Jun. 16, 2021
Advantages Of Ductile Iron
Ductile iron is very strong compared with ordinary cast iron (gray cast iron). The tensile strength of cast iron is 20,000 to 60,000 pounds, while ductile iron starts at 60,000 pounds and can go up to 120,000 pounds. Ductile iron usually has a yield strength of 40,000-90,000 psi, but the yield strength of cast iron is so low that it cannot be measured.
Let's use our power in a different way. We have seen that gray iron parts can break when they fall ten feet and hit the ground. With ductile iron castings, you can hit parts with an eight-pound octagon hammer all day and never break.
The cause of the gray iron problem is that the graphite scales contribute to the fracture of the graphite sheets, while nodular nodules in ductile iron hold the iron together. Given the exact same case of the same part made of two different metals, brittle gray cast iron wants to crack and ductile cast iron wants to bend.
Because of the graphite in ductile iron, ductile iron also has excellent wear resistance. When you rub on ductile iron, ductile iron wears away much more slowly than many other metals. The wear resistance comes in part from the graphite structure, which acts on iron like a dry lubricant.
Ductile iron also dissipates heat very well and can be machined easily, although ductile iron is more difficult to process than ordinary gray cast iron. Ductile iron has better damping vibration and sound effects than steel, making it ideal for use on large machines.
Difficulties in the production of ductile iron
Due to the thick section of this type of casting, the cooling is slow, the solidification time of the liquid metal is long, and the inside of the casting is prone to shrinkage porosity. In the production of ferritic ductile iron, in order to obtain higher tensile strength, yield strength, and elongation, fertilizing heat treatment has been used in the past. The heat treatment temperature is based on whether there is free cementite or pearlite in the as-cast structure. , While using 900-950℃ high-temperature heat treatment. However, the high production cost, complex process, and long production cycle bring great difficulties to the production organization and delivery date, which requires that the ferrite matrix must be obtained in the as-cast state.
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