Pyrotek's 4th International Metal Quality Workshop

CASTHOUSEPyrotek’s 4th International MetalQuality WorkshopThe 2008 International Metal Quality Workshop (MQW4) took place in May in Istanbul reflecting theemergence of Turkey as a major player in global aluminium production. 320 delegates attended from19 countries, the largest gathering since establishing the event in 2001.Since 2001, Cast House equipmentspecialists, Pyrotek, have beenconducting regular workshops andseminars to invited audiences notonly to inform customers and potentialcustomers of Pyrotek’s technologies in thisfield but, more importantly, to obtain anexchange of information betweencustomers and supplier to identify areasthat require development or enhancementof technologies to enable the Cast Houseto supply cleaner metal and more preciselyto chemical and metallographicspecification.The 2008 International Metal QualityWorkshop (MQW4) took place in May inIstanbul reflecting the emergence ofTurkey as a major player in globalaluminium production. Indeed, AssanAlüminyum, Turkey’s largest producer,was the local host and co-sponsor of theevent.330 delegates and speakers attended theevent from 39 countries (80 fromTurkey) plus 40 Pyrotek specialists andsome 30 partners who took part in aseparate site-seeing programme duringthe day and attended the nightly socialfunctions. This made it the largest MQWevent so far exceeding the 260 delegatesattending the previous event held inDubai in 2005 and those in Prague (2003)and the inaugural meeting in Madrid(2001). Simultaneous translation wasoffered in Turkish and Russian alongwith co-projection of slides translatedinto these languages, as well as personaltranslators for those delegates fromChina. Fourteen of the 16 presentationswere also published as slides in English,Turkish and Russian on CDRom.Two of Pyrotek’s top technicalpersonnel chaired all sessions, JonathanPrebble, Manager Aluminium ProcessTechnology and Dr Neil Keegan,Manager Metallurgical Services Group.An extra day had been added to thisyear’s event making it four in totalconsisting effectively of two days ofpresentations and two days of break-outsessions where delegates could chose thetopics of greatest interest to them from aselection of 15 small group discussionsand 12 more structured workshops.Adequate time was also given during theone hour coffee and lunch breaks forfurther discussion.Day 1 was the ‘extra’ day focussing onconsumables and had been added inAllan Roy, President & CEO Pyrotek with Bahadir Ozer Vice President Assan Alüminyumco-sponsors of the eventresponse from feed-back from the Dubaievent. Hence, the event was not officiallyopened until the second day when AllanRoy, President & CEO Pyrotekwelcomed all attendees.Day 1 commenced with an address byJonathan Prebble outlining the objectivesand structure of the workshop whichconsisted of 12 case studies, two openingand closing plenary lectures – bothfocussing on the transport market – butmysteriously referred to as ‘case studies’and the break-out sessions.Jonathan Prebble outlined theparameters to be controlled to achieve aquality melt whether from primary potroomaluminium or secondary remeltedaluminium as well as the efficientoperation of a cast house. He identifiedthese parameters as: Cycle times; Costs;Temperature; Cleanliness; Chemistry;Structure; Flow rate; Handling;Degassing; and Filtration. For example,avoid unnecessary overheating the meltwhich wastes fuel and so increases costs;minimise cycle times by ensuring allequipment is ready to receive theincoming metal; minimise furnacecharging time and heat loss by ensuringthe charge is to hand and the furnace dooris only opened as the charging vehicleapproaches the furnace. The majority ofthe suggestions were practical ‘commonsense’ approaches requiring little or nocapital costs but sadly often overlooked indaily operation, he concluded.Break-out sessions followed with threeone and a half hour workshops coveringBillet Casting, Continuous Casting andIngot (rolling slab) casting, each led byone or more specialists in those particulartechnologies. Each session consisted of ashort presentation on the topic – severalof which were to be reinforced in theCase Study presentations on subsequentdays – followed by a questions anddiscussion with the participants. Severalproblems were posed by delegatesseeking solutions to various problemsthey had encountered, some receivingadvice that they hoped to implement onreturn to plant, but others having alreadytried all the suggestions proposed wereencouraged to seek further advice fromthe appropriate Pyrotek representative. Anumber of the problems appeared torelate to the quality of the cooling waterused in Direct Chill (DC) casting, forexample through contamination withmould lubricant which dramaticallyreduces its cooling effect – the use of oilrather than grease was recommendedhere as a means of reducingcontamination, or problems when locatedin regions of high ambient temperaturewhere it was difficult to cool the watersufficiently before recycling back to thecaster.19 ALUMINIUM INTERNATIONAL TODAY JULY/AUGUST 2008 www.aluminiumtoday.com

