In 1947, H. morrogh, an Englishman, discovered vermicular graphite in the process of studying the treatment of nodular cast iron with cerium. At that time and later, morrow’s research work mainly focused on how to obtain spherical graphite and its properties, while vermicular graphite is considered to be the product of failure in the treatment of nodular iron. In 1955, J. W. Estes and r. schneidenwind first proposed to use vermicular iron (vermicular iron for short); In 1966, R.D. schelleng continued to propose the application of vermicular iron. In a 1965 patent, the United States mentioned that the vermicular graphite structure can be obtained by adding an alloy to make the molten iron contain magnesium 0.05% ~ 0.06%, titanium 0.15% ~ 0.50% and rare earth metal 0.001% ~ 0.015%. By 1976, Foote mining company of the United States mixed these elements into mg Ti alloy in a certain proportion as a commodity supply market, which is called “Foote” alloy. Therefore, vermicular iron has been widely used in industry.
In the 1960s, the Austrians studied the effect of rare earth on molten iron and obtained a reliable method for producing vermicular iron. They obtained an Austrian patent in 1968. In the 1960s, China added rare earth ferrosilicon alloy to high carbon molten iron. It was found that the macro fracture of some samples was “spotted” and the graphite was worm like, and its performance exceeded the index of HT300 in the Chinese standard. In view of the shortage of medium and high-grade iron castings, the production of high-grade iron castings with rare earth alloy was not the starting point at that time. During the test, it is found that the strength of cast iron with vermicular graphite is greatly improved, so high-strength gray cast iron without scrap is obtained. Because the above high-grade cast iron is obtained by rare earth treatment, it has been named rare earth high-grade gray cast iron, rare earth (gray) cast iron, etc.
Since 1965, China has consciously studied and applied vermicular graphite as a new engineering material. In the late 1970s, according to the graphite morphology seen under the optical microscope and striving to unify the naming with foreign countries, China called it vermicular graphite cast iron, also known as vermicular graphite cast iron. The “vermicular graphite cast iron committee” was established at the 44th Annual International Casting conference in 1977. At the same time, it is also uniformly stipulated that the name of this kind of cast iron is “compact vermicular graphite cast iron”.