ELMAG® NODULARISERS - Elkem

ELMAG ® NODULARISERS• A wide range of MgFeSi grades to accommodate each foundry’s treatment process• Speciality treatment alloys for specific applications in the foundry industry• Narrow product specifications to give highest consistency of Mg recovery• Improved nodule counts, nodularity and structures• Cost effectiveElkem’s Commitment to MgFeSi ProductionProducers of magnesium ferrosiliconalloys traditionally manufacture only afew chemistries and tend to be locatedin one geographic region. Elkem hasstrategically built specialist plantsclose to the major casting regions toprovide a rapid and reliable service toour customers. By staffing the plantswith people who understand the localcustomer requirements, Elkem is ableto give top quality service and support.Elkem Bjølvefossen is located on thewest coast of Norway and has traditionallybeen the major supplier to theEuropean foundries. Certified to ISO9001 and ISO 14001, widely regardedas one of the premier MgFeSi productionplants in the world.With ductile iron production predictedto grow in the coming years, Elkem hascreated additional lapacity at ElkemIceland. Positioned between Europeand the Americas, and certified withISO 9001, Elkem Iceland is able tosupportment growing demand on bothcontinents when needed. This demonstratesclearly Elkem’s long term commitmentto the iron foundry industry.Elkem Chicoutimi in Canada serves theNorth American markets. The plant iscertified with ISO 9001 and ISO 14001and is capable of supplying the largevolumes of quality MgFeSi demandedby foundries in this region.Elkem Foundry China supplies highquality MgFeSi to the huge domesticindustry in China. Whilst there are manyproducers in this growing economy,Elkem’s consistency has seen themost quality oriented foundries turn toElkem as their preferred supplier. ElkemFoundry China holds certification ISO9001 and OHSAS 18001.Elkem Elmag ® NodularisersMgFeSi should be regarded as a specialityproduct in today’s environmentof tight production schedules andquality requirements for cast ironfoundries. Elmag ® nodularisers areproduced to narrow specificationscompared to other materials availableon the market. This ensures that thealloy recovery and consistency of theiron treatment process are maximised.Elmag ® nodularisers are 50% Si basedferroalloys produced to a wide rangeof specifications with defined levels ofmagnesium, calcium, rare earth metals(RE) and aluminium. Elkem pro ducesclose to 100 different chemistries, eachof them being available in various sizes.This means that Elkem can offer a rangeof treatment alloys to suit the needs ofjust about every foundry productioncondition.Elmag ® , Lamet ® and Remag ® are registered trademarks of Elkem AS. CompactMag TM is a trademark of Elkem AS.

Elkem Speciality Treatment AlloysIn addition to the wide range of Elmag ®nodularisers, Elkem has, as a result ofextensive research and foundry trials,developed highly specialised treatmentalloys for specific applications in thefoundry industry:Lamet ® NodulariserConventional MgFeSi alloys can haveseveral disadvantages when used asin-the-mould nodularising agents. Promotionof shrinkage porosity and generationof inclusion defects are knownproblems. Use of Lamet ® nodulariser,which is very low in slag promotingelements, is an effective way of makingclean ductile iron castings and promotesa lower shrinkage tendency. Lamet ®nodulariser is available in two forms:• Lamet ® 5504 nodulariser is designedspecifically for in-the-mould productionof ductile iron, with very low oxidecontent and standard sizing of 1 – 4mm. Refer to the product brochure“Lamet ® nodulariser in-the-mould”.• Lamet ® nodulariser with conventionalcalcium contents, but with lanthanuminstead of misch metal as the rareearth source serves as an excellentalternative to standard MgFeSigrades. Lamet ® ladle grades offerslower tendency of micro shrinkageand chill.Refer to the productbrochure “Lamet ® nodulariser ladlegrades”.Remag ® nodulariserRemag ® nodulariser contains carefullybalanced levels of either misch metalor cerium as the source of RE and isdesigned to give high nodule countsand minimal chill in thin section ductileiron. In conjunction with Elkem’s extensiverange of inoculants, excellentcasting properties may be more easilyproduced in this notoriously difficultarea of production. The lower levels ofmagnesium, coupled with the higherlevels of RE give a high recovery ofactive elements with low reactionviolence.CompactMag alloyCompactMag alloy is specificallydesigned for the production of compactedgraphite iron (CGI). The alloycontains balanced levels of RE andmagnesium to give minimal structuresection sensitivity coupled with a highpercentage of compacted graphite.Less prone to sulphur and chemistryvariations than either “undertreatment”or the Ti production routes, Compact-Mag alloy is the optimum method forCGI production. Being Ti free, thereturns may be mixed with other foundryreturns without fear of con ta mination.Refer to the product brochure “CompactMagalloy”.Production of Elmag ® MgFeSiFerrosilicon alloys that contain ele mentssuch as Mg, Ca, Al and RE have complexstructures consisting of a numberof intermetallic compounds. The solidification temperatures of these compoundsvary and this can lead toextensive segregation if the alloy isallowed to cool slowly during casting.Because some of these compounds aremore brittle and crush more readily, thiscan lead to wide variations in compositionsof different particle sizes aftercrushing and grading.At the Elkem plants, Elmag ® MgFeSialloys are cast into thin slabs in ironmoulds. This produces a very finestructure and avoids any risk of segregationoccurring during solidification.The composition of these products istherefore consistent over the entirerange of particle sizes. An example ofphase composition is shown in Figure 1.Figure 1: Typical phases in MgFeSialloys. The formation of a more thermodynamicallystable CaMgSi 2phasereduces reaction violence comparedto the reactive Mg 2Si phase. Excesscalcium can, however, increase slaggeneration.

