The difference between hot-dip galvanized and cold-dip galvanized metal stamping materials

There is a big difference between hot-dip galvanizing and cold-dip galvanizing of metal stamping parts, which are specifically mentioned in the following aspects; the hot-dip galvanizing of metal stamping parts materials generally has a thicker zinc layer, about 10um or more, and has strong anti-corrosion ability. Therefore, it is a kind of galvanizing process that is usually used, and electro-galvanizing is very thin, about 3~5um. The hot-dipped surface of metal stamping parts is rough and bright. In severe cases, there are spangles, while electroplating is smooth and dark (stained). The galvanized steel sheet produced by the electroplating method has good processing performance, but the coating is thinner and the corrosion resistance is not as good as the hot-dip galvanized sheet. Cold galvanizing is electro-galvanizing. The amount of galvanizing is very small, and only the outer pipe wall is galvanized (hot-dip galvanized). Both inside and outside are plated), only 10-50g/m2, its corrosion resistance is much different than that of hot-dip galvanized pipe; the metal stamping parts material hot-dip galvanized sheet and cold-dip galvanized sheet have a big difference in the amount of galvanization, The galvanizing amount of hot-dip galvanizing can not be too small, generally the minimum is 50~60g/m2 on both sides, and the maximum can be 600g/m2. And the galvanized layer of cold galvanized sheet can be very thin, the minimum is 15g/m2, but If the coating layer is required to be thicker, the speed of the production line will be very slow, which is not suitable for the technological characteristics of modern units. Generally, the maximum is about 100g/m2. Therefore, the production of cold galvanized sheet material for metal stamping parts is greatly restricted; Galvanized sheet and cold galvanized sheet are fundamentally different in the structure of the coating. There is a slightly brittle compound layer between the pure galvanized layer of hot-dip galvanized sheet and the steel strip substrate. When the pure galvanized layer crystallizes, most of the zinc is formed. Flower, the coating is uniform and non-porous. The zinc atoms in the cold galvanized layer are only deposited and precipitated on the surface of the steel strip, and they are attached to the surface of the steel strip by physical action. There are many holes to dry, and it is easy to cause pitting corrosion due to corrosive media. Therefore, the hot-dip galvanized sheet of metal stamping parts It is more corrosion resistant than cold galvanized sheet; the heat treatment process of hot-dip galvanized sheet and cold galvanized sheet of metal stamping parts is also completely different. Hot-dip galvanized sheet generally uses chilled sheet as raw material, and continuous annealing and heating are carried out on the galvanized line. Galvanized, the steel strip is heated in a short time and then cooled, so the strength and plasticity are affected to a certain extent. Its stamping performance is worse than that of the same chilled plate after degreasing and annealing on a professional production line. The cold galvanized plate is made of cold-rolled plate, which basically guarantees the same processing performance as the cold-rolled plate, but its complicated process flow It also increases the production cost. In short, the production cost of hot-dip galvanized sheet is lower and the application range is wider; Recommended article: Common problems in the processing of stainless steel stamping parts Previous: What are the principles of stamping equipment selection for stamping parts processing plants?