carbon content and cast iron types

Cast iron refers to a multi-element iron-based alloy with carbon content greater than 2.11% and more elements such as silicon, manganese, sulfur, and phosphorus; cast iron has a simple production process and low cost, and is one of the earliest and most widely used materials. According to different focuses, cast iron can be divided into several categories.



According to the form of carbon, it can be divided into white cast iron, gray cast iron, and pitted cast iron. The carbon in white cast iron exists in the form of Fe3C, no graphite, and the fracture is silver-white; it is hard and brittle, and has fewer uses. Now it is mostly used as anti-wear parts, such as agricultural tools, grinding balls, and machine parts with low toughness requirements. It can also be used as a raw material for smelting steel. White iron generally contains 2-3.6% carbon and alloying elements such as Cr, Mo, Cu, Al. According to the chemical composition, it can be divided into ordinary cast iron and alloy cast iron. Adding a small amount of alloying elements to ordinary white cast iron can increase the hardness of carbides and improve wear resistance.

Gray cast iron has a carbon content of 2.8-4.0%, and its fracture often appears gray-black, and a large amount of flake graphite is dispersed in the gray cast iron. Its molten iron has strong fluidity and good pouring performance, and is widely used in castings with more complex structures. Compared with ordinary steel, gray cast iron has poor tensile properties, but its cutting performance and wear resistance are higher. The production cost is also lower. After using inoculant for processing, its performance can be further improved.

Pitched cast iron is abbreviated as pockmarked iron, which is a mixed structure of gray and white cast iron. Pitched cast iron is that the carbon in the pockmarked cast iron exists both in the form of cementite and in the form of graphite. The fracture is mixed with white free cementite and dark gray graphite. The fracture is off-white and brittle, it is rarely used.