Magnesium is added to ductile iron as a nodularizing agent, which helps to form graphite nodules within the iron. These nodules improve the strength, ductility, and toughness of the iron, making it more suitable for a variety of industrial applications.
Magnesium increases the strength and ductility of ductile iron by promoting the formation of graphite nodules. It also helps to reduce the formation of undesirable graphite forms, such as flakes, which can weaken the iron. Additionally, magnesium can improve the impact resistance and fatigue strength of ductile iron.
The optimal amount of magnesium to add to ductile iron varies depending on the specific application and desired mechanical properties. Generally, a magnesium content of 0.03-0.06% is recommended, but it is important to consult with a metallurgist to determine the exact amount needed for your specific application.
While magnesium is essential for the production of ductile iron, there can be some potential drawbacks. Excess magnesium can lead to the formation of undesired graphite forms, such as chunky or exploded graphite, which can weaken the iron. It is important to carefully control the amount of magnesium added to ensure optimal results.
The addition of magnesium can increase the cost of producing ductile iron due to the cost of the magnesium itself and the extra processing steps needed to ensure proper nodularization. However, the improved mechanical properties and overall quality of ductile iron make it a valuable and cost-effective material for a variety of industrial applications.