-butt joint.
- Single U-butt joint.
- Double U-butt joint.
When the corner of both components is joint at the perpendicular to each other, then this joint is known as the corner joint.
In a tee joint, when one of the components is perpendicular to the other, and form a “T” like structure, known as a tee joint.
When the edges of both the components are parallel to each other with at least one of their edges in common, the joint is made at the common edges known as an edge joint.
Stress in Welded Joints
Depending on the type of welded joint and loading condition, tensile, compressive and shear stress are developed in the welded joint. It is very difficult to determine the stresses in the welded joint, as there is a variable and unpredictable parameter that comes into consideration.
- Homogeneities of the weld metal,
- Thermal stresses in the welds,
- Changes in physical properties due to high rate of cooling etc.
While calculating the stresses in the weld joint, we have to consider the following assumptions
- The load is uniformly distributed over the entire length of the weld.
- The stress is spread uniformly over its effective section.
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