CASTHOUSE1008099 99 9895 9791403033200220106040200Aluminum penetration in % of units** in terms of weightHeattransferfinstock**CylinderheadsHeattransfertubes3065Engineblocks5950Wheels2010017Bumperbeams143 3 5 1 4 1 4CrashboxesChassis** Body** EnginecradleSource: Hydro Aluminium; Ducker Research Co.; Knibb Gormezano & Partners20 KHvZ/BAT Chassis1 Distribution by market of use of aluminium in EuropeW Miller – Aleris2 Growing applications for aluminium in automobilesSource Hydro Al, Ducker Research & Knibb Gomezano & PartnersThe problem of graphite dust sprayedonto the caster rolls of strip casters as arelease agent was also brought up.Surprisingly, few casters are equippedwith extraction hoods which results indust from the evaporated suspension ofgraphite in water coating the surroundingplant. One solution presently underdevelopment is the use of talc powderinstead of graphite, although, as pointedout, this would simply replace black dustwith white. More importantly, littleconcern was expressed over the risk tooperating personnel ingesting thesepowders which can be sub 10 micronsize. It was concluded that work wasneeded in this area. On the question ofthe risk of Legionnaires bacteriumcontaminating the caster water circuit,this was not considered a hazard as thebacterium is killed at temperatures over60ºC, thus there was no need fordisinfecting treatments to the water aspracticed by a limited number of casthouses, for example in Australia.KEY NOTE PRESENTATIONSDay 2 opened with a presentation on theuse of aluminium in the transportindustry by Dr Bill Miller, ResearchDirector Aleris Europe. Refreshingly, DrMiller did not follow the ‘party line’ oftoo many of the Aluminium associationswhich demand the total replacement ofsteel by aluminium in all transportapplications with dubious arguments ofthe ‘green’ credentials of the metal arisingfrom energy savings in service and adubious claim of the ‘total’ ability torecycle aluminium which convenientlyignores the problems of mixed scrap,contamination, dross formation and thedisposal of fluxing salts. Instead, he drewon his knowledge from the workconducted by his former employer, steeland aluminium producer, Corus, (whicheventually sold its aluminium processingfacilities to Aleris), and the workundertaken by the steel community toreduce the weight of the ‘body in white’(BIW) by applying a range of high andultra-high strength steels. He acceptedthat there was a case for vehicles made of‘hybrid’ materials, with aluminium usedwhere most appropriate, for example toreduce the weight at the front of thevehicle to improve handling, but to usesteel for the remainder of the body to addstability to the rear of the vehicle andreduce costs in volume production.Looking at the distribution of the useof aluminium in the European market,transport holds the largest share(36%) (Fig 1).Karl-Heinze von Zengen, ProjectManager Aluminium Chassis, BentelerAutomotive also addressed the issue oflightweighting of automobiles on theclosing day of the conference.He reminded the audience that the first‘all aluminium’ car was developed in 1946when there was a shortage of steelfollowing WWII but a surplus ofaluminium as the demand for war planeshad slumped. The car, the Mathis VL333three-wheeler had a total weight of 386kgof which 78kg was the Aluminium BIW.Its 15hp 707cc engine achieved a fuelconsumption of 3litres per 100km. In theEU (15)the passenger car was by far themost popular mode of transport with10024 passenger km per person per yeartravelled by this mode beating by nearlyan order of magnitude that of the secondmost popular, bus and coach (1092) and802 by rail.Reducing weight is still one of the mosteffective means of reducing emissions(Table 1).Of mass produced cars, currently theAudi A4 and Mercedes C use the mostaluminium at about 200 and 210kgrespectively representing 