The importance of preheating before welding of steel structures

Importance of preheating before welding of steel structure

As we all know, steel structure is a kind of building structure, which has relatively high strength and high resistance to deformation. Very good, of course, it is not enough to have its own conditions, which also requires reasonable operation to make it play better. In fact, the structure needs to be preheated before welding, so what role can the preheating process play?

1) Preheating can slow down the cooling rate after welding, which is conducive to the escape of diffusible hydrogen in the weld metal and avoids hydrogen-induced cracks. At the same time, the degree of hardening of the weld and the heat-affected zone is reduced, and the crack resistance of the welded joint is improved.

2) Preheating can reduce the welding stress of steel structures. Uniform local preheating or overall preheating can reduce the temperature difference (also known as temperature gradient) between the workpieces to be welded in the welding area. In this way, on the one hand, the welding stress is reduced, and on the other hand, the welding strain rate is reduced, which is beneficial to avoid welding cracks.

3) Preheating can reduce the restraint of welded steel structures, especially for fillet joints. With the increase of preheating temperature, the incidence of cracks decreases .

Through the introduction, we learned that it is very important to carry out the preheating process before the welding of the steel structure, it can ensure the quality of the structure during welding, improve the crack resistance of the welded joint, Avoid cracks. Therefore, we must carry out the corresponding preheating process of the structure before welding, so as to ensure the quality and efficiency of the construction.