How to distinguish hot galvanizing from cold galvanizing?
The first difference between processes is:
Hot dip galvanizing is to remove oil, pickling, soaking, drying and then immerse the workpiece in the molten zinc solution for a certain period of time.
Cold galvanizing, also known as electro galvanizing, is to use the electrolytic equipment to put the workpiece into the zinc salt solution after oil removal and acid pickling, and connect the negative pole of the electrolytic equipment; place the zinc plate on the opposite side of the workpiece to connect the positive pole of the electrolytic equipment, connect the power supply, and use the current to move from the positive pole to the negative pole in the direction, and a layer of zinc will be deposited on the workpiece.
Appearance difference: the galvanized surface is relatively smooth and bright, and the plating layer with color passivation process is mainly yellow and green, showing seven colors. The plating layer with white passivation process is blue white or green, and the plating layer with white passivation process is slightly colorful with sunlight at a certain angle. It is easy to produce "electric burn" at the corner of the complex workpiece, which makes the zinc layer thick. It is easy to form a dead angle of current at the internal corner, which leads to the undercurrent gray area, where the zinc layer is thin. There is no zinc lump and caking on the whole workpiece. The appearance of hot-dip galvanizing is slightly rougher than that of electro galvanizing, which is silvery white. The appearance is easy to produce process water lines and a few droppings, especially at one end of the workpiece. However, the zinc layer of hot-dip galvanizing is dozens of times thicker than that of electro galvanizing, and its corrosion resistance is dozens of times that of electro galvanizing.
Difference of galvanized products:
1. The inner and outer walls of hot-dip galvanized steel pipes are galvanized, while the outer walls of cold galvanized steel pipes are only galvanized;
2. The cold coating is uniform and the thickness is very thin; the hot coating is thick and the thickness is uneven.
3. The appearance of cold plating is bright, and the color of hot plating is dark.
4. The corrosion resistance of cold coating is poor because it is thinner; the corrosion resistance of hot coating is good because it is dozens of times thicker than that of cold galvanizing, and it forms a penetrating layer with the base metal.
5. The surface of the cold galvanized steel pipe looks bright, smooth and flat; the surface of the hot galvanized steel pipe is not as smooth as that of the cold galvanized steel pipe, and the surface of the hot galvanized steel pipe seems to have some uneven bumps, and the surface is not bright, not too reflective.
The above is about how to distinguish between hot galvanizing and cold galvanizing. It is provided by Jinan Galvanized Pipe Co., Ltd. for more information, please consult http://www.jnlhjscl.com Website.