Why choose ductile iron castings?

Ductile iron is not a single material but part of a group of materials that can be produced with a variety of properties by controlling the microstructure. The common defining characteristic of this group of materials is the shape of graphite. In ductile iron, the graphite is in the form of spheroids rather than the flakes found in gray cast iron. The sharp shape of the graphite flakes creates stress concentration points within the metal matrix, while the rounded nodules do not create stress concentration points, thereby inhibiting the development of cracks and providing enhanced ductility, which is how the alloy gets its name. The formation of spheroidizing elements is achieved by adding spheroidizing elements, most commonly magnesium (note that magnesium boils at 1100°C and iron melts at 1500°C) and less commonly nowadays cerium (usually in mixed rare earth form ). Tellurium is also used. Yttrium, often a component of mixed rare earths, has also been studied as a possible nodulizing agent.

Ductile cast iron obtains spherical graphite through spheroidization and inoculation treatment, which effectively improves the mechanical properties of cast iron, especially its plasticity and toughness, thereby obtaining higher strength than carbon steel. Ductile iron is a high-strength cast iron material developed in the 1950s. Its comprehensive performance is close to that of steel. Due to its excellent performance, ductile iron has been successfully used to cast components with complex stress, strength, toughness and wear resistance. Ductile iron has rapidly developed into the most widely used cast iron material after gray cast iron. The so-called "replacing steel with iron" mainly refers to ductile iron. Ductile iron is commonly used in the production of crankshafts and camshaft parts for automobiles, tractors, internal combustion engines, and medium-pressure valves for general machinery.