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Welding Joints

Welding Joints Points : Welding Joints, Butt Joint, Corner Joint, Edge Joint, Lap Joint, Tee Joint Welds can be geometrically prepared in many different ways. The five basic types of weld joints are the butt joint, lap joint, corner joint, edge joint, and T-joint. Other variations exist as well-for example, double-V preparation joints are characterized by the two pieces of material each tapering to a single center point at one-half their height.
Single-U and double-U preparation joints are also fairly common instead of having straight edges like the single-V and double-V preparation joints, they arc curved, forming the shape of a U. Lap joints are also commonly more than two pieces thick—depending on the process used and the thickness of the material, many pieces can be welded together in a lap joint geometry.

Often, particular joint designs are used exclusively or almost exclusively by certain welding processes. For example, resistance spot welding, laser beam welding, and electron beam welding are most frequently performed on lap joints. However, sonic welding methods, like shielded metal arc welding, are extremely versatile and can weld virtually any type of joint. Additionally, some processes can be used to make multi pass welds, in which one weld is allowed to cool, and then another weld is performed on top of it. This allows for the welding of thick sections arranged in a single-V preparation joint, for example.

The cross-section of a welded butt joint, with the darkest gray representing the weld or fusion zone, the medium gray the heat-affected zone, and the lightest gray the base material.

After welding, a number of distinct regions can he identified in the weld area. The weld itself is called the fusion zone-more specifically, it is where the filler metal was laid during the welding process. The properties of the fusion zone depend primarily on the filler metal used, and its compatibility with the base materials. It is surrounded by the heat-affected zone, the area that had its microstructure and properties altered by the weld. These properties depend on the base material’s behavior when subjected to heat. The metal in this area is often weaker than both the base material and the fusion zone, and is also where residual stresses are found.
a) B, Butt Joint A joint between two members lying approximately in the same plane.
b) C, Corner Joint A joint between two members located approximately at right angles to each other in the form of an angle.
c) E, Edge Joint A joint between the edges of two or more parallel or mainly parallel members.
d) L, Lap Joint A joint between two overlapping members.
e) T, Tee Joint A joint between two members located approximately at right angles to each other in the form of a T.

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