As one of the best materials to replace steel, ductile iron was discovered by humans in 1949, and was quickly used by valve manufacturers after that. Steels with a carbon content of less than 0.3%, cast iron and ductile iron and a carbon content of at least 3%. The presence of graphite lamella structures of free carbon in steelmaking with low carbon content is not formed. Carbon is the natural form in iron in the form of free graphite flakes. In ductile iron, it is specially processed into fine flakes of graphite nodules. This allows the ball to compare with an improved ratio of ductile cast iron and steel with more excellent physical properties. This is the spherical microstructure of carbon, with more toughness so good ductility and impact resistance, and the cast iron on the inside of the sheet causes no ductility in the table. The optimum ductility is obtained from the ferritic matrix, therefore, the load pressure of the ductile iron is in the intermediate annealing cycle of the ferrite, the ductile structure of the cast iron within the spherical structure, post-treatment, can easily eliminate the resulting stone. The phenomenon of internal cracks in the ink sheet when the valve is manufactured. In the microphotograph of ductile iron, it can be seen that after the cracks in the process, the graphite nodules terminate. In the ductile iron industry, these so-called graphite nodules are "crack terminators" because of their ability to prevent breakage.
Compared with cast iron, ductile iron has an absolute advantage in strength. The tensile strength of ductile iron is 60K, while the tensile strength of cast iron is only 31K. The yield strength of ductile iron is 40K, while iron does not show yield strength and ultimate fracture occurs. Strength ductile iron - cost ratio is far superior to cast iron.
Ductile iron castings are comparable in strength and strength. Ductile iron has a higher yield strength, with a minimum yield strength of 40K, and steel has a yield strength of only 36K. In most municipal applications, such as: water, salt water, steam, etc., ductile iron is more resistant to corrosion and oxidation than steel. Due to the microstructure of ductile iron, ductile iron has a strong ability to weaken vibration and is more ductile than steel, so it is more conducive to reducing pressure. One of the important reasons is the low cost of cast ductile iron casting ductile iron. The cost of the ductile material makes this more popular, the casting is more efficient, and the cost of machining ductile iron is less.