The joint formed between two connected bodies at the time of welding is called a weld. Both sides of the weld are subjected to welding heat during welding, and changes in structure and properties occur. This area is called the heat-affected zone. Due to the difference in welding materials, welding currents, etc. of the workpiece materials during welding, the welded joints and heat-affected zones may be overheated, embrittled, hardened, or softened after welding, and the performance of the weldment may also be degraded, which may deteriorate the weldability. This requires adjustment of the welding conditions. Preheating before welding, heat preservation during welding, and heat treatment after welding can improve the welding quality of weldments.
