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Questions and Answers
The chemical composition of cast iron influences the appearance of carbon in the material.
The chemical composition of cast iron influences the appearance of carbon in the material.
True
Ductile cast iron contains primarily free carbon in the form of graphite.
Ductile cast iron contains primarily free carbon in the form of graphite.
False
The morphology and distribution of graphite are not factors in the classification of cast irons.
The morphology and distribution of graphite are not factors in the classification of cast irons.
False
Low cooling rates in cast iron production promote the formation of carbides.
Low cooling rates in cast iron production promote the formation of carbides.
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Grey cast iron is classified based on its fracture surface appearance.
Grey cast iron is classified based on its fracture surface appearance.
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Ductile cast iron features graphite in the form of squares.
Ductile cast iron features graphite in the form of squares.
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Ductile cast iron demonstrates significant improvement in mechanical properties compared to gray cast iron.
Ductile cast iron demonstrates significant improvement in mechanical properties compared to gray cast iron.
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Magnesium acts as a spheroidizer of graphite in ductile cast iron.
Magnesium acts as a spheroidizer of graphite in ductile cast iron.
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Ductile cast iron has worse fatigue resistance compared to steel.
Ductile cast iron has worse fatigue resistance compared to steel.
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Ductile cast iron has a higher melting point than steel.
Ductile cast iron has a higher melting point than steel.
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Austenite rejects carbon, which precipitates as iron carbide upon combining with the iron in the matrix.
Austenite rejects carbon, which precipitates as iron carbide upon combining with the iron in the matrix.
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The transformation from austenite to pearlite occurs upon heating.
The transformation from austenite to pearlite occurs upon heating.
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Austenitic grain boundaries do not influence the formation of secondary cementite.
Austenitic grain boundaries do not influence the formation of secondary cementite.
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Austenite adds carbon, which results in the formation of Fe3C.
Austenite adds carbon, which results in the formation of Fe3C.
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At room temperature, the composition consists of 100% pearlite and transformed ledeburite.
At room temperature, the composition consists of 100% pearlite and transformed ledeburite.
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Cooling of an ipoeutectic liquid results in the formation of primary cementite before lediburite.
Cooling of an ipoeutectic liquid results in the formation of primary cementite before lediburite.
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The role of silicon in alloys increases the amount of carbon in the eutectic.
The role of silicon in alloys increases the amount of carbon in the eutectic.
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Ledeburite is a mixture that forms during the cooling of an undercooled liquid metal.
Ledeburite is a mixture that forms during the cooling of an undercooled liquid metal.
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Metastable eutectics can be achieved with lower supercooling than stable eutectics.
Metastable eutectics can be achieved with lower supercooling than stable eutectics.
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The austenite to pearlite transformation is instantaneous at high temperatures.
The austenite to pearlite transformation is instantaneous at high temperatures.
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The carbon equivalent of a eutectic composition without silicon is 4.3%.
The carbon equivalent of a eutectic composition without silicon is 4.3%.
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Eutectic cast iron has a carbon content of 4.3%.
Eutectic cast iron has a carbon content of 4.3%.
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The Fe-Fe3C diagram illustrates the behavior of austenitic compositions only.
The Fe-Fe3C diagram illustrates the behavior of austenitic compositions only.
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Cementite and transformed ledeburite are 100% present at room temperature.
Cementite and transformed ledeburite are 100% present at room temperature.
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Silicon decreases the temperature of the stable eutectic formation.
Silicon decreases the temperature of the stable eutectic formation.
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Ledeburite consists of an austenite matrix with Fe3C globules.
Ledeburite consists of an austenite matrix with Fe3C globules.
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Austenite does not reject carbon during the cooling process.
Austenite does not reject carbon during the cooling process.
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Cooling of an ipereutectic composition alloy results in the formation of ledeburite.
Cooling of an ipereutectic composition alloy results in the formation of ledeburite.
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The addition of silicon causes the carbon content of the eutectic to increase.
The addition of silicon causes the carbon content of the eutectic to increase.
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The transformed ledeburite can consist of Martensite, Bainite, or Ferrite.
The transformed ledeburite can consist of Martensite, Bainite, or Ferrite.
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Cooling a liquid with the eutectic composition results in the formation of austenitic crystals.
Cooling a liquid with the eutectic composition results in the formation of austenitic crystals.
