The analysis of welding crack control measures of thick plate steel structure can be mainly started from the aspects of material selection, welding process parameters, preheating and tempering treatment, cooling rate, etc.

Specifically includes the following points:

Select the right welding material: according to the nature of the welding material, strength requirements and the use of the environment and other factors, select the welding material with the right chemical composition and mechanical properties to ensure the quality and reliability of the welding joint.

Control the chemical composition of the weld: reduce the content of elements that are easy to segregate in the base metal and welding materials, such as sulfur and phosphorus, and reduce the content of carbon in the steel, which can reduce the tendency of hot cracking. At the same time, Mn content is increased to improve the thermal cracking resistance of the weld.

Control welding process parameters and conditions: reasonable control of welding current and welding speed, so that the width to depth ratio of the upper section of each weld pass reaches a suitable range, in order to improve the thermal cracking resistance. At the same time, the shape of welding pool is controlled to avoid the formation of sharp and long welding pool which is easy to crack.

Pre-welding and post-welding tempering: Pre-welding preheating can reduce the tendency to form cracks, preheating helps to slow down the cooling rate of the material and reduce welding residual stress. Post-welding tempering can also help eliminate residual stress and reduce the probability of crack formation.

Reasonable arrangement of welding sequence: Using a reasonable welding sequence, so that most welds are welded under less constraint, which can reduce the tensile stress of weld shrinkage, thereby reducing the tendency of hot cracking.

In addition, some special welding methods can also be used, such as gas shielded welding, which uses protective gases to form a local protective layer around the arc to prevent the intrusion of harmful gases and ensure the stability of the welding process.