Phenomenon: the height of the weld is too large or too small; Or the width of the weld is too wide or too narrow, the transition part between the weld and the base metal is not smooth, the surface is rough, the longitudinal and transverse of the weld are not neat, and the concave amount of the weld at the fillet weld is too large.

Cause: poor straightness of weld groove processing, improper groove angle or unequal assembly clearance. Excessive current during welding will make the welding rod melt too fast, it is difficult to control the weld formation, and too small current will make the welding rod produce "bonding phenomenon" during welding arc striking, resulting in incomplete welding or weld beading. The welder is not proficient enough, the method of strip transportation is improper, such as too fast or too slow, and the electrode angle is incorrect. Improper selection of welding process parameters in submerged arc automatic welding process.

Prevention measures: weld groove shall be processed according to the design requirements and welding specifications, and mechanical processing shall be used as far as possible to make the groove angle, straightness of groove edge and straightness of groove edge meet the requirements, and manual gas cutting and manual shovel cutting shall be avoided. During assembly, the weld gap shall be uniform to lay a foundation for ensuring welding quality. Select appropriate welding process parameters through welding process qualification. Welders shall work with certificates, and the trained welders shall have certain theoretical basis and operation skills. The last layer of Multi-layer Weld on the welding surface is the weld. Under the condition of ensuring the fusion with the bottom layer, the welding current smaller than that between layers shall be adopted, and the（ φ 2.0mm~3.0mm). The strip conveying speed shall be uniform, advancing longitudinally rhythmically, and swinging laterally with a certain width to make the weld surface neat and beautiful.