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The metastable Fe-Fe3C diagram illustrates the cooling of an ipoeutectic iron alloy.
The metastable Fe-Fe3C diagram illustrates the cooling of an ipoeutectic iron alloy.
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At room temperature, transformed ledeburite contains 100% austenite.
At room temperature, transformed ledeburite contains 100% austenite.
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The solidification of eutectic composition leads to a micostructure called Ledeburite.
The solidification of eutectic composition leads to a micostructure called Ledeburite.
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The pearlitic structure provides a lower ultimate tensile strength (UTS) compared to ferritic matrix cast irons.
The pearlitic structure provides a lower ultimate tensile strength (UTS) compared to ferritic matrix cast irons.
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Grey cast iron has poor thermal conductivity.
Grey cast iron has poor thermal conductivity.
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The designation 'GJ' in Grey Cast Iron refers to its cast iron symbol.
The designation 'GJ' in Grey Cast Iron refers to its cast iron symbol.
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Grey cast iron is used in applications such as machine tool bases and engine blocks.
Grey cast iron is used in applications such as machine tool bases and engine blocks.
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Graphite in grey cast iron acts as a solid lubricant, enhancing wear resistance.
Graphite in grey cast iron acts as a solid lubricant, enhancing wear resistance.
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Grey cast iron has excellent machinability.
Grey cast iron has excellent machinability.
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Grey cast iron is considered to be expensive compared to other materials.
Grey cast iron is considered to be expensive compared to other materials.
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The characteristic mechanical property in the designation of Grey Cast Iron is represented by the number 200.
The characteristic mechanical property in the designation of Grey Cast Iron is represented by the number 200.
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Study Notes
Cast Iron Classification
- Cast iron is classified into refining or first casting (80-85%) and foundry or second casting (15-20%).
- The first casting is used for steel production, while the second casting is used in foundries.
Cast Iron Characteristics
- Cast iron is an alloy of iron and carbon (2.01% to 4%) and often contains silicon (0.5% to 3%).
- Key characteristics include good machinability (excluding white cast iron), high fluidity, and low melting points.
- Cast iron is generally inexpensive.
Factors Affecting Carbon Appearance in Cast Iron
- Chemical composition
- Cooling rate
- Heat treatment
- Si and low cooling rates are graphitizing factors, hindering carbide formation.
Cast Iron Classification Based on Structure
- Cast iron classification is based on carbon combination (cementite or graphite) and morphology/distribution.
- Types include white cast iron, gray cast iron, ductile cast iron, and malleable cast iron.
Role of Silicon in Cast Iron
- Silicon reduces the amount of carbon in the eutectic and eutectoid.
- It increases the temperature of the stable eutectic (graphite).
Carbon Equivalent
- Carbon equivalent (CE) is calculated as %C + %Si/3.
- Higher CE values promote graphite formation.
Role of Chromium in Cast Iron
- Chromium makes solidification more likely according to the metastable Fe-Fe3C system.
- This leads to anti-graphitizing effect.
Grey Cast Iron
- Graphite is in the form of flakes.
- Good castability and low shrinkage.
- Good thermal conductivity.
- Good machinability, vibration damping, and wear resistance.
- Inexpensive.
White Cast Iron
- Has cementite (hard and brittle).
- Reflective fracture surfaces.
- High hardness (≥50 HRC) and wear resistance.
- Produced with relatively low carbon and silicon content, high cooling rates, and thin sections.
- Used in rolling mill cylinders, grinding balls, and facing plates.
Ductile Cast Iron
- Graphite is in the form of spheroids.
- Significant improvement in all mechanical properties (ductility).
- Good resistance to fatigue and wear.
- Lower-melting material than steel with comparable mechanical characteristics.
- More common material after gray cast iron and steel.
Malleable Cast Iron
- Obtained from white cast irons through heat treatment.
- Graphite nodules are formed from the transformation of cementite.
- Good combination of resistance and ductility.
Alloy Cast Irons
- They have alloying elements capable of increasing various properties, including corrosion resistance, high temperature strength, oxidation resistance, and abrasive wear resistance.
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Description
This quiz covers the classification and characteristics of cast iron, including its composition and the factors affecting carbon appearance. It also explores the role of silicon in cast iron and the different types based on structure. Test your knowledge on this essential material used in various industries.
