Welding procedures-fillet welds

【Summary Description】 Fillet weld as steel structure welding process in the most common form of weld splicing, so many welders will encounter different styles of fillet welds, but also have different standards, so how can a good fillet weld, and get to meet the requirements of the fillet weld: 1 Selection of base material Below we take the base material as Q345, the size of 200x 125x 12mm test plate as an example for a brief introduction. 2 Selection of welding materials Welding material: select E5015(J507) electrode, the drying temperature is 350~400 ℃, heat preservation for 2 hours, the welding wire adopts the national standard ER50-6 (American standard ER70S-6). 3 Cleaning before welding For fillet welds, clean within 15~20mm on both sides of the weld. The oxide film, rust, oil and water on the surface of the plate are removed by grinding with grinding wheel or chemical treatment. 4 Assembly point fixing Generally, fillet welds require the weld gap to be as small as possible. Point solid is generally carried out on the back of the plate, and the point solid length is about 10mm. General point solid two to three points can be: 5 Welding parameters 6 Welding operation Base welding 1.1 the angle of welding rod and the method of driving rod The angle of the welding rod for root fillet welding is shown in the figure: use the right welding method, start the arc on the left side of the test plate, and weld the short arc. Weld to the right in a straight line, align the arc with the apex angle of the root, lower the arc, and ensure the fusion of the apex angle and the plates on both sides. When backing welding, the swing method adopts straight line transportation and fast welding without swing, so that the required penetration can be achieved. At the initial welding end and the final welding end of the weld, the phenomenon of magnetic bias blowing is easy to occur, which affects the quality of the weld. At this time, the angle of the welding rod should be adjusted appropriately, and the arc should be directed to the molten pool to control the magnetic bias blowing. Figure. 1.2 weld bead joint The joint shall start the arc 10mm in front of the crater. When the elongated arc moves to the crater quickly, the crater shall be filled along the crater shape and then welded normally. cover welding Before welding the cover surface, remove the root pass weld slag and spatter to prevent slag inclusion defects. The cover is welded in two passes, first welding the lower pass, and then welding the upper pass. When welding the lower weld bead, the arc should be aligned with the lower edge of the root weld bead, and the rod should be moved in a straight line, and the angle of the welding rod should be greater than 45; When welding the upper weld bead, the arc should be aligned with the edge of the root weld bead, and the straight wire can also swing horizontally, and the angle of the welding rod should be less than 45. Theoretical weld throat: the vertical distance from the root of the joint to the hypotenuse in the largest inscribed right triangle drawn in the fillet weld profile. Effective weld throat: the minimum distance from the fillet weld surface to the weld root, minus the raised portion. Actual weld throat: shortest distance between fillet weld surface and weld root. For concave fillet welds, the effective weld throat is equal to the actual weld throat because there is no convex part. Leg size: the distance from the root of the joint to the fillet weld toe. Weld toe: The intersection of the weld surface and the base metal. When determining the size of the fillet weld, it must be clear whether the fillet weld is convex or concave. Convexity refers to the slight convex on the surface of the weld, which is related to the height of the convex. The raised height of a fillet weld is the same as the reinforced height of a groove weld. If a weld is dimpled, it indicates that the weld surface is dimpled. For these two shapes, the weld size of the fillet weld with the same weld leg height is expressed as "the straight edge of the largest isosceles right triangle obtained in the fillet weld profile (the two weld legs are the same length)." Therefore, for a convex fillet weld, the weld leg is equal to the weld size, but for a concave fillet weld the weld size is slightly smaller than its leg length.

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