For the grads of thermo-mechanical action at the thickness direction is very large, it is difficult to achieve good welds as welding thick plate.

• 厚板焊接时, 沿板厚方向的热机作用梯度过大, 造成焊缝金属难以获得优良焊接性能, 这是厚板焊接较困难的原因。