A galvanized layer with a rough surface is usually thicker than a smooth galvanized layer, so the corrosion resistance may be longer, but the appearance is not good, and generally this defect is acceptable. Therefore, it is not appropriate to reject as a quality reason.

The surface roughness of galvanized layer refers to the micro-geometric characteristics of the surface of galvanized layer with small spacing and micro-peak-valley irregularity. At present, the methods used are optical method, comparison method, needle tracing method and impression method.

The main reasons for the surface roughness defect of Angle steel galvanized layer are as follows:

1. The influence of "over-pickling" on the surface roughness of Angle steel galvanized layer in the process of plating pretreatment.

"Pickling" makes the surface of steel rough or bean marks, which is also one of the reasons for the rough surface of the workpiece after hot dip galvanizing.

Two, zinc solution temperature is too high or zinc soaking time is too long, the influence of Angle steel galvanized layer surface roughness.

When the temperature of zinc solution is too high, the time of zinc immersion is too long, or due to the influence of Angle steel composition and Sundlin effect, the zn-Fe alloy phase is generated too much or uneven, which will also cause surface roughness. The thicker the zinc layer, the more likely the surface to appear rough.

Surface roughness can also occur when the hot-dip galvanized Angle steel cools slowly after being removed from the zinc solution, or when the steel section is too thick, or when the hot-dip galvanized Angle steel immediately piles up without isolation.

Three, Angle steel manufacturing selection of steel composition or surface conditions, on the surface roughness of the Angle galvanized layer.

The surface of galvanized layer is relatively smooth and rough. Different from the "continuous hot dip galvanizing" of steel, steel pipe or steel wire, the hot dip galvanizing of steel Angle belongs to the category of batch hot dip galvanizing process, and the galvanized layer is not blown by the air knife. If the surface of the steel used for hot-dip galvanized Angle steel is originally rough, rusty pits or obvious rolling stripes, the surface will generally not be smoother than the original after hot-dip galvanized.

The composition of steel will also affect the formation of excessive or uneven Zn-Fe alloy phase layer due to sundlin effect, resulting in surface roughness.