15.5% of thetotal weight in the Audi and 12.5% in theMercedes. In a modern large sized massproduced passenger car weighing 1935kg(BMW 7 series), steel accounts for 45%by weight (864.6kg), light metals 22%(431.1kg) and thermoplastics 9.94%(192.3kg).The number of applications ofaluminium in automobiles is growingrapidly with roles requiring heat transferleading but with applications in bumperbeams and crash boxes and chassisapplications rising significantly (Fig 2).Mr von Zengen also addressed thevalue of material at end of life showingthat although a typical medium sized carmay contain only 125kg Al comparedwith 1100kg steel and 400kg of othermaterials the value of that recoverablealuminium was US$125 compared withthat for steel of $110.TURKISH ALUMINIUMAccording to Mr Bahadir, Vice PresidentAssan Alüminyum, per capitaconsumption of aluminium in TurkeyFactor Per Unit Saving(gCO 2/km)Weight (kg) 100 10.0Drag Coefficient 0.01C w3.2Rolling Resistance 0.1% 1.8Electrical Consumpt 1A 0.3Source: VolkswagenTable 1 Reduction of CO 2emissions from carsby various meanshas jumped significantly in recent yearsand now stands at over 7kg/capitacompared with 3-3.5kg in 2001-2. Thecountry is one of the fastest consumers ofaluminium in the world.He presented a profile of AssanAlüminyum saying that the companynow has two plants, one at Tuzla and theother at Dilovasi producing 125kt/y ofcontinuously cast aluminium strip.Indeed, the company operates some ofthe widest strip casters worldwide at2400mm. Expansion projects will bringthe number of casters up to 17 by 2012.Of total output, 50kt is rolled to foil.Turnover in 2007 was US$720M and thecompany employs 950. The company isthe largest aluminium producer inTurkey, is one of the top 50 companies inthe country and is ranked within the topseven producers in Europe. Exportsaccount for 60% of output. Since 1998, anaverage compound growth rate (CAGR)of 19% has been experienced (apart froma small dip in 2001). Growth is predictedto slow to 9.5% during the next five yearswith sales expected to reach 175kt thisyear and 250kt by 2011. A precoatingline and lacquering line are planned tobe added.The company has developedpartnerships in research, and with 20 ALUMINIUM INTERNATIONAL TODAY JULY/AUGUST 2008 www.aluminiumtoday.com

CASTHOUSEcustomers and with suppliers. It hasentered into an agreement with Pyrotekto develop ceramic components andimprove metal cleanliness.Murat Ozaydinli, President of Refsan,Turkey and Chairman of Pyrotek Turkeyreviewed the Turkish aluminiumindustry which was established in the1950s and now produces around550-600kt/y of bar, extrusions and flatsmainly for the construction, automotiveand kitchenware markets. Major exportmarkets are Germany, Italy, UK and Iraq.There are presently 19 continuouscasting strip lines in operation togetherproducing 225kt/y and 12 new lines are tobe commissioned during 2008-9 bringingtotal capacity of cast strip to 500kt/y.Output of extrusions is 250kt/y andcable 30kt/y. Capacity is expected to reach1Mt/y within the next few years.CASTHOUSEThe remainder of the presentationsfocussed on casthouse performance.Many of the descriptions were of triedand tested components and details ofthese will largely be found within thepages of Aluminium International Today assix bound-in supplements running everyother issue from September/October2005 to September/October 2007(available from Pyrotek).Consequently, this report willconcentrate on some of the more recentdevelopments and enhancements.Foremost of these is the developmentof a flexible glass fibre compositerefractory know as RFM (ReinforcedFibreglass Material). Sylvain Tremblay ofPyrotek Canada introduced the materialas being a robust, chemically inert tomolten aluminium material which issuitable for the manufacture of complexand thin walled shapes. Examples of itsapplications are numerous and includelaunder liners, skim dams, combo bagcradles, skimming baffles and controlpins for metal flow.The material is made by moulding asilica or calcium silicate based slurrycontaining coupling agents and nonwetting(to Al) agents around a glass fibreweave to produce a light, thin and strongshape which is resistant to cracking, has alow mass and thermal conductivity andexcellent resistance to corrosion bymolten aluminium. No preheating isrequired and the material is not wetted by3 RFM launder liner for a Properzi continuouscaster4 RFM skim dam for a DC ingot slab caster 5 RFM reusable ReMad cradle for a combo bagaluminium and