The difference between phosphating line and blackening line: 1. Generally, the blackening neutral salt spray time is less than 20 hours, and the phosphating anti-corrosion performance is far better than blackening. 2. The blackening film is smooth, which can achieve a bright effect, while the phosphating film is relatively rough (only relatively), which is generally matte, but if there is oil on the phosphating surface, it can also have a bright effect. Both blackening line and Bluing line are oxidation treatment of iron and steel. The purpose is to obtain a dense oxide film of Fe3O4 on the surface of iron and steel for corrosion resistance. The color of blackening line is dark black, while the color of Bluing line is dark black The color is blue black; phosphating refers to the phosphate coating treatment on the surface of steel, which aims to obtain the phosphate compound with manganese, zinc, calcium, iron, etc., playing the role of corrosion resistance and antifriction. The color of phosphating film includes light gray, dark gray, black, etc The common point is that the chemical conversion film on the surface of steel has no effect on the internal structure and microstructure of steel. Small components generally refer to small steel parts, which must be degreased, pickled and Phosphated before painting.