The Development History of Ductile Iron

According to modern archaeological research, a large number of cast iron related relics and artifacts have been discovered at the Back Bay Cast Iron Site in the ancient city of Zhenghan, Xinzheng. The Back Bay Cast Iron Site is located in the southwest of Dongcheng District, Zhenghan Ancient City, Xinzheng City, with an area of nearly 100000 square meters. This site is an official handicraft workshop for casting tools and farming tools in the capital city of South Korea during the mid to late Warring States period. The decarburization kiln was first discovered at the Wanwan Cast Iron Site in Henan Province, which advanced the history of ductile iron in China by at least 200 years. At least 2000 years earlier than the West.

Reaumur from France made white heart malleable iron in 1722. Later, Seth Boyden of the United States invented blackheart malleable iron in 1826.

In the 1920s. Due to advances in research on the main components such as carbon and silicon in cast iron, as well as the effects of adding other alloying elements, melting methods, and inoculation effects, the so-called advanced cast iron has emerged. Therefore, there has been a considerable improvement in the material and to some extent, the application scope has been expanded. However, due to the fundamental drawback of low toughness, its application scope has not been rapidly expanded.

In 1947, the British man Morrogh discovered cast iron with spherical graphite in the as cast state.

In 1948, ductile iron was produced by adding Ce to high carbon, low sulfur, and low phosphorus gray cast iron and keeping its residual amount above 0.02%. Almost at the same time, American International Nickel Company (INCO) and others obtained the same ductile iron by adding Mg to the cast iron and keeping its residual amount above 0.04%.

During World War II, due to the lack of chromium resources necessary for producing wear-resistant martensitic white cast iron, researching alternative elements for Cr became an urgent task. Therefore, systematic investigations and studies have been conducted on whether various metals and transition metals that chemically bind with carbon can form carbides, including magnesium. In order to mitigate the intense splashing during magnesium addition, Cu80-Mg20 alloy and Ni80-M920 alloy have been used. The results indicate that magnesium not only has a good effect as a substitute element for chromium, but also has a significant desulfurization effect when there is a certain degree of residual magnesium in the molten iron. Based on these new discoveries, the effect of adding magnesium to gray cast iron has also been studied, following white cast iron. Adding 0.5% Mg to gray cast iron containing 3.5% C, 2.25% Si, and 2% Ni, its tensile strength far exceeds the original expectation (ordinary gray cast iron is about 13kgf/mm2), reaching up to 78kgf/mm2.