There are many reasons for rusting after phosphating, depending on the situation,
First, the concentration of the phosphating agent in the phosphating bath is insufficient, resulting in a phosphating film that is too thin or loose and does not isolate the air well.
Second, the water washing after phosphating is insufficient, or the acidity of the washing tank is too high, causing acidic substances to remain on the workpiece, causing the acid solution to damage the phosphating film and causing rust.
Third, the stored environment is too humid or too acidic, and it is also prone to rust.
