The welding of wire in construction generally includes: flash butt welding, resistance spot welding, arc welding, electro slag pressure welding, the submerged arc pressure welding of T joint of embedded parts, and the pressure welding of reinforcement.
1. Flash butt welding: 300 welding joints of the same grade and same diameter steel bars in the same working class shall be taken as one inspection batch completed by the same welder. If there are less than 300 joints in the same class, it is also used as a test batch. The mechanical property test includes tensile test and bending test. Six specimens should be cut from each batch of finished products, three of them for tensile test and the left for bending test. The length of the tensile specimens is generally greater than or equal to 500mm (500~650mm). The length of cold-bending specimens is generally greater than or equal to 250mm (250~350mm).
(1) the joint shall not have transverse lines;
(2) contact with the electrode surface of the steel, Ⅰ ~ Ⅲ grade steel welding cannot have obvious burns; When Ⅳ grade steel welding shall not be burned; Negative temperature flash butt welding, for steel Ⅱ ~ Ⅳ level, shall burn;
(3) the bending Angle at the joint shall not be greater than 4. ;
(4) the deviation of the reinforcement axis at the joint shall not be greater than 0.1 times the diameter of the reinforcement and at the same time shall not be greater than 2mm.
2. Resistance spot welding: welding products of the same grade, diameter and size of steel bars shall be of the same type, with each batch of 200 pieces.
3. Electric arc welding: under the field installation conditions, 300 joints of the same type (same with steel bar level, same with joint type and same with welding position) are used as one batch on each floor. If less than 300 joints, they are still used as one batch. Three joints were cut from each batch of finished products for tensile test, and the length of the specimen was generally more than 500 mm (500~650mm).
4. Electro slag pressure welding: in general structures, every 300 joints of the same type (the same level of steel bar and the same welding position) are used as one batch; In cast-in-situ concrete frame structure, 300 joints of the same type are used as a batch in each floor. 3 joints were cut from each batch of finished products for tensile test, and the length of the specimen was generally more than 500 mm (500~600mm).
(1) the joint welding bag shall be uniform and free from flow blisters and cracks. The width and thickness of the welding bag from the steel bar surface to its outer edge shall be 2mm or more, and the thickness shall be 4mm or more;
(2) during welding, the steel bar shall not have obvious burns on the surface, and its zero line shall not be connected to the main reinforcement of the component;
(3) the deviation of the reinforcement axis at the joint shall not be greater than 0.1 times the diameter of the reinforcement and at the same time shall not be greater than 2mm.
(4) the bending Angle at the joint shall not be greater than 4.
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