Submerged arc welding is mainly suitable for flat position welding. If certain tooling aids are used, corner welding and horizontal welding can be realized. The main factors affecting the shape and performance of submerged arc welding seam are welding process parameters and conditions. The welding process parameters affecting the shape and size of submerged arc welding seam include welding current, arc voltage, welding speed and wire diameter.

Hot crack, in the process of weld cooling, because the sulfur and phosphorus impurities in the steel or welding material form a variety of brittle and hard eutectic with low melting point, in the process of weld cooling, the solidified eutectic with low melting point is in a tensile state, which is easy to crack.

Reinforcement is not only the need of welding process, but also has an impact on the safe operation of the vessel, especially the fatigue life. The welding of pressure vessel is mostly multi pass welding (such as manual welding and automatic welding).

A large number of studies have proved that the hydrogen content of the welded joint, the hardening tendency of the steel and the restraint stress of the joint are the three major factors causing the welding delay crack, and the welding delay crack is caused by the joint action of these three factors.

Welding cracks are relatively dangerous welding defects, which seriously affect the performance and safety of welded structures. Many damage accidents of welded structures are caused by welding cracks.

Sometimes, the defects in the actual production of high frequency welded pipe are not caused by one reason, but usually the result of a variety of factors.

In order to ensure that the forming section, welding section and sizing section do not produce "pipe pulling" and "stacking", according to the rolling principle of high frequency straight seam welded pipe, it is necessary to ensure that the welding tube blank maintains proper tension in each section.

Welding is a process in which two separated objects are combined with atoms (molecules) to form a whole by means of energy. This welding method can not only connect metal materials such as steel, aluminum, copper and titanium, but also connect non metals such as plastics and ceramics. It can also solve the connection between metals and non metals, such as manual arc welding, gas shielded arc welding, self shielded arc welding Submerged arc welding and other welding methods.

Welding heat affected zone (HAZ) is different from weld. The performance of weld can be guaranteed by adjusting and redistributing chemical composition and proper welding process. However, the performance of HAZ can not be adjusted by chemical composition.

In the welding process, molten metal particles and slag will fly around. The spatter in welding process is about short circuit splash, gas precipitation splash, free transition splash.