First, the main reasons for blackening and rusting of hot-dip galvanized angle steel:
1. Storage environment issues: When placed in a humid environment, the galvanized layer reacts with moisture, oxygen, and carbon dioxide in the air, producing corrosive substances such as basic zinc carbonate, resulting in black spots and rust on the hot-dip galvanized angle steel. If hot-dip galvanized angle steel is covered with a tarpaulin and stored without proper ventilation, moisture accumulation will significantly accelerate corrosion and blackening.
2. Production process issues: Excessive impurities in the galvanizing solution or defects in the passivation process after galvanizing can also cause blackening of the galvanized layer.
Second, requirements for handling blackening and rusting of hot-dip galvanized angle steel:
Small areas of blackening: The galvanized layer of the hot-dip galvanized angle steel must be repaired before use. It can only be used after successful repair.
Large areas of blackening: The hot-dip galvanized angle steel is considered defective and should be replaced immediately. Use is not recommended.
Third, recommendations for repairing hot-dip galvanized angle steel:
We recommend using high-zinc-content special galvanizing paint, preferably cold-dip galvanizing paint with a zinc content of 96%. The corrosion resistance of hot-dip galvanized angle steel is close to that of hot-dip galvanized steel. During construction, first grind away the blackened areas of the hot-dip galvanized angle steel to clean it, and then directly brush on the paint. This will achieve a corrosion resistance effect similar to that of the original hot-dip galvanized steel.
Post time: May-13-2026