ductile iron foundary practice


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  • DUCTILE IRON FOUNDARY PRACTICEMMSE 24 seminar5th MAY, 2016Department of Mechanical Engineering, M S RAMAIAH INSTITUTE OF TECHNOLOGY, BENGALURU-560054, Karnataka, IndiaRAJKUMAR S WAGMARE 1MS15MSE10


  • contentsIntroduction Melting practiceDesulfurization methodsComposition controlMagnesium treatmentInoculation , Casting and solidificationEngineering propertiesAustempered Ductile iron(ADI)Applications ConclusionReferences

  • Introduction Foundries produce castings that are close to the final product shape, i.e., near-net shape components.Castings are produced by pouring molten metal into moulds , with cores used to create hollow internal sections. After the metal has cooled sufficiently, the casting is separated from the mould and undergoes cleaning and finishing techniques as appropriate.Molten metal is prepared in a variety of furnaces, the choice of which is determined by the quality,quantity and throughput required

  • Spheroidal graphite cast iron, also referred to as ductile ironThese spheroids are obtained directly during solidification of castings and no by any heat treatmentDuctile iron is a family of cast graphitic irons which possess high strength ductility and resistance to shock. Annealed cast ductile iron can be bent, twisted or deformed without fracturing. Its strength, toughness and ductility


  • Introduction Ductile iron crankshaftDuctile iron automotivesteering knuckle

  • DESULPHURIZATIONIntroducing magnesium it is necessary to bring the sulphur atleast upto 0.03%is to remove all the sulphur possible for best spheroidizing resultHigher sulphur content will also result in increase of the consumption of magnesium alloys

    For successful desulphurization, the following basic factors are desirable in the processes.a) Intimate contact between molten metals and the Desulphurizing agentb) Reaction durationc) Simple removal of sulphur bearing slags after desulphurizationd) Temperature controle) Fume controlf) Minimum refractory maintenanceg) Ease of handling and feeding of de-sulphurizing agent

  • Cont.Methods of desulphurization

    Reducing slag in furnace the metal can be effectively desulphurizedOne of the oldest and simplest methods of desulphurization is the addition of soda ash to the molten metal when poured into the ladle

    Fusite method- sodium carbonate is added from 0.5-1% by wt of molten metalCo2 and Na2O Combines with sulphur form a complex compound which comes as a slag to the top of the ladle which can be remobed

  • CONTFlour spur(CaF2) method-flourspar is added to MM in ladle which reacts with sulphur and forms ahighly basic slag which settles on top of the MMCalcium carbide methodCalcium carbide can be injected in the powder form along a carrier gas like nitrogrn into moletn metalIt reacts withsulphur to form calcium sulphide which goes as a slag

  • Composition control in DISulphur content of CI low as possible below 0.01%Carbon-3.2% to 4%, Si-1.8% to 3%,Manganese-0.25-0.5% Phosphorus-0.08 max, Sulphur-0.015%Residual magnesium-0.03 to 0.07%Carbon equivalent upto 4.6






  • INOCULATIONInoculation is the addition of small quantities of materials to molten metal iron which will bring about remarkable enhanced properties in the iron without appreciable changing the composition of the ironInoculants are silicon based inoculants Include ferrosilicate ,silicon carbide,cal-silcide,graphite etcInoculation alters the solidification processIncreases the degree of nucleation of the ironPrevents chill formation and undesirable graphite formWhy foundaries use inoculantsTo improve machinabilityTo ensure that castings meet customer requirements

  • INOCULATION OF DUCTILE & GREY IRONThe main purpose of inoculation is to achieve best mechanical properties and optimum machinability characteristics by:

    1. Control of graphite structure.2. Elimination or reduction of chill/carbide.3. Reduction of casting section sensitivityDUCTILE INOCULATION Optimum nodule shape Degree of nodularity Improves nodule count Prevention of formation of carbides Increases ferrite content.

  • Austempered Ductile Iron (ADI)Austempered ductile iron is obtained by heat treating the ductile iron in salt bath of sodium chloride, potassium chloride and barium chloride at the temperature of 830C. It was austempered at 350 - 420oC and later salt bath using sodium nitrate and potassium nitrate.ADI nominally has the chemical composition Fe, 3.6 C, 2.50 Si, 0.5 Mn, 0.032 Mg, 0.05S, 0.114 P wt.%,

  • Austempered Ductile Iron (ADI)Austempered Ductile Iron (ADI) is a ferrous, cast material with a high strength-to-weight ratio and good dynamic properties.The application of the Austempering process to ductile iron produces a material called Austempered Ductile Iron (ADI) that has a strength-to-weight ratio that exceeds that of aluminum.ADI Exihibites a microstructure consisting of graphite nodules like bainitic matrixPesence of bainitic in the matrix gives

    Increased toughnessGood wear resistanceFatique and impact strength to the materialVibration damping ability

  • APPLICATIONSADI is used in many branches of industry as machinebuilding, civil engineering, transport, military industry, mining etc. It is applied mainly to casting for dynamically loaded components, e.g. gear and traversing wheels, crankshafts of cars, vans and trucks, swivel pins, rail brakes, pressure pipes in oil industry etc.

  • References

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