Ductile iron development history

With its excellent performance, ductile iron parts can sometimes replace expensive cast steel and forged steel in use, and are widely used in the machinery manufacturing industry.

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Ancient China: In 1981, Chinese ductile iron experts studied 513 pieces of ancient Han and Wei ironware unearthed and concluded that spheroidal graphite cast iron appeared in my country during the Han Dynasty. However, because the technology at that time was difficult to produce in large quantities, this unique technique of ancient ductile iron has not been passed down.

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1940s: In 1947, the British H. Morrogh discovered that when cerium is added to hypereutectic gray cast iron so that the content is above 0.02wt%, the graphite becomes spherical. In 1948, A. P. Ganganebin and others from the United States pointed out that by adding magnesium to cast iron and then inoculating it with ferrosilicon, when the residual magnesium amount is greater than 0.04wt%, spherical graphite can be obtained. Since then, large-scale industrial production of ductile iron has begun.
Innovation of young Millis: The latest data shows that modern ductile iron was first successfully researched by K. D. Millis, a young researcher from the International Nickel Company (inco) in the United States. In 1942, Melis discovered that magnesium-added nickel-hard cast iron was significantly tougher than standard chromium-added nickel-hard cast iron, and its sulfur content was significantly reduced. In 1943, he added a nickel-magnesium alloy containing 20% ​​magnesium to the molten iron of a specific composition, and then added a ferrosilicon inoculant. After pouring the test block and cutting out tensile specimens and metallographic specimens, he found that complete ductile graphite had precipitated. The mechanical properties are very excellent, and this test marks the success of the formal research on ductile iron. Since then, inco has conducted pilot trials of the system under secrecy for five years.

Publication of Mohler's paper: Inco applied for a patent for magnesium-added ductile iron in 1947, but it was not until 1949 that Mohler of the British Cast Iron Research Institute applied for a patent for cerium-added ductile iron in the United States that the U.S. Patent Office did not substantively review Inco's patent. Review and approve the grant of relevant patent rights. Moller's research work and publication of papers promoted the disclosure and industrial application of modern ductile iron technology. In 1948, test blocks and castings were poured using inco technology for the first time, kicking off the industrial production of ductile iron.

NO.3

China's development: my country's ductile iron production started in 1950. At first, the copper-magnesium alloy punching method was used to develop ductile iron. From 1952, more units began to study the use of pure magnesium instead of copper-magnesium alloy, and used the bell jar pressing method to process ductile iron. In 1953, they mastered the method of adding molten iron. From 1957 to 1958, the methods of pressure addition of magnesium and volume reduction of magnesium were successfully tested and used in production. By 1958, my country's magnesium-based spheroidizing agents and their treatment processes were basically mature and complete. Ductile iron was initially used to make small parts and machine repair parts with low stress. The ductile iron crankshaft seminar in 1956 confirmed the reliability of the use of ductile iron crankshafts. Subsequently, some factories successively carried out relevant experimental research and put into production. Since 1958, due to the unique characteristics of the earth iron produced in large quantities in various places, the original magnesium-based nodulizing agent was not suitable. At that time, Baotou Steel successfully extracted cheap rare earths from the slag, providing raw materials for the rare earth nodulating agent. In 1964, relevant units used rare earth alloys and magnesium as composite spheroidizing agents to successfully develop rare earth magnesium ductile iron, which solved some defects in the production of magnesium ductile iron and put it into production. In 1965, a simple punch-in method was developed to replace the pressure magnesium addition method. Since then, my country's ductile iron has developed rapidly, with output increasing significantly year by year. A variety of new technologies and new varieties have been researched and developed, and relevant technical standards have been formulated.