GOVERNMENT COLLEGE OF ENGINEERING, SALEM. CAST IRON PRESENTED BY JEEVA.TYASODHA.M.

GOVERNMENT COLLEGE OF GOVERNMENT COLLEGE OF ENGINEERING,ENGINEERING,

SALEM.SALEM.

CAST IRONCAST IRON

PRESENTED BYPRESENTED BY

JEEVA.TJEEVA.T

YASODHA.MYASODHA.M

INTRODUCTIONINTRODUCTION

  Cast iron usually refers to grey Cast iron usually refers to grey

iron, but also identifies a large iron, but also identifies a large group of ferrous alloys, which group of ferrous alloys, which solidify with a eutectic.solidify with a eutectic.

Cast iron tends to be brittle, Cast iron tends to be brittle, except for malleable cast irons.except for malleable cast irons.

The color of a fractured surface The color of a fractured surface can be used to identify an alloy.can be used to identify an alloy.

CONTENTSCONTENTSCAST IRON.CAST IRON.CLASSIFICATION.CLASSIFICATION.

WHITE.WHITE. MALLEABLE.MALLEABLE. GRAY.GRAY. DUCTILE.DUCTILE.

APPLICATIONS OF CAST IRONS.APPLICATIONS OF CAST IRONS.HEAT TREATING TO CONTROL HEAT TREATING TO CONTROL

STRUCTURE.STRUCTURE.

ABOUT CAST IRONABOUT CAST IRON

Family of ferrous alloys.Family of ferrous alloys.Cast into desired shape – not Cast into desired shape – not

worked.worked.2-4% C and 1-3% Si.2-4% C and 1-3% Si.Instability of Fe3C:Instability of Fe3C:Cementite / graphite flakes / Cementite / graphite flakes /

graphite nodules.graphite nodules.

TYPES OF CAST IRONTYPES OF CAST IRON

Alloying elements.Alloying elements.Grey cast iron.Grey cast iron.White cast iron.White cast iron.Malleable cast iron.Malleable cast iron.Ductile cast iron.Ductile cast iron.

CAST IRONCAST IRON

SCHEMATIC OF TYPES OF CAST SCHEMATIC OF TYPES OF CAST IRONSIRONS

PART 2 OF SCHEMATIC PART 2 OF SCHEMATIC

CLASSIFICATION OF CAST IRONCLASSIFICATION OF CAST IRON

S.NO TYPES OF CAST IRON

GRAPHITE DUCTILITY PROPERTY

1 WHITE NO NOFAST

COOLING RATES

2 GRAY Flake NOSLOW

COOLING RATES

3 MALLEABLEAnneal:flake tonodule

YESWHITE IRON + ANNEALING

HEAT TREATMENT

4 NODULAR Nodular YESADDITIONS MADE SO

THATNODULES OF

GRAPHITEFORM

INSTEAD OF FLAKES

FACTORS INFLUENCING WHICH FACTORS INFLUENCING WHICH WILL FORMWILL FORM

%C%C

%SI%SI

TEMPERATURE TEMPERATURE (COOLING RATE)(COOLING RATE)

COMPOSITION AND TYPE OF CAST COMPOSITION AND TYPE OF CAST IRONIRON

COOLING RATE AND TYPE OF CAST COOLING RATE AND TYPE OF CAST IRONIRON

GREY VS NODULAR CAST IRON GREY VS NODULAR CAST IRON (X250)(X250)

Gray – graphite as Nodular – graphite as Gray – graphite as Nodular – graphite as Flakes Flakes

nodules nodules

Brittle DuctileBrittle Ductile

FerriticFerritic

pearlitipearliticc

WHITE CAST IRONWHITE CAST IRON

Fe3 C+ pearlite. Fe3 C+ pearlite. Hard, brittle. Hard, brittle. Shows a “white” crystalline Shows a “white” crystalline fractured surface. fractured surface. Excellent wear resistance. Excellent wear resistance. High compressive stress.High compressive stress.

MALLEABLE CAST IRONMALLEABLE CAST IRON

White cast iron + annealing White cast iron + annealing treatment.treatment.

During annealing treatment During annealing treatment graphite nucleates and grows graphite nucleates and grows from the Fe3C to form nodules.from the Fe3C to form nodules.

GRAY CAST IRONGRAY CAST IRON

During slow solidification carbon During slow solidification carbon in Fe separates or graphitizes to in Fe separates or graphitizes to form separate graphite flakes.form separate graphite flakes.

DUCTILE/NODULAR CAST IRONDUCTILE/NODULAR CAST IRON

Mg added to molten iron.Mg added to molten iron.

