By covering magnesium-ferrosilicon nodulizers in the ductile-iron treatment ladle, Topseed® cover alloy delays the magnesium reaction, reducing flare and increasing magnesium recoveries. Once the magnesium reaction is finished, the strong inoculating elements in Topseed® cover alloy promote a fully-nucleated ductile-iron structure, minimizing the risk of forming hard carbides that are difficult to machine.
Of the three cover alloys now offered by Elkem, most foundries will use Topseed® 1010 cover alloy, which has the calcium, aluminum, and barium levels that provide optimum inoculation, fade resistance, and slag conditioning. For foundries making small additions or desiring additional fade resistance and slag conditioning, Elkem now offers high-barium Topseed® 2005 cover alloy with reduced aluminum levels. For foundries wanting to limit the build-up of hard aluminates in the holding furnace or treatment and pouring ladles, Elkem also supplies Topseed® 1005 cover alloy, which contains only 0.8% maximum aluminum.
Ductile-iron foundries can maximize magnesium recoveries and reduce treatment costs by combining Topseed® cover alloy with low-magnesium nodulizers like Elkem’s Lamet® magnesium-ferrosilicon. Many foundries are using Lamet® magnesium-ferrosilicon as a pound-for-pound replacement for higher-magnesium nodulizers — a practice that substantially reduces treatment costs. Further savings can be made with this practice because low-magnesium nodulizers reduce slag volumes, lower furnace- and ladle-lining costs, reduce defect losses, and improve productivity.
Elkem technical personnel are available to work with ductile-iron foundries to help design a ladle pocket that optimizes the use of Topseed® cover alloy and magnesium-treatment alloys.Picture: A quieter reaction takes place in the ductile-iron treatment ladle when Elkem’s Lamet® magnesium-ferrosilicon is covered by Topseed® cover alloy in the ladle pocket. This practice gives higher magnesium recoveries and lower costs.