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RAJKUMAR S WAGMARE
sem. M.Tech MSE
M.S.RAMAIAH INSTITUTE OF TECHNOLOGY
(AUTONOMOUS INSTITUTE,AFFILIATED TO VTU)
“DUCTILE IRON FOUNDARY PRACTICE”
MMSE 24 seminar5th
Department of Mechanical Engineering, M S RAMAIAH INSTITUTE OF TECHNOLOGY,
BENGALURU-560054, Karnataka, India
RAJKUMAR S WAGMARE
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
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
Ductile iron crankshaft
Ductile iron automotive
Introducing magnesium it is necessary to bring the sulphur atleast upto 0.03%
is to remove all the sulphur possible for best spheroidizing result
Higher 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
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
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
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%,
Residual magnesium-0.03 to 0.07%
Carbon equivalent upto 4.6
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 form
Why 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
Optimum nodule shape
Degree of nodularity
Improves nodule count
Prevention of formation of carbides
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
Good wear resistance
Fatique and impact strength to the material
Vibration damping ability
ADIis use d in m any branche s o f industry as
m achine building , civile ng ine e ring , transpo rt,‐
m ilitary industry, m ining e tc.
It is applie d m ainly to casting fo r dynam ically
lo ade d co m po ne nts, e . g . g e ar and trave rsing
whe e ls, crankshafts o f cars, vans and trucks,
swive lpins, railbrake s, pre ssure pipe s in o il
industry e tc.