The damping, sensitivity, and thermal conductivity of ductile iron depend on the graphite's microstructure.

　　The damping, sensitivity, and thermal conductivity of ductile iron depend on the microstructure of its graphite and the metallic matrix. In gray ductile iron, a large amount of flaky graphite is present, creating numerous internal voids that significantly reduce the material's sensitivity to mechanical performance. Moreover, the extensive network of flaky graphite disrupts the matrix, enabling organized vibrational energy to propagate efficiently—ultimately converting this energy into heat and dissipating it. This is precisely why ductile iron exhibits excellent damping properties. On the other hand, the microstructure of gray cast iron consists of fine, rounded graphite particles embedded in a metal matrix, which remains largely intact without significant damage. As a result, gray cast iron is more sensitive to notches compared to ductile iron. Additionally, gray cast iron contains abundant thin graphite flakes, which enhance its thermal conductivity by facilitating efficient heat transfer. In contrast, ductile iron features round and spherical graphite shapes, lacking the flaky structure that promotes effective heat conduction. Consequently, ductile iron has poorer thermal conductivity than gray cast iron.

　　The purposes of inoculation treatment for gray cast iron are: to reduce the tendency toward white cast formation, minimize section sensitivity, promote graphitization, control graphite morphology, eliminate supercooled graphite, appropriately increase the number of eutectic groups, and encourage the formation of fine pearlite. For ductile iron, inoculation aims to eliminate supercooling tendencies, facilitate graphite spheroidization, and minimize interdendritic segregation. In contrast, the inoculation treatment for malleable cast iron is designed to promote the formation of cementite during the primary crystallization of molten iron, with no significant impact—or even an enhancing effect—on graphite formation during the subsequent graphitization annealing process. The key distinction lies in the fact that, during primary crystallization of malleable cast iron, cementite—not graphite—is expected to form instead.

　　The normal microstructure of ductile iron consists of a metallic matrix combined with fine, spherical graphite particles. In the as-cast state, the metallic matrix typically exhibits a mixed structure of pearlite and ferrite. Production steps include: melting qualified molten iron, performing spheroidizing treatment, applying inoculation treatment, conducting pre-furnace inspections, pouring the iron components, followed by cleaning and heat treatment, and finally, carrying out quality inspections on the castings.

　　Performance characteristics of vermicular graphite iron: 1. Strength and mechanical properties: Vermicular graphite cast iron exhibits tensile strength that is less sensitive to variations in carbon equivalent compared to ordinary gray cast iron. 2. Toughness and elongation: While vermicular graphite cast iron has lower impact toughness and elongation than ductile iron, it remains superior to gray cast iron. Notably, when the vermicularization rate is low or the matrix contains a high ferrite content, the material demonstrates enhanced toughness and elongation. 3. Thermal conductivity: The thermal conductivity of vermicular graphite cast iron primarily depends on the shape of the graphite flakes. When the vermicularization rate is high, the thermal conductivity closely matches that of gray cast iron; however, when the rate is low, the thermal conductivity approaches levels seen in ductile iron. 4. Excellent castability with good fluidity.

　　Molybdenum-iron alloy can be used to manufacture complex, large-scale components such as gearbox housings. Due to its superior mechanical properties and excellent thermal conductivity, it is often employed in parts that operate under conditions of heat exchange and significant temperature gradients—such as automotive brake discs.