Preheating and post-weld heat treatment: Purpose - crack prevention, also has the necessary effect of improving organization and function.

Preheating: During multi-layer welding, the temperature between layers shall not be lower than the preheating temperature, but the adverse effects of excessive temperature between layers shall be prevented to prevent post-weld heat treatment: In addition to the severe overheating of the joint area in electroslag welding, it is necessary to advance. Normally, other hot-rolled and normalized steel welds do not require heat treatment after welding.