When electrode arc welding is used, E5015 (J507) and E5016 (J506) electrodes can be used for thin plates without grooves; E5515 (J557) and E5516 (J556) flux welding should be used for thick plates with grooves.
As a high-strength welded structural steel, Q390B steel plate has a low carbon content, usually the mass fraction of carbon is less than 0.18%, and the weldability requirements are also considered in the design of the alloy composition, so low carbon Quenched and tempered steel welding is basically similar to normalizing steel.
Thermal cracks in the weld and liquefaction cracks in the heat-affected zone. Low-carbon quenched and tempered steel generally has low carbon content and high manganese content, and the control of S and P is also strict, so the hot cracking tendency is small, but the low-alloy high-strength steel with high nickel and low manganese type will Increased tendency to generate thermal and liquefaction cracks.
The material should have high strength, sufficient deformation force and excellent processing performance in terms of requirements. The steel of the load-bearing structure must have tensile strength, elongation, yield point and the content of carbon, sulfur and phosphorus must be guaranteed to be qualified. At the same time, the welded structure must have the qualification guarantee of the cold bending test. It is required that the structure bearing the dynamic load and the important tensile or bending welded structure must have the impact toughness guarantee at room temperature or negative temperature. Past practical experience tells us that q235b, q345b, Q390B and Q420B all meet the requirements.
Various properties that steel can exhibit under load, such as: strength, plasticity, toughness and cold bendability. Performance indicators of steel strength performance mainly include: elastic modulus, yield strength, tensile strength, ratio limit and so on. Among them, the designer believes that the yield strength is the maximum stress that the steel can reach. When the stress exceeds the yield point, it will produce obvious plastic deformation without breaking immediately. This is the plasticity of the steel. So the yield strength is the best table.
