With the rapid development of high-strength steel welding industry, it has been used by more enterprises, which shows that high-strength steel welding has a certain importance in the welding industry. So what are the general processes for high-strength steel welding? Let's discuss it together!

1. Scope of application

This process is applicable to the welding of marine high-strength steels that have been qualified for welding procedures. High-strength steels that have not been qualified for welding procedures are not within the scope of application of this general procedure.

2. Process content

1. Selection of welding materials and welding methods

(1) The welding method mainly adopts submerged arc automatic welding, CO2 gas maintenance welding and manual arc welding.

(2) Active welding wire H10Mn2G (brand BHM-5), flux HJ331, CO2 welding wire TWE-711 and welding rod TL-507 are selected as welding materials. The positioning welding adopts manual arc welding. The automatic welding wire needs to be kept warm at 100℃ before welding, and the technical electrode and flux need to be baked at 350℃~400℃ for 1~2 hours before being used for heat preservation. Once the above materials are wet, it is strictly prohibited to use.

2. Positioning welding and installation requirements

(1) Strong installation should be avoided during tack welding installation. The amount of butt misalignment should not exceed 1mm. The length of tack weld should be 50mm. The thickness of the throat of fillet weld should be less than the thickness of the formal weld. It is forbidden to strike arcs at non-welded places. Before formal welding, the 10mm on both sides of the weld bead and the inside of the groove should be polished and clean, and there should be no oil, water, burrs, rust and other debris. If there are cracks in the positioning weld, it should be completely removed before the formal welding.

(2) The welding seam of the installation horse plate, the lifting horse plate and the reinforcement row should be separated from the margin of the formal welding seam by not less than 30mm. When removing, it is not allowed to be removed by hammering, but only by gas cutting and then flattened with a carbon planer without damaging the surface of the base material, and then smoothed with a grinding wheel.

(3) Since the marine steel plates used are all high-strength steels, all welding, whether formal welding or tack welding, including repair welding, should be preheated before welding, and the preheating temperature is 120 °C.

3. Welding requirements and construction process

(1) The long straight welding seam of high strength steel should be submerged arc active welding, and multi-layer multi-pass welding should be used. The front seam is welded with 3 layers of 7~8 passes, and the reverse seam is welded with 2 layers and 5 passes. After the front welding seam is welded, the carbon planing of the reverse welding seam is used to clear the root, use an 8mm carbon rod to buckle the groove of 8mm (the whitening stops), and then use automatic welding. In order to reduce the welding deformation, put a 5mm anti-deformation when welding the front welding seam, and fix it with a horse plate when welding the reverse welding seam. It is necessary to control the welding line energy during welding, and keep the interlayer temperature at about 120 °C.

(2) After each welding seam, we need to clean up the welding slag, and check whether there are any defects such as pores and cracks in the welding seam. a weld.

(3) For the butt joints of other positions of high-strength steel, technical arc welding and CO2 gas maintenance welding are used. The technical electrode is TL-507, and the welding wire is TWE-711 and Supercored81-K2. Supercored81-K2 wire is only used for butt welding of high-strength steels thicker than 60mm. For the butt joints between steel plates of 25mm and below, use CO2 backing welding with V-shaped grooves; for butt joints between steel plates larger than 25mm, use CO2 welding with double-sided asymmetrical X-shaped grooves. In order to avoid welding deformation caused by welding shrinkage, it is necessary to add rows before welding. The standard of reinforcing rows is -20×200×300, and the distance is 150mm. After welding one side of the seam, move the row to the other side.

(4) Key points of manual welding and CO2 welding

① When welding, it is necessary to use multi-layer multi-pass welding, use small current, appropriate and fast welding speed, and small welding line energy. Short arc and small swing welding methods should be used as much as possible. Except for the bottoming bead, the thickness of other welding layers should be controlled within 2~4mm.

② In order to avoid the cracking of the backing bead, the welding current should be appropriately increased and the welding speed should be slowed down when welding the backing bead to increase the weld cross-section of the bead.

③ When welding the sectional slipway, weld the butt seam first, and then weld the fillet weld. When welding the butt seam, first weld the flat butt, and then weld the vertical butt; when welding the fillet weld, first weld the vertical fillet weld, and then weld the flat fillet weld.

④ For long straight welds, use the segmented de-welding method or the segmented and segmented method.

4. Repair and repair welding of weld defects

(1) The defects of the welding seam exceeding the standard can be eliminated by carbon arc gouging or grinding wheel, and arc or flame smelting is not allowed. After the defects are eliminated, a non-destructive inspection should be carried out to determine whether the defects are completely eliminated. Repair welding can be carried out after it is determined that the cleaning is eliminated.

(2) The groove after eliminating the defects is required to be ground into a U shape with a grinding wheel. The groove bottom is semi-circular, the groove length shall not be less than 100mm, and its depth shall transition to the two ends according to the slope of 4:1. There are burrs, pits and oxide layers.

(3) The welding materials and process requirements used for repair welding are the same as the formal welding seam. The repair welding of the same part shall not exceed two times.