so is easy to clean forreuse. Its properties contrast withtraditional refractories which are dense,fragile and have only a fair to goodresistance to corrosion by moltenaluminium and are limited in thecomplexity of shapes into which they canbe formed.The maximum operating temperatureof RFM is 1000ºC and the specificproperties can be modified dependingwhether fused silica or calcium silicate isused as the slurry constituent and by thetype and quantity of glass fibre present.Applications presented by SylvainTremblay include the lining of a steellaunder which delivers moltenaluminium to a Properzi continuouscaster which conventionally is protectedwith a ceramic ‘paper’ which was prone tobreak down after 8-12 hours use due tosuch factors as contamination by oil. Thisresults in inclusions in the cast barproduct which lead to failure duringsubsequent wire drawing. Replacing thepaper with a moulded RFM linerincreased casting time to 72-96 hours andthe liner was still reusable even after thisperiod (Fig 3). Use of the pre mouldedRFM also minimised set-up time.Another application was the skim damwhich may be necessary during ingot(slab) casting to prevent dross beingdrawn into the mould particularly whencasting alloys containing Mg. The skimdam (Fig 4) surrounds the combo bagwhich distributes the molten metal intothe mould, and floats on the surface ofthe metal. The RFM material is not onlyfar more robust than a conventional fusedsilica dam but also floats deeper in themetal thereby having a better ‘cuttingeffect’ in preventing dross passingbeneath the dam. A customer wasreported to have increased yield from96.6% to 99% when casting AA-5182 in acampaign of 17700t. In addition. The castsurface of the ingot is improved.Other applications for RFM in itsvarious forms were presented in laterpapers. These include the ReMad(Reusable Molten AluminiumDistributor) frame which supports asimplified rigid combo bag and improvesdistribution of metal in the mould sincethe bag remains rigid (Fig 5). Up to 50replacement combo bags have been usedin a single ReMad although the product isnormally supplied with 25. The RFMcontrol pin (Fig 6) is yet anotherapplication consisting of a hollow tube ofRFM material onto which a wearresistance ceramic sphere is attachedwhich controls the metal outflow as thecontrol pin is raised and lowered. Forsafety, a wire is attached to the stoppersphere which passes through the hollowstem to ensure that should a breakageoccur the sphere will remain attached tothe assembly and not be lost in the melt.The low thermal mass of this pin reducespre-heating times and also the number ofaborted casts due to chilling of the metal.On the billet casting table, RFMappears in the form of cross-feederdistributors (Fig 7) where it offers lowertemperature loss across the table due toits low thermal capacity and its lowershrinkage serves to keep joints tight.Indeed, cross distributors are now beingoffered in multiple blocks rather than assingles to minimise the joints which areprone to open up due to shrinkage ofconventional cross distributors. Alan Sale,Billet Casting process Manager ofPyrotek who presented this application –which is sold under the trade name ‘Titan’– explained how a hard shell has beendeveloped on the surface of the refractoryto resist erosion by the moltenaluminium but a more flexible insulatingcore has been maintained to reducethermal shock. An average 1% gain in pityield has been achieved through greaterproductivity, lower maintenance andlonger refractory life. Energy savingsworth $15000/y for a 56t furnace arepossible as less superheat is required.Two other products – not employingRFM, were described by Mark VincentProduct Development, Pyrotek. One wasthe auto heating launder which consistsof a section of launder into which areembedded heating elements (Fig 8). Thiscan maintain metal at a temperature of6 The control pin is made of an RFM tube ontowhich is attached a hard silica stopper22 ALUMINIUM INTERNATIONAL TODAY JULY/AUGUST 2008 www.aluminiumtoday.com