Helps to spheroids graphite.Helps to spheroids graphite.

Low levels of minor elements Low levels of minor elements such as S and P.such as S and P.

GENERAL CHARACTERISTICS/ GENERAL CHARACTERISTICS/ ADVANTAGES OF GRAY CAST IRONADVANTAGES OF GRAY CAST IRON

Cheap.Cheap.Low melting point.Low melting point.Fluid – easy to cast, especially advantageous Fluid – easy to cast, especially advantageous

into large complex shapes.into large complex shapes.Excellent machine ability.Excellent machine ability.Excellent bearing properties.Excellent bearing properties.Excellent damping properties.Excellent damping properties.Excellent wear resistance (hi C).Excellent wear resistance (hi C).Can be heat treated (surface hardened etc.).Can be heat treated (surface hardened etc.).Can be alloyed etc.Can be alloyed etc.Essentially steel + graphite.Essentially steel + graphite.

GREAT AT DAMPENINGGREAT AT DAMPENING

Relative ability of ferrous metals to dampen Relative ability of ferrous metals to dampen vibrations. The energy absorbed per cycle, or vibrations. The energy absorbed per cycle, or specific damping capacity of these can differ by specific damping capacity of these can differ by more than 10 times.more than 10 times.

GRAY CAST IRON (EXAMPLE)GRAY CAST IRON (EXAMPLE)

3.0 %C.3.0 %C.graphite forms as flakes during graphite forms as flakes during

solidification.solidification.Have γ dendrites + eutectic γ + Have γ dendrites + eutectic γ +

graphite flakes at T < 1153°C.graphite flakes at T < 1153°C.99% γ + 1 % graphite flakes.99% γ + 1 % graphite flakes.

COMMENTS ON TENSILE COMMENTS ON TENSILE PROPERTIESPROPERTIES

Ferritic – softest; pearlitic – strongest.Ferritic – softest; pearlitic – strongest.Variation in elastic modulus.Variation in elastic modulus.0 ductility – tensile strengths only 0 ductility – tensile strengths only

quoted.quoted. C – 2.75-3.5%, Si 1.5-3.0%C – 2.75-3.5%, Si 1.5-3.0% Graphite flake types and size.Graphite flake types and size.

Fine uniform size wanted, get by:Fine uniform size wanted, get by: increased superheat to casting.increased superheat to casting. Inoculation with ferrosilicon or calcium Inoculation with ferrosilicon or calcium

silicon. silicon.

TENSILE PROPERTIESTENSILE PROPERTIES

APPLICATIONS OF DUCTILE CAST APPLICATIONS OF DUCTILE CAST IRONSIRONS

DUCTILE/NODULAR CAST IRONDUCTILE/NODULAR CAST IRON

Gray iron composition for C and Gray iron composition for C and Si.Si.

Impurity level control important Impurity level control important as it will affect nodule formation.as it will affect nodule formation.

Have nodule instead of flake if Have nodule instead of flake if we add in 0.05% Mg and/or Ce.we add in 0.05% Mg and/or Ce.

As cast structure: graphite forms As cast structure: graphite forms as nodules instead of flakes.as nodules instead of flakes.

NODULAR CAST IRONNODULAR CAST IRON

γ + graphite on cooling below A1 must γ + graphite on cooling below A1 must decide:decide: γ α + graphiteγ α + graphite γ α +Fe3Cγ α +Fe3C Favored by slow cooling rates, short Favored by slow cooling rates, short

diffusion paths etc.diffusion paths etc.γ first follows a) in regions surrounding γ first follows a) in regions surrounding

nodules.nodules.Carbon diffuses to existing nodules.Carbon diffuses to existing nodules.As T decreases and diffusion path increases As T decreases and diffusion path increases

remaining.remaining.γ α +Fe3C(pearlite).γ α +Fe3C(pearlite).

HEAT TREATMENT CONTROLHEAT TREATMENT CONTROL

If we want more ductility (less If we want more ductility (less strength) heat.strength) heat.

Treat to convert pearlitic areas to α Treat to convert pearlitic areas to α + graphite.+ graphite. Heat to 900°CHeat to 900°C Cool at 20°C/hr from 790° to 650°CFCool at 20°C/hr from 790° to 650°CF Normal furnace cooling.Normal furnace cooling. Could be done as one step with slower.Could be done as one step with slower.

Original cooling.Original cooling.

CONCLUSIONCONCLUSION

Finally we concluded that we are all Finally we concluded that we are all known about the “BASICS OF CAST known about the “BASICS OF CAST IRON” which is above in the paper.IRON” which is above in the paper.

THANK YOU…..THANK YOU…..