Effects of Alloying Elements in MgFeSiMagnesiumMagnesium is the principal elementused for production of ductile iron.With a boiling point of only 1190°C, atleast 200°C below the usual castingtemperature of cast irons, the mostcommon method of introduction is bymeans of a ferrosilicon based carrier.The use of such an alloy, magnesiumferrosilicon, allows for the introductionof other beneficial elements at thesame time, such as rare earth metalsand calcium.Magnesium has the effect of allowingthe precipitated graphite to form asdiscrete nodules, thus converting greyiron into ductile iron, which allows theiron matrix to control the mechanicalproperties of the iron. Unfortunately,excess residual magnesium in the ironhas the negative effects of introducingiron carbides (chill), reducing nodulenumber and promoting shrinkage. Thusthe consistent control achieved withElmag ® nodularisers is essential for asuccessful production of ductile iron.Rare Earth MetalsTrace elements such as antimony, lead,bismuth and arsenic occur in the chargematerials used by most iron foundries.These elements prevent the formationof nodular graphite by magne sium andtend to produce degenerated graphiteforms. The detrimental effects can beneutralised by minor amounts of rareearth metals (RE) in the iron. By includingRE in the MgFeSi alloy, separateadditions are avoided. RE enhancesgraphite nucleation and has good faderesistance, thus giving a higher nodulecount after inoculation. In excess, REcan give increased chill tendency andundesired graphite forms such aschunky and exploded graphite.Foundries using high purity chargematerials may not require the presenceof rare earths and will gain technicaland economic advantages by usingElmag ® nodularisers without rare earthadditions. For the production of thicksection parts, the MgFeSi could haveno, or very little, rare earths. Such specialistalloys are available within theElkem range of products.CalciumThe presence of small amounts ofcalcium in MgFeSi alloys reduces thereactivity of magnesium, thus minimisingfume emission and improving themagnesium yield. Ca helps to initiatethe modification process by reactingwith S and O forming sulfide and silicatephases. The effect is a high degree ofnucleation and a good growth rate ofgraphite nodules giving a higher nodulecount. As Ca increases the tendencyto slag formation, the amount of Ca inthe MgFeSi needs to be adjustedaccording to the treatment process.AluminiumAluminium occurs in small amounts inmost ferrosilicon alloys unless deliberatelyavoided. Al in the correct amountsreduces undercooling and shrinkagetendency and if the base Al contentis low, a small addition of Al improvesinoculation. Al may also increase ferritecontent in ductile iron. Excess Al promotesH-pinholes as a higher contentof hydrogen can be dissolved in thecast iron melt. The solubility of hydrogendecreases with decreasing temperatureduring casting, and the dissolvedhydrogen in excess is then precipitatedin the form of pores.Application of Elkem Treatment AlloysElmag ® nodularisers and specialitytreatment alloys are designed to meetthe needs of every foundry productionElkem ASFoundry ProductsHoffsveien 65BP.O. Box 5211MajorstuenN-0303, Oslo, NorwayTelephone : +47 22 45 01 00Telefax : +47 22 45 01 52www.foundry.elkem.commethod, from open ladles to the mostadvanced tundish systems, fromflowthrough systems to in-the-mouldtreatment. As well as ladle design,pouring temperature, casting requirement,etc.The ability to vary Mg, Ca, RE andAl levels mean that, if not currentlyavailable, Elkem can produce an alloyspecifically for individual customers.A number of factors influences on thechoice of nodulariser for a particularfoundry, as well on the addition rateof MgFeSi. Refer to Elkem TechnicalInformation Sheets No. 20 and 23 forgeneral guidelines on these importantissues. Specialist advice on selectingthe optimised alloy chemistry andsizing for your production method isreadily available from Elkem’s salesrepresentatives.Revised April 2012 © Copyright Elkem AS