The welding process of cast iron is generally divided into hot welding, semi-hot welding, cold welding three kinds of technology, different welding process selection of welding materials are different.

 

The hot welding process of cast iron is to preheat the cast iron to 600 ~ 700 ℃ as a whole or partially, and keep the temperature in the welding process. After welding, it will cover asbestos powder or other thermal insulation materials in the red hot state, and slow cooling is conducive to graphite precipitation. The advantage of the hot welding method is to reduce the temperature difference between the weld and the base metal, so as to reduce the stress level of the welded joint, and to prevent the crack, white mouth and hardened tissue.

 

The semi-hot welding process of cast iron is to preheat the cast iron to 300 ~ 400 ℃ as a whole or partially, and maintain the temperature during the welding process. The semi-hot welding method improves the construction condition and reduces the welding cost, but the crack resistance of the weld deteriorates.

 

Generally, the cold welding process of cast iron is not preheated before welding. When the ambient temperature is low or the welding constraint is large, it can be preheated 100 ~ 150℃ before welding. Special welding materials and necessary technological measures are often used in cold welding of cast iron.