CASTHOUSERefining Alloy Oxide Grade Boride Grade Grain size (m)Standard 5/1 2.3 0.8 126Standard 5/0.2 1.3 0.2 155Standard 3/1 1.9 2.0 145Improved 3/1 2.7 0.8 127Table 2 Comparison of standard and improved 3/1 grain refining agent7 Cross feeder distributors in RFM reduce heatgradients across the caster table700ºC. Once heated, the launder must bekept hot and a lid is supplied to conserveheat. Energy requirements are 4kWh/mof launder.The second product described by MarkVincent was the Stable MetalTemperature Furnace (SMT) which isdesigned for continuous strip castinglines and can accommodate a flow rate ofup to 45kg/min. The aim is to eliminatethe thermal spikes experienced at changeover of the holding furnaces by buildingtwo ‘Sialon’ heating elements into an inlinefurnace with a capacity of 320kglocated prior to the caster head box. Acontrol system maintains the temperatureof the aluminium in the SMT within +/-1ºC of 703ºC (Fig 9).As well as Pyrotek personnel, noncompetitorsuppliers of equipment andconsumables presented papers.Franco Gramaglia, Marketing DirectorBruno Presezzi well known for itscontinuous bar casters described theirmove into continues strip caster in 2003in partnership with their customerProfilglass. A key difference between thePresezzi strip caster and establishedcasters is the effectiveness of cooling thecasting rolls. In both cases this is achievedby circulating water through channelsbetween the roll arbour and replaceableroll shell, but in the conventional casterthe channels are in the arbour whereas inthe Presezzi caster they are machined into the inner surface of the shell. Thisimproves the efficiency of cooling thecaster rolls as it increases the area ofcontact between the circulating coolingwater and the shell by 60%, although, MrGramaglia conceded, there has been noconsistent correlation between this andincreased productivity.David Salee of Wagstaff R&Ddescribed Wagstaff’s ‘Airslip’ mould forextrusion billet casting. In this processgas is blown through the porous graphitering along with the mould lubricant tocreate a gaseous emulsion between thesolidifying billet and the mould wall.This not only creates an improvedsurface finish on the billet but also animproved internal structure with ashallower columnar crystal chill zoneradiating from the surface, a narroweralloy denuded zone and a more uniformgrain size across the section. Anautomatic gas supply controller called‘AutoFlo’ is now available to replace themanual adjustment of gas flow rateswhich is required for each individualbillet mould. In trials, AutoFlo bringsgains in yield of 2.5% worth an estimated$200k a year plus more than a doublingof the graphite ring life from 300 to 628drops worth $14500 (for a 30 mouldtable), reduced table turn around timeworth $367k/y as well as reduced pitcleaning worth $120k/y and improvedrecovery worth $250k/y.Dr Angela Hardman of London &Scandinavian Metallurgical Co (LSM)described the mechanism of grainrefinement. Grain refiners are usuallyalloys of Al-Ti-B typically in ratios of Al-5%Ti-1%B (designated 5/1), Al-3%Ti-1%B (3/1) and Al-5%Ti-0.2%B (5/0.2)and occasionally Al-Ti-C. The 5/1 ismost commonly used in Europe. Grainrefiners work on the principal that TiB2particles that are below a critical radiuswill nucleate grains as the aluminiumsolidifies, but an excess of Ti must bepresent to restrict grain growth oncesolidification has started. However,since the Ti:B ratio affects cleanlinessthere is a desire to move toward thelower Ti 3/1 refiner. LSM havedeveloped an improved 3/1 refinerwhich consistently refines as effectivelyas 5/1 and more effectively thanconventional 3/1, although the oxidecontent is not improved over using 5/1(Table 2).Vedat Sancakdar of ASAS Alüminyum,Turkey reviewed the effect of extrusionparameters on the quality of anodising.ASAS Alüminyum operates its own casthouse of capacity 35kt/y, has threeextrusion presses of capacity 25kt/y andfour anodising baths of capacity 7.8kt/y. Italso has an electrostatic coating line andQualicoat certification.Precipitates in the surface of theextruded section have different electrochemicalpotentials and may becomevisible to the eye after etching prior toanodising, if large. The speed of extrusionand cooling rate influence whetherprecipitates form on the surface of theprofile and so must be carefullycontrolled, a high extrusion speed beingdetrimental.The meeting concluded with a largenumber of satisfied participants who hadenjoyed a variety of technicalpresentations, discussion groups and anexcellent social programme each eveningincluding a visit to an authentic Turkishrestaurant with entertainment and acruise on the Bosphorus.Plans were announced to hold the 5thMelt Quality Workshop in two to threeyears from 2008.8 Automatic launder heating system9 Layout of the Stable Metal Temperature (SMT) furnace for stripcasting MQW 4 : Istanbul, May 200824 ALUMINIUM INTERNATIONAL TODAY JULY/AUGUST 2008 www.aluminiumtoday.com