What is the purpose of galvanized surface of nodular cast iron
Release time：
2023-02-15
Ductile iron is a kind of high-strength cast iron material. Its inductive function is close to that of steel. Based on its excellent function, it has been successfully used to cast some parts with complex stress and high requirements for strength, durability and wear resistance. Ductile iron has rapidly developed into a very widely used cast iron material next to gray iron.
Ductile iron is a kind of high-strength cast iron material. Its inductive function is close to that of steel. Based on its excellent function, it has been successfully used to cast some parts with complex stress and high requirements for strength, durability and wear resistance. Ductile iron has rapidly developed into a very widely used cast iron material next to gray iron. The so-called "replacing steel with iron" mainly refers to nodular cast iron. The function of nodular cast iron is close to that of carbon steel, but its casting function is good and easy to form, its processing function is better than that of cast steel, and it is more heat-resistant, corrosion-resistant and wear-resistant than that of steel. Ductile iron has lower tensile strength, plasticity and resistance than carbon steel. Although the mechanical function of nodular cast iron is not as good as that of steel, due to the existence of graphite, nodular cast iron is endowed with many functions that are inferior to that of steel. In addition, its carbon content is high, and its composition is close to the eutectic composition, so its melting point is low, about 1200 ℃, and the molten iron fluidity is good. Due to the large volume expansion of graphite during crystallization, the transmission shortening rate is small, and its casting function is better than that of steel. Therefore, it is usually used to make castings by casting method, so it is called nodular cast iron. So, do you know the special purpose of galvanization on the surface of nodular cast iron? Let's take a closer look: The reason why ductile iron castings can defeat other workpieces and become the materials used in many occasions is that they have strong compression resistance and excellent anti-corrosion function. The anti-corrosion function comes from the galvanized coating on the surface of the product. When the electrochemical reaction between zinc and iron is delayed, a stable maintenance layer will be formed on the surface of nodular cast iron, which will play an active maintenance effect on the product. In addition, when the zinc coating on the nodular cast iron is in contact with the soil, the metal zinc will gradually transform into a tight, cohesive and continuous zinc salt layer, which is an insoluble substance. Another reason for galvanized ductile iron castings is that it can form an active repair and maintenance layer at the damaged part to ensure the integrity of the workpiece. In this way, the corrosion problem of ductile iron castings has been well solved. To put it simply, galvanizing is to avoid corrosion of nodular cast iron, and has a maintenance effect on it. The above is the reason why the surface of nodular cast iron should be galvanized. Other matters should be noted: during the manufacturing of nodular cast iron, the coarse sand and oxide skin on the surface should be cleaned, and the riser, vent hole, fleshy, flying wing and burr should be removed. The machined surface is allowed to have appearance defects within the margin range, but it is not allowed to have casting defects (such as cracks, cold shuts, shrinkage holes, slag inclusion, etc.) that affect the application function of the casting.
Related news
Haian Aoyu Machinery Manufacturing Co., Ltd.
Address: No.188 Xingnan Road, Nanmo Town, Haian City, Nantong, Jiangsu, China
E-mail：511671240@qq.com
Mobile terminal
Copyright © 2023 Haian Aoyu Machinery Manufacturing Co., Ltd.