Ductile iron is an important kind of strong and tough cast iron, which has been fully used in heavy and large load-bearing structural parts such as engineering machinery, energy machinery, national defense and military industry. Especially in the environment with high requirements for plasticity, toughness and anti-seismic wear resistance, the parts made of ductile iron castings can not only meet the requirements of greater stress, but also withstand vibration and impact, and the manufacturing cost is much lower than that of steel castings. Since the invention of ductile iron in 1947, it has been developed rapidly at home and abroad. At present, the output of ductile iron has exceeded that of steel castings.
In the field of ductile iron casting industry, the castings with section wall thickness greater than 100 mm are usually called thick section ductile iron. In terms of research results of Heavy Ductile Iron, some developed countries abroad have higher technical level and production strength. Siempelkamp company of Germany has successfully developed the castings for nuclear spent fuel storage and transportation vessels, which is one of the typical representatives of the highest international production level of Heavy Ductile iron. The outline dimension of the container casting is Φ 2500mm × 5976mm, the maximum wall thickness is 400mm, the tensile strength is required to be 300mpa, and the low temperature impact energy at – 40 ℃ is required to reach 12j / cm2. These indexes and data are difficult to control and realize in the actual production engineering technology.
GE company of the United States and Dalian Heavy Industry Co., Ltd. have achieved success in the research of large-scale wind power (6MW) rotor casting, which represents the current domestic leading nodular cast iron casting technology level. The casting contour size is up to 6900 mm, which belongs to the high difficulty large thin-walled casting. Dalian heavy industry has also become the exclusive supplier of this key component in China.