The use of magnesium additions in ductile cast irons
Elkem introduces “Topseed® cover alloy” - another big step forward in reducing magnesium addition and lowering production costs in ductile iron foundries.
The use of magnesium ferrosilicon (MgFeSi) to nodularise cast irons is a significant cost for ductile iron foundries. This is why Elkem has developed Topseed® as a new cover alloy to maximise the recovery of magnesium and, at the same time, give higher levels of nucleation and improvements in process stability.
Topseed® cover alloy has been specially formulated to;
Increase magnesium recovery.
- Use of a high density cover for MgFeSi in the ladle pocket delays the onset of reaction, allowing a greater ferrostatic head and thus more contact between the magnesium vapour and the cast iron
Condition the slag.
- Use of Topseed® cover alloy gives a dry slag which is easy to skim from the metal surface. Slag is precipitated in the ladle rather than in subsequent pouring operations.
Increase nucleation levels in the treated iron.
- Increases in magnesium recovery means that either a lower Mg containing alloy can be used or the addition rate can be reduced. Lower requirement for magnesium, combined with the nucleating elements in Topseed® cover alloy, mean that nucleation levels in the iron are higher. This can lead to a decrease in subsequent inoculation requirement.
Improved process stability.
- Topseed® cover alloy is a dense material based on maximum 50% silicon, and, in its closely graded sizing, provides a close packed cover on the MgFeSi. Variables such as steel scrap sizing and thickness, pouring times, premature reaction due to poor coverage are eliminated to give more consistent recoveries of magnesium
Topseed® cover alloy is a dense material based on maximum 50% silicon, and, in its closely graded sizing, provides a close packed cover on the MgFeSi.
The alloy is endothermic and thus provides a short term barrier to cast iron burning through to reach the MgFeSi. This allows for a greater ferrostatic head in the ladle therefore increasing the contact between the magnesium vapour and the cast iron. The use of properly designed pockets can lead to very high Mg recoveries, particularly when used in conjunction with Elkem’s extensive range of nodularisers.
Recent comprehensive tests in foundries have shown a reduction in MgFeSi addition of up to 20% due to excellent Magnesium recovery.
Elkem manufactures the largest number of MgFeSi chemistries in the world and can tailor an alloy to your specific needs. These, under the trade names Lamet ®, Remag® and Elmag® nodularisers and in combination with Topseed® cover alloy, provide you with optimum alloy usage at lowest cost.
Elkem’s experienced representatives and technical service team can help in designing the best system of alloys for you to give the best value from our range of Preconditioners, Nodularisers, Inoculants and Cover Materials.