Low carbon steel welding process

　　Low carbon steel has a carbon content of ≤0.25%, and its plasticity is good. Generally, it has no tendency to harden, is not sensitive to the welding process, and has good weldability. When welding such steels, special process measures are not required, and heat treatment (except electroslag welding) is usually not required after welding.

　　For low-carbon steel structures with a thickness greater than 50 mm, high-current multi-layer welding is commonly used, and internal stress annealing is eliminated after welding. When the structure with high welding rigidity in a low temperature environment is large, the temperature difference between the parts of the weldment is large, and the deformation is limited. The welding process is prone to generate large internal stress, which may cause cracking of the structure. Therefore, preheating before welding should be performed.

　　Low carbon steel can be welded by various welding methods, and the most widely used are electrode arc welding, submerged arc welding, electroslag welding, gas shielded welding and electric resistance welding.

　　When welding structural steel by fusion welding, the selection of welding materials and processes should mainly ensure the strength of welded joints and workpiece materials. Welding rod arc welding is generally low carbon steel structure, E4313 (J421), E4303 (J422), E4320 (J424) welding rod can be selected. When welding dynamic load structures and complex structures, E4316 (J426), E4315 (J427) or E5015 (J507) electrodes should be used. For submerged arc welding, H08A or H08MnA welding wire with flux 431 is generally used for welding.