The copper mould tube of the crystallizer of the continuous casting machine is the heart component of the continuous casting machine. During continuous casting, the molten steel passes through the copper tube of the mold to achieve a cooling effect. The molten steel from the mold hardens into a shell.
Due to the current high drawing speed, serious wear on the inner wall of the copper tube. When there is no coating, the bare copper matrix will affect the quality of the billet and even fall off. Therefore, the inner wall of the mold copper tube is required to have a high-quality coating. In the original process, a layer of chromium is electroplated on the inner wall of the copper tube. Because the thermal expansion coefficient of chromium is too different from that of copper, the chromium layer will fall off due to the heat of the copper tube during use. After the layers fall off, the desired effect cannot be achieved. The amount of steel passing is about 4000 tons at most.
According to the electroplating workers, the use environment of the copper pipe adopts a process of first plating a layer of nickel-cobalt alloy and then chromium plating, referred to as composite copper plating pipe. The nickel-cobalt alloy electroplating process can solve the problem of the chromium layer falling off, and at the same time, it has a good bonding force with the substrate. Since the thermal expansion coefficient of the nickel-cobalt alloy is between copper and chromium, it serves as a buffer.
At the same time, in nickel-cobalt alloys, cobalt is resistant to high temperature and wear. Even if the chromium layer falls off, the steel can be pulled. In addition, when the nickel-cobalt alloy is around 500°, it transforms into a magnetic coating, which increases wear resistance. Therefore, the amount of steel passing has increased significantly, and the amount of steel passing is generally around 6000 tons. 2000 tons more than a single chromium layer.
In order to completely solve the peeling off of the electroplating layer of the copper tube of the continuous casting mold, the world’s latest technology is used to electrodeposit the nickel-cobalt-iron plating layer instead of chromium. The steel capacity can reach 10,000 tons.