MEC 147N Lecture 2: Ferrous Metal Alloys

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Questions and Answers

What is the main constituent of ferrous metal alloys?

Iron (correct)

Carbon

Copper

Aluminum

Which type of steel is characterized by containing less than about 0.25 wt% carbon?

Low-Carbon Steel (correct)

Alloy Steel

Medium-Carbon Steel

High-Carbon Steel

What characteristic defines ductility in a material?

Its ability to withstand high temperatures

Its ability to remain unchanged under stress

Its ability to resist scratching

Its ability to deform plastically before rupture (correct)

Which of the following best describes the hardness of a material?

Resistance to localized plastic deformation Signup and view all the answers

Low-carbon steels are known for their outstanding:

Ductility and toughness Signup and view all the answers

Which of the following applications is typical for low-carbon steels?

Automobile body components Signup and view all the answers

What is one limitation of low-carbon steels regarding heat treatment?

They do not respond to treatments forming martensite Signup and view all the answers

What is the yield strength of typical low-carbon steels?

275 MPa Signup and view all the answers

How is the strength of a material defined?

Its ability to resist externally applied forces Signup and view all the answers

Which organization has established codes referred to as AISI?

American Iron and Steel Institute Signup and view all the answers

What do the first two digits of the AISI/SAE designation for steel indicate?

The alloy content Signup and view all the answers

Which type of steel is represented by the designation 1060?

Plain carbon steel Signup and view all the answers

What is a characteristic of high-strength, low-alloy (HSLA) steels?

Resistant to corrosion Signup and view all the answers

Which element is NOT commonly added to medium-carbon steels to enhance their properties?

Tin Signup and view all the answers

What is the typical carbon concentration range for high-carbon steels?

0.60 to 1.4 wt% Signup and view all the answers

Which of the following applications is most likely a use for medium-carbon steels?

Machinery parts Signup and view all the answers

What effect does heat treatment typically have on low-carbon steels?

Increases tensile strength Signup and view all the answers

Which alloying element would NOT typically be found in tool and die steels?

Nickel Signup and view all the answers

What is the main characteristic of high-carbon steels compared to other carbon steels?

They are the hardest but least ductile Signup and view all the answers

Which type of steel typically has higher strength and corrosion resistance than plain low-carbon steels?

High-strength, low-alloy steels Signup and view all the answers

What is the primary alloying element in stainless steels that is essential for their corrosion resistance?

Chromium Signup and view all the answers

Which characteristic of gray cast iron allows it to effectively damp vibrational energy?

Graphite flakes structure Signup and view all the answers

What is a common fabrication method for cast iron due to its material properties?

Casting Signup and view all the answers

What is the typical carbon content range for gray cast irons?

2.5 - 4.0 wt% Signup and view all the answers

Which class of stainless steel is characterized by having a martensitic microstructure?

Martensitic Signup and view all the answers

What effect does slowly cooling gray cast iron have during manufacturing?

Forms graphite flakes Signup and view all the answers

What addition to gray cast iron produces ductile or nodular iron?

Magnesium Signup and view all the answers

What is the minimum chromium content required in stainless steel for effective corrosion resistance?

11 wt% Signup and view all the answers

What is the primary reason for using high-strength wire made from certain steels?

Hardness and wear-resistance Signup and view all the answers

Which of the following best describes the fluidity of gray cast iron in its molten state?

High fluidity Signup and view all the answers

What type of cast iron is formed when graphite appears as nodules or spherelike particles instead of flakes?

Ductile Cast Iron Signup and view all the answers

Which of the following is an advantage of ductile cast iron?

High ductility Signup and view all the answers

What is the primary feature of white cast iron?

It is formed with cementite (Fe3C). Signup and view all the answers

Malleable cast iron is primarily produced from which type of cast iron?

White Cast Iron Signup and view all the answers

Which of the following is NOT an application of malleable cast iron?

Rail car brake shoes Signup and view all the answers

The presence of graphite in the microstructure of ductile cast iron contributes to which property?

High impact resistance Signup and view all the answers

In which manufacturing process is white cast iron typically formed?

Rapid cooling Signup and view all the answers

What is the main benefit of using malleable cast iron in construction?

It offers improved ductility and resilience. Signup and view all the answers

Which component is generally not associated with the applications of ductile cast iron?

Railroad track materials Signup and view all the answers

What type of iron features a microstructure characterized by spherical graphite particles?

Ductile Iron Signup and view all the answers

Study Notes

Properties and Testing of Electromechanical Materials

Course: MEC 147N
Lecture: 2
Topic: Ferrous Metal Alloys
Presenter: Dr. Mohamed M. AbdelKader Hassan

Types of Metal Alloys

Ferrous alloys: Primarily composed of iron
Non-ferrous alloys: Not based on iron
Alloy Types within Ferrous:
- Steels (including low alloy, medium carbon, high carbon, high strength low alloy, plain, heat treatable, tool, stainless)
- Cast irons (including gray, ductile(nodular), white, malleable)

A- Steels Alloys (Low Alloys)

Steels are iron-carbon alloys, potentially with other alloying elements
Mechanical properties are affected by carbon content (typically <1.0 wt%)
Steels are classified into low-, medium-, and high-carbon types based on carbon concentration

Important Definitions

Strength: Resistance of a material to external forces without breaking or yielding.
Ductility: Ability of a material to be permanently deformed before rupture.
Hardness: Resistance of a material to localized plastic deformation (e.g., scratching or indentation)

i- Low-Carbon Steels

These steels contain less than 0.25 wt% carbon
Strengthened by cold working
Soft, weak, but exhibit high ductility and toughness
Machinable and weldable
Least expensive to produce
Used in automobile body components, structural shapes (I-beams, channels, angle iron) and sheets used in pipelines, buildings, bridges, and tin cans
Typical yield strength: 275 MPa
Typical tensile strength: 415-550 MPa
Typical ductility: 25%EL

ii- Medium-Carbon Steels

Carbon content between 0.25 and 0.60 wt%
Can be heat treated to improve mechanical properties
Stronger than low-carbon steels but less ductile and tough
Used in railway wheels, tracks, gears, crankshafts, and other machine parts

iii- High-Carbon Steels

Carbon content between 0.60 and 1.4 wt%
Hardest, strongest, and least ductile of the carbon steels
Commonly used for tool and die steels (containing chromium, vanadium, tungsten, and molybdenum)
Resulting in very hard and wear-resistant carbide compounds
Applications in cutting tools, dies, knives, razors, hacksaw blades, springs, and high strength wire

II – High Alloys (Stainless Steels)

Highly resistant to corrosion (rusting), especially in ambient atmospheres
Primarily contain chromium (at least 11 wt%)
Corrosion resistance can be enhanced with nickel and molybdenum
Classified as martensitic, ferritic, or austenitic based on microstructure
Versatile due to wide range of mechanical properties and corrosion resistance

B- Cast Irons

Ferrous alloys with carbon contents above 2.14 wt%
Typically contain 3.0-4.5 wt% carbon and other alloying elements
Very brittle
Casting is common fabrication method

i- Gray Cast Iron

Carbon content between 2.5 and 4.0 wt%
Graphite exists as flakes
Fractured surface has a gray appearance
Good damping properties and high fluidity at casting temperature
Used for pump housings, engine heads, and sanitary pipes

ii- Ductile (or Nodular) Iron

Similar to gray iron, but graphite exists as nodules rather than flakes
High ductility and machinability
Used in connecting rods and brake calipers

iii- White Cast Iron

Rapid cooling during manufacturing prevents graphite formation
Composed of cementite (Fe3C)
Very hard and wear-resistant
Used in mining shovels and rail car brake shoes

iv- Malleable Cast Iron

Intermediate product produced from white iron
Graphite exists as rosettes, increasing malleability
Used in transmission gears, differential cases, and pipe fittings

Comparison of Cast Iron

Includes micrographs comparing the four types of cast iron: Gray, Ductile, White, and Malleable

Characteristics of Non-ferrous Materials

Presents a table of characteristics including melting temperature, density, elastic modulus, typical strength, and applications for various non-ferrous metals.

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Description

Explore the properties and testing of ferrous metal alloys in this lecture from MEC 147N. Learn about the various types of ferrous alloys, focusing on steels and cast irons, along with important mechanical properties and definitions. This quiz will test your understanding of these concepts and their applications.