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Fusion welding and thermal cutting.
In welding, due to the different thickness, structure and use conditions of the weldments, the joint type and groove form are also different. The types of welded joints are: butt joints, T-joints, corner joints and lap joints.
01. a butt joint.
The joint with the surface of two pieces forming an angle greater than or equal to 135° and less than or equal to 180° is called a butt joint. Among the various welded structures, it is the most used joint type. The thickness of the steel plate is less than 6mm, and the groove is generally not opened except for important structures.
When the thickness difference (δ-1) between the two plates butted by the steel plate with different thicknesses does not exceed the provisions of Table 1, the basic form and size of the weld groove are selected according to the size data of the thicker plate. Otherwise, a single-sided or double-sided thinning should be made on the thick plate as shown in Figure 1, with a thinning length of l 3 (δ-1).
Fig.1 Butt of plates of different thicknesses (a) thinning on one side; (b) Thinning on both sides.
02.Corner joints.
The joint with an angle greater than 30° and less than 135° between the end faces of the two weldments is called an angular joint, see Figure 2. This joint is not well stressed and is often used in unimportant structures.
Fig. 2 corner joint (a) I-shaped groove; (b) Unilateral V-shaped groove with blunt edge.
03.T-joints.
The joint that forms a right angle or nearly a right angle between the end face of one piece and the surface of another piece is called a T-joint, see Figure 3.
Fig.3. T-joint.
04.Lap joints.
The joint formed by two partially overlapping pieces is called a lap joint, see Figure 4.
Fig.4. Lap joint (a) I-shaped groove;
b) Plug welding of round holes;
c) fillet welding in long holes.
According to its structural form and the requirements for strength, lap joints are divided into three forms: non-beveling, round hole inner plug welding and long hole inner fillet welding, see Figure 4.
The lap joint of the I-shaped groove is generally used for steel plates with a thickness of less than 12mm, and its overlapping part 2 (δ1+δ2) is welded on both sides. Such joints are used in uncritical structures.
When the area of the overlapping part is large, according to the plate thickness and strength requirements, different sizes and quantities of round hole inner plug welding or long hole inner fillet welding joint type can be used.