焊接接头是焊缝和热影响区的总称。
Welding joint is the floorboard of welding seam and heat affected zone.
电弧焊接时，焊接电弧使焊件局部加热和熔化，同时加入填充金属(焊条或焊丝)，形成金属熔池，并不断把热量传给周围冷的母材金属。
Arc welding, the welding arc make welding and local heating and melting, while adding a filler metal (welding rod or wire), the formation of metal molten pool, cold and constantly pass quantity of heat to the surrounding of the base metal.
当电弧移开后，熔池的温度迅速降低，熔池中液体金属凝固成焊缝。
After the arc removed, quickly reduce the temperature of the molten pool, liquid metal in the molten pool solidified into a weld.
由于热传导的作用，母材将受到不同程度的加热和冷却，相当于进行了一次热处理，使其组织和性能发生了变化，这部分金属所占的区域就称为焊缝的热影响区。
Due to the effect of heat conduction, the base will be subject to different degree of heating and cooling, equivalent to a heat treatment, the microstructure and property has changed, this part of the metal of the area is called the weld heat affected zone.