Presented by:RAJKUMAR S WAGMARE

1MS15MS101st sem. M.Tech MSE

M.S.RAMAIAH INSTITUTE OF TECHNOLOGY BANGALORE (AUTONOMOUS INSTITUTE,AFFILIATED TO VTU)

“DUCTILE IRON FOUNDARY PRACTICE”

MMSE 24 seminar5th MAY, 2016

Department of Mechanical Engineering, M S RAMAIAH INSTITUTE OF TECHNOLOGY, BENGALURU-560054, Karnataka, India

RAJKUMAR S WAGMARE 1MS15MSE10

contents Introduction Melting practice Desulfurization methods Composition control Magnesium treatment Inoculation , Casting and solidification Engineering properties Austempered Ductile iron(ADI) Applications Conclusion References

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 iron These spheroids are obtained directly during solidification of castings and

no by any heat treatment Ductile 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

DUCTILE IRON

Introduction

Ductile iron crankshaft

Ductile iron automotivesteering knuckle

DESULPHURIZATION

Introducing 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 agent

b) Reaction duration

c) Simple removal of sulphur bearing slags after desulphurization

d) Temperature control

e) Fume control

f) Minimum refractory maintenance

g) Ease of handling and feeding of de-sulphurizing agent

Cont…. Methods of desulphurization Reducing slag in furnace the metal can be effectively desulphurized One 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 metal Co2 and Na2O Combines with sulphur form a complex compound which

comes as a slag to the top of the ladle which can be remobed

CONT…

Flour 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 MM Calcium carbide method Calcium carbide can be injected in the powder form along a carrier gas

like nitrogrn into moletn metal It reacts withsulphur to form calcium sulphide which goes as a slag

Composition control in DI Sulphur 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

MAGNESIUM TREATMENT

SANDWICH METHOD

PLUNGING METHOD

T-NOCK METHOD

INJECTION PROCESS

INOCULATION Inoculation 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 iron

Inoculants are silicon based inoculants Include ferrosilicate ,silicon carbide,cal-silcide,graphite etc Inoculation alters the solidification process Increases the degree of nucleation of the iron Prevents chill formation and undesirable graphite formWhy foundaries use inoculants To improve machinability To ensure that castings meet customer requirements

INOCULATION OF DUCTILE & GREY IRON

The 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 sensitivity DUCTILE 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 matrix Pesence of bainitic in the matrix gives Increased toughness Good wear resistance Fatique and impact strength to the material Vibration damping ability

APPLICATIONS ADI is used in many branches of industry as

machine‐building, 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