It has been 52 years since ductile iron appeared, and its rapid development is surprising. Even in the case of economic depression, ductile iron is still developing. Some people call ductile iron the winner in improper retreat. It is pointed out that ductile iron still plays an important role in the material market because of its high strength, high toughness and low price. Although the total output of steel castings has declined in recent years, the output of ductile iron has not declined, and the appearance of austenite-bainite ductile iron has enhanced the competitiveness of ductile iron. 1. 1 Production and research status of nodular cast iron. 1 conventional ductile iron At present, conventional ductile iron, that is, ductile iron mainly composed of ferrite and pearlite, still accounts for the vast majority of the output of ductile iron, so it is important to pay attention to improving the performance and quality of conventional ductile iron to maintain its competitive position. 1. 1. 1 Strengthen the control of factors affecting the quality of ductile iron. The microstructure and properties of ductile iron depend on the composition and crystallization conditions of cast iron and the quality of nodulizer used. It is considered that in order to ensure the mechanical properties of ductile iron, it is necessary to strictly control the specific wall thickness, pouring temperature, spheroidizing agent used, spheroidizing treatment process, optimization of cooling parameters and effective slag removal measures, and appropriately reduce carbon equivalent. 1. 1.2 Effectively control the production of ferritic ductile iron and nodular cast iron [2] The main factors to control the matrix of nodular cast iron are the composition of cast iron, the types of nodulizer and inoculant used, the adding method and cooling conditions. The composition of as-cast ferritic ductile iron is slightly higher than that of * * * crystal, in which carbon is slightly higher, but graphite does not float and silicon content is slightly lower. The silicon content of inoculants should be less than 3%, and the lower the manganese content, the better. manganese