Material Science and Machining Processes Quiz
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Questions and Answers

What is the slope of the stress-strain diagram from O to P known as?

  • Yield Strength
  • Ultimate Strength
  • Modulus of Elasticity (correct)
  • Modulus of Toughness

    • The yield point indicates the maximum stress a material can withstand before rupture.

    False

    What is the region in the stress-strain diagram from point O to P called?

    elastic range

    The ______ strength is defined as the maximum strength of the material at rupture.

    <p>rupture</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Proportional Limit = Stress is directly proportional to strain Elastic Limit = Material no longer returns to original shape Yield Point = Significant elongation without load increase Ultimate Strength = Maximum tensile strength of the material</p> Signup and view all the answers

    Which of the following processes is NOT part of bulk processes?

    <p>Stamping</p> Signup and view all the answers

    Sheet metalworking is characterized by high surface area to volume ratio.

    <p>True</p> Signup and view all the answers

    Name one type of operation that can be classified as machining.

    <p>Turning</p> Signup and view all the answers

    The property of a material that allows it to return to its original size and shape after a load stops acting on it is called __________.

    <p>elasticity</p> Signup and view all the answers

    Match the following fabrication methods with their descriptions:

    <p>Welding = Joining parts using heat Brazing = Joining with a filler metal above melting point Bolting = Joining parts with mechanical fasteners Adhesives = Joining using chemical bonding agents</p> Signup and view all the answers

    Which machining method uses a wheel composed of abrasive particles?

    <p>Grinding</p> Signup and view all the answers

    Ductility refers to a material's ability to fracture under stress.

    <p>False</p> Signup and view all the answers

    What is the role of hardening processes in machining?

    <p>To increase the material's shear strength and make it more difficult to cut.</p> Signup and view all the answers

    Which of the following is an example of step-reaction polymerization?

    <p>PET</p> Signup and view all the answers

    High-density polyethylene (HDPE) has a high degree of branching compared to low-density polyethylene (LDPE).

    <p>False</p> Signup and view all the answers

    What is a copolymer?

    <p>A copolymer is made by linking two different types of monomers in the same polymer chain.</p> Signup and view all the answers

    A polymer is considered polar if it has __________ and __________ poles.

    <p>positive, negative</p> Signup and view all the answers

    Match the type of polymer with its description:

    <p>Homopolymer = Made from one type of monomer Copolymers = Involves two different types of monomers Terpolymer = Composed of three different types of monomers LDPE = Has a highly branched structure</p> Signup and view all the answers

    Which factor does NOT affect the polarity of a polymer?

    <p>Color</p> Signup and view all the answers

    Low-density polyethylene (LDPE) has a higher melting point than high-density polyethylene (HDPE).

    <p>False</p> Signup and view all the answers

    What is the purpose of copolymerization?

    <p>To combine properties of different monomers to enhance and improve the properties of the final product.</p> Signup and view all the answers

    What is a common property of zinc?

    <p>It is bluish white in color.</p> Signup and view all the answers

    Lead can be easily cut with a knife.

    <p>True</p> Signup and view all the answers

    What is the melting point of zinc?

    <p>420°C</p> Signup and view all the answers

    Lead has a boiling point of __________.

    <p>1600°C</p> Signup and view all the answers

    Match the following uses of zinc and lead with their appropriate applications.

    <p>Zinc = Making roofing sheets Lead = Used for making gas pipes</p> Signup and view all the answers

    Which of the following methods is used for creating small intricate parts such as jewelry and machine components?

    <p>Casting</p> Signup and view all the answers

    Expendable mold casting allows the mold to be reused multiple times.

    <p>False</p> Signup and view all the answers

    What is the elastic limit in the context of the stress-strain diagram?

    <p>The point beyond which a material no longer returns to its original shape</p> Signup and view all the answers

    The yield point is the maximum stress that a material can endure before it fractures.

    <p>False</p> Signup and view all the answers

    What is the primary characteristic of Powdered Metallurgy?

    <p>It can keep tight tolerances and often requires no secondary fabrications.</p> Signup and view all the answers

    In metal forming, raw metal is usually manipulated in __________ form.

    <p>sheet metal</p> Signup and view all the answers

    What does Young's Modulus represent in a stress-strain diagram?

    <p>The constant of proportionality between stress and strain in the elastic range.</p> Signup and view all the answers

    Match the following metal manufacturing processes with their appropriate description:

    <p>Casting = Involves melting and molding metal Powder Processing = Uses pressure and heat to form shapes from powdered metal Cold Working = Subjects metal to mechanical stress for permanent structure change Forming = Mechanically manipulates raw metal into desired shapes</p> Signup and view all the answers

    The region in a stress-strain diagram where permanent deformation occurs is called the __________ range.

    <p>plastic</p> Signup and view all the answers

    Match the following terms with their corresponding definitions:

    <p>Proportional Limit = The stress value where stress is directly proportional to strain Ultimate Strength = The maximum stress a material can withstand before failure Rapture Strength = The strength of a material at the point of rupture Yield Point = The point where noticeable deformation occurs without an increase in load</p> Signup and view all the answers

    Which process is NOT suitable for high-strength applications?

    <p>Powder Processing</p> Signup and view all the answers

    Deformation processes involve applying stresses that exceed the yield strength of metal.

    <p>True</p> Signup and view all the answers

    What is the main advantage of metal forming compared to casting?

    <p>Higher strength, ductility, and workability.</p> Signup and view all the answers

    What defines tensile strength in materials?

    <p>Ability to withstand deformation under tensile loading without breaking.</p> Signup and view all the answers

    Compressive stress results in an increase in the material's length.

    <p>False</p> Signup and view all the answers

    What is the term used to describe the ratio of change in length to the original length in materials?

    <p>simple strain</p> Signup and view all the answers

    The stress that results from forces applied parallel to the resisting area is known as __________.

    <p>shearing stress</p> Signup and view all the answers

    Which type of material is characterized by having relatively large tensile strains before rupture?

    <p>Ductile materials</p> Signup and view all the answers

    Brittle materials can experience relatively large strains before reaching their point of rupture.

    <p>False</p> Signup and view all the answers

    What is the typical unit of measure used for stress in materials?

    <p>psi, N/mm2 or Mpa</p> Signup and view all the answers

    Which of the following is a characteristic of and the reason for the formation of intermediate phases in alloys?

    <p>They form when the dissolving element exceeds the solid solubility limit of the base metal.</p> Signup and view all the answers

    Ferrous metals do not contain iron as a primary constituent.

    <p>False</p> Signup and view all the answers

    What is the carbon content range for Grey Cast Iron?

    <p>About 3%</p> Signup and view all the answers

    Metals generally exhibit good __________ conductivity, making them ideal for electrical applications.

    <p>electrical</p> Signup and view all the answers

    Match the type of cast iron with its property:

    <p>Grey Cast Iron = Fractures to show a grey appearance White Cast Iron = Fractures to show a silver-white luster Chilled Cast Iron = Contains about 3.3% carbon</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Cast Iron?

    <p>It can be tempered.</p> Signup and view all the answers

    What are the three classifications of Ferrous metals?

    <p>Cast iron, wrought iron, and steel</p> Signup and view all the answers

    Non-ferrous metals contain significant amounts of iron.

    <p>False</p> Signup and view all the answers

    Which of the following polymers are examples of step-reaction polymerization?

    <p>PET</p> Signup and view all the answers

    High-density polyethylene (HDPE) is a result of highly branched molecular chains.

    <p>False</p> Signup and view all the answers

    What type of polymer is created by linking only one type of monomer?

    <p>Homopolymer</p> Signup and view all the answers

    Polymers can be classified based on their branching degree, with _______ indicating higher density due to closely packed molecules.

    <p>HDPE</p> Signup and view all the answers

    Match the following types of polymers with their definitions:

    <p>Homopolymer = Linked by one type of monomer Copolymer = Linked by two different types of monomers Terpolymer = Linked by three different types of monomers</p> Signup and view all the answers

    Polarity in materials influences properties like melting point and solubility.

    <p>True</p> Signup and view all the answers

    What type of stress results from a tensile force applied to a material?

    <p>Tensile stress</p> Signup and view all the answers

    Which crystal system has atoms arranged at the corners of the cube with another atom at the center?

    <p>Body-Centered Cubic (BCC)</p> Signup and view all the answers

    In a Face-Centered Cubic (FCC) structure, there are 2 atoms in one unit cell.

    <p>False</p> Signup and view all the answers

    Brittle materials can undergo large strains before breaking.

    <p>False</p> Signup and view all the answers

    What is the packing density of the Simple Cubic (SC) structure?

    <p>relatively low</p> Signup and view all the answers

    What is the term used for the ratio of change in length to the original length in materials?

    <p>Strain</p> Signup and view all the answers

    The property of __________ describes how atoms are arranged within a unit cell.

    <p>centering</p> Signup and view all the answers

    Which of the following describes a ductile material?

    <p>It has large tensile strains up to rupture.</p> Signup and view all the answers

    Match the following metallic crystal structures with their characteristic:

    <p>Simple Cubic (SC) = Each corner is occupied with one atom Body-Centered Cubic (BCC) = Atoms touch along cube diagonals Face-Centered Cubic (FCC) = Atoms touch along face diagonals</p> Signup and view all the answers

    Which of the following is a characteristic of the arrangement in a Face-Centered Cubic (FCC