1. Introduction to the

Submerged arc surfacing welding refers to a surfacing welding method in which the arc between the surfacing material and the parent material connected to the positive and negative electrodes of the welding power source is buried under the pre-laid granular flux in front of the arc.

Submerged arc surfacing flux function: protect the eyes, protect the pool, protect the weld bead, infiltrate the alloy, reduce splash, reduce the arc heat loss caused by heat radiation, protect the welding nozzle and so on.

Do not use flux protection during open-arc surfacing. Install a hood around the welding nozzle to shield arc light and protect operator's eyes. It does not use shielding gas in welding, so it is different from FGD in this respect.

Application: submerged arc surfacing welding because of the need for flux, it can only be used in the welding machine head before the maintenance of flux, such as plane surfacing, large curvature surface surfacing. And only suitable for flat welding or small slope surfacing. Open arc surfacing welding can be applied to almost any occasion (due to the large pool, cut no retaining device, can not be applied to the overhead welding).

2. The work environment

Open arc surfacing welding has arc light, and the smoke is larger than that of buried arc surfacing welding. Submerged arc surfacing arc is covered in flux, arc light is not exposed.

3. cooling

Common cooling methods include air cooling and water cooling. The cooling mode of open arc surfacing welding is easy to adjust, but that of submerged arc surfacing welding is not.

It is not suitable for submerged arc surfacing because it is easy to blow up fine powder when it is cooled by air. When water is cooled, due to the use of flux, water can not be cooled on the front of the weld just after welding, but only through the back of the base material. Moreover, the cooling effect is affected by the flow of cooling water on the one hand, and on the other hand, it is greatly affected by the thickness of the base material. The thicker the base material is, the worse the cooling effect will be.

Open-arc surfacing can be cooled by air or water. However, open-arc surfacing welding can not only pass water cooling through the back side of the workpiece like submerged arc surfacing welding, but also pass water cooling through the front side of the workpiece, and the cooling effect is adjustable (the cooling peak temperature can be changed by changing the position of cooling water relative to the molten pool, and the cooling speed can be changed by changing the velocity of cooling water). Since water is directly cooled on the front of the newly welded weld, the cooling effect is better. Therefore, eutectic microstructure is more likely to appear in the weld, and it is beneficial to improve the hardness of materials with a tendency to quench. In addition, due to the cooling of cooling water, the size of the weld and the whole welding area becomes smaller and the temperature increases less, which facilitates the subsequent weld bead to surfacing at a lower temperature and further improves the cooling effect.

In addition, the influence of welding heat on the base material during open-arc surfacing welding is small, which is very beneficial to the base material with poor weldability.