Cast Iron Properties Quiz and Flashcards

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Questions and Answers

What is the reason for the poor weldability of cast irons?

Formation of graphite-containing corrosion products

High carbon content and presence of silicon and manganese (correct)

Control of microstructure and properties

High ratio of performance to cost

What is the primary advantage of using cast irons in industrial applications?

Resistance to corrosion and wear

High ratio of performance to cost (correct)

High strength and toughness

High machinability and weldability

What is the effect of graphite flakes on the mechanical properties of gray cast iron?

Acts as stress raisers and initiates fracture (correct)

Improves toughness and elasticity

Reduces corrosion rates and wear

Increases machinability and ductility

What is the primary reason for the phasing out of cast iron pipes in the water industry?

Corrosion and deterioration over time Signup and view all the answers

What is the main benefit of the formation of graphite-containing corrosion products in buried cast iron pipes?

Decreases corrosion rates and wear Signup and view all the answers

What is the primary factor that determines the strength of gray cast iron?

The matrix in which the graphite flakes are embedded Signup and view all the answers

What is the purpose of adding magnesium or cerium to the ladle or molds in ductile cast iron production?

To promote the precipitation of graphite as spherical particles Signup and view all the answers

What is the typical microstructure of white cast iron?

Cementite and pearlite Signup and view all the answers

Why is spheroidal graphite CI widely used in crankshafts?

Because of its high strength and toughness Signup and view all the answers

What is the effect of annealing on spheroidal graphite CI?

It forms a ferritic matrix Signup and view all the answers

What is the primary reason why cast iron is commonly used for structures?

Because of its excellent compressive strength Signup and view all the answers

What is the primary purpose of controlling the mode and concentration of carbon in cast iron?

To produce various grades of CI with different mechanical properties Signup and view all the answers

What is a characteristic of cast iron that makes it inherently resistant to oxidation and corrosion?

Its high silicon content Signup and view all the answers

What is the main difference between gray cast iron and ductile cast iron?

The metallurgical structure of the two types of cast iron Signup and view all the answers

What is the advantage of using alloyed irons in comparison to regular cast iron?

They have enhanced resistance to heat, oxidation, and corrosion Signup and view all the answers

What is the primary reason why white cast iron is considered un-weldable?

The absence of ductility in the base metal and heat affected zone Signup and view all the answers

What is the primary advantage of malleable cast iron over ductile cast iron?

Improved machinability Signup and view all the answers

What is the primary benefit of compacted graphite cast iron over gray cast iron?

Improved strength and toughness Signup and view all the answers

What is the effect of adding chromium to chilled cast iron?

Increased hardness and improved abrasion resistance Signup and view all the answers

What is the primary difference between malleable cast iron and ferritic malleable cast iron?

Microstructure composition Signup and view all the answers

What is the primary function of chromium in alloyed cast iron?

To control chill depth and increase hardness Signup and view all the answers

What is the primary difference between corrosion-resistant and elevated-temperature service alloyed cast iron?

Their ability to resist corrosion in different environments Signup and view all the answers

What is the effect of high zinc content on the properties of brass?

Increased strength and ductility Signup and view all the answers

What is the primary advantage of using brass in musical instruments?

Its bright, gold-looking appearance and workability Signup and view all the answers

What is the primary difference between bronze and brass?

The presence of tin in bronze and zinc in brass Signup and view all the answers

What is the primary reason why bronze is used in marine and fishing applications?

High resistance to corrosion from saltwater Signup and view all the answers

Which of the following alloys is commonly used in soldering electronic components?

Solder (Lead-Tin) Signup and view all the answers

What is the primary advantage of using ceramic bearings over steel bearings?

Reduced weight Signup and view all the answers

Which of the following alloys is known for its excellent casting properties?

Aluminum-Silicon Signup and view all the answers

What is the primary role of zinc in galvanized steel?

To improve the corrosion resistance of the steel Signup and view all the answers

What is a characteristic of polymer bearings that makes them suitable for applications where traditional metal bearings may fail?

Self-lubrication Signup and view all the answers

What is the primary advantage of using bronze bearings in machinery and equipment?

Self-lubricating properties Signup and view all the answers

What is the primary cause of season cracking in certain materials?

Tensile stress in the presence of a corrosive environment Signup and view all the answers

What is the purpose of precipitation hardening in certain alloys?

To strengthen the alloy through the formation of precipitates Signup and view all the answers

What is the result of rapid cooling in the precipitation hardening process?

Dissolution of alloying elements Signup and view all the answers

What is the effect of precipitates on dislocation movement in precipitation-hardened alloys?

Decrease dislocation movement Signup and view all the answers

What is the primary application of precipitation-hardened alloys?

All of the above Signup and view all the answers

What is the primary method of preventing season cracking in materials?

All of the above Signup and view all the answers

What is the primary characteristic of polymer bearings that makes them suitable for applications where corrosion is a concern?

High corrosion resistance Signup and view all the answers

What is the primary difference between polymer bearings and traditional metal bearings?

Lubrication requirements Signup and view all the answers

Study Notes

Cast Irons

Composition: primarily iron (Fe), carbon (C), and silicon (Si), with traces of sulfur (S), manganese (Mn), and phosphorus (P)
Characteristics: brittle, non-malleable, relatively weak in tension, but excellent compressive strength
Classification: 5 groups based on composition and metallurgical structure:
- Gray cast iron
- Ductile cast iron
- White cast iron
- Malleable cast iron
- Compacted graphite iron
- Alloy cast iron

Gray Cast Iron

Composition: 2.5% to 4% carbon, 1% to 3% silicon
Characteristics: oldest and most common form of cast iron, brittle, good machinability, good damping characteristics
Properties: poor toughness, high ratio of performance to cost, ideal for production of shrinkage-free, intricate castings
Applications: engine blocks, valve bodies, machine tool housings, brake drums

Ductile Cast Iron (Spheroidal Graphite Iron)

Composition: similar to gray cast iron, but with addition of magnesium or cerium
Characteristics: higher strength and toughness, spherical graphite particles
Properties: excellent toughness, widely used in crankshafts, pearlitic matrix
Applications: water and sewer pipes, agricultural and automotive parts, electrical fittings, mining machinery

White Cast Iron

Composition: less than 4.3% carbon, low silicon content
Characteristics: hard, brittle, abrasion-resistant, light appearance
Properties: un-weldable, used in applications where abrasion resistance is important
Applications: liners for cement mixers, ball mills, drawing dies, extrusion nozzles

Malleable Cast Iron

Composition: heat-treated white cast iron
Characteristics: intermediate strength, toughness, and machinability between gray and ductile cast iron
Properties: ideal for applications where toughness and machinability are required
Applications: small castings, thin-section castings, automotive and agricultural parts, industrial casters

Compacted Graphite Iron

Composition: between gray and nodular graphite cast iron
Characteristics: useful combination of strength, thermal conductivity, and other properties
Properties: production requires controls similar to those for ductile iron castings
Applications: not specified

Chilled Cast Iron

Composition: localized area of cast iron cooled rapidly from the melt
Characteristics: carbides formed, hardness increases with carbon content
Properties: used in applications where high wear resistance is desirable
Applications: crushing of rocks and minerals

Alloyed Cast Iron

Composition: corrosion-resistant and elevated-temperature service alloys
Characteristics: classified into two types, with high chromium content for high wear resistance
Properties: used in applications where high wear resistance is desirable
Applications: chemical processing plants, petroleum refining, food handling, and marine service

Brass

Composition: primarily copper and zinc, with other metals added
Characteristics: malleable, high corrosion resistance, low melting point
Properties: high thermal conductivity, non-ferromagnetic, susceptible to cracking
Applications: decorative applications, musical instruments, plumbing pipes, electronic applications

Bronze

Composition: primarily copper and 12% tin, with other elements added
Characteristics: hardness, brittleness, high corrosion resistance, low metal-to-metal friction
Properties: used in functional and aesthetic applications
Applications: marine and fishing, sculptures, musical instruments, electrical connectors, bushings, and bearings

Aluminum Alloys

Duralumin (Aluminum-Copper): strong, lightweight, used in aircraft construction, automotive components
Aluminum-Lithium Alloys: high strength-to-weight ratio, used in aerospace applications
Aluminum-Silicon Alloys: excellent casting properties, used in automotive engine components

Lead Alloys

Solder (Lead-Tin): low melting point, good electrical conductivity, used in electronic components
Lead-Antimony Alloys: used in lead-acid batteries for vehicles and UPS
Lead-Calcium Alloys: used in maintenance-free lead-acid batteries

Tin Alloys

Bronze (Copper-Tin): used in art, sculpture, musical instruments, bearings
Pewter (Tin-Alloyed with Copper, Antimony, or Bismuth): used in decorative items, jewelry, small sculptures
Babbitt Metal (Tin-Antimony-Copper): low-friction alloy, used in bearings### Zinc Alloys
Zamak alloys are used in die-casting applications for producing complex shapes with excellent surface finish, making them suitable for automotive parts, electronic housings, and consumer goods.
Brass alloys have a wide range of applications including plumbing fixtures, musical instruments, decorative hardware, and electrical connectors due to their malleability, corrosion resistance, and attractive golden color.
Galvanized Steel is used in construction, automotive manufacturing, and household appliances to protect steel from corrosion.

Bearing Materials

High-carbon chromium bearing steel is commonly used for bearing applications due to its high hardness, wear resistance, and ability to withstand heavy loads and high temperatures.
Ceramic bearings are made from materials like silicon nitride (Si3N4) or zirconia (ZrO2) and offer advantages such as high hardness, corrosion resistance, and reduced weight.
Polymer bearings are made from materials like polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK) and offer advantages such as low friction, corrosion resistance, and self-lubrication.
Bronze bearings are used in applications where self-lubricating properties are required, such as in machinery and equipment.

Season Cracking

Season cracking, also known as stress corrosion cracking (SCC), is a phenomenon where a material fails prematurely under stress in the presence of a specific environment.
It occurs due to the combined effects of tensile stress and a corrosive environment, leading to the initiation and propagation of cracks in the material.
Materials susceptible to season cracking include certain alloys of brass, aluminum, stainless steel, and high-strength steels.
Preventing season cracking involves selecting materials resistant to the specific environment, controlling stress levels through proper design and manufacturing processes, and implementing corrosion control measures.

Precipitation Hardening

Precipitation hardening is a heat treatment process used to strengthen certain alloys, typically aluminum, stainless steel, or some nickel-based alloys.
The process involves heating the material to a specific temperature to dissolve alloying elements into a solid solution, followed by rapid cooling and then aging at a lower temperature to allow precipitates to form within the material.
The precipitates act as obstacles to dislocation movement, effectively increasing the strength and hardness of the alloy.
Precipitation hardening allows for the production of materials with a combination of high strength, toughness, and corrosion resistance, making them suitable for aerospace components, structural parts, and high-performance applications.

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This quiz covers the composition and properties of cast iron, including its carbon content, brittleness, and weakness in tension.

Cast Iron Properties

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