By creating and stabilising long lasting particles which may then form the basis of nucleation, Preseed® preconditioner has been seen to give marked increases in the mechanical properties of castings as well as improvements to the graphite morphology / matrix. With careful use of Preseed®, foundries have been able to reduce expensive pig iron additions, create more stable and consistent castings and reduce overall costs.
There are very few dedicated preconditioners for cast irons available on the market. The need for more consistent base iron is increasing as the casting quality demands become more stringent. Based on fundamental research, Elkem has developed the preconditioner Preseed®. This has been demonstrated to improve the final casting properties of the iron and have a longevity far superior to other so-called preconditioning agents, such as silicon carbide or high barium containing ferrosilicons.
Preseed® has been shown to achieve a long lasting increase in the nucleation levels, raising the low eutectic temperature, reducing the degree of recalescence and increasing the graphite precipitation phase of the freezing cycle. The result in ductile irons is an increase in the nodule count and improvements in the resulting mechanical properties and shrinkage tendency.
In grey irons, Preseed® has been shown to improve graphite morphologies, reduce shrinkage and chilling tendencies, and improve mechanical properties. Elimination of undesirable graphite forms, such as type D and E graphites, has been achieved.
Topseed® cover alloy
Most foundries will use steel punchings or a standard ferrosilicon as a cover material on their MgFeSi addition to slow down the onset of the Mg reaction and allow a higher ferrostatic head to build up in the ladle. Neither FeSi75 or steel punching are very efficient.
Elkem has developed Topseed® as a cost effective treatment to maximise the recovery of magnesium whilst at the same time providing an increased level of nucleation in the iron.
Most reaction slags from nodularising treatments are liquid when the operators remove these from the ladle. This can be an inefficient and environmentally unfriendly process with many airborne particles from unexpanded perlite based coagulants. The addition of barium as a part of the Topseed® composition changes the slag phases to a solid and more easily removed dross. This also encourages the slag to precipitate in the treatment ladle rather than further down the casting process and cleaner stopper rods, pouring vessels and less dross inclusions result.
Preseed® and Topseed® are registered trademarks of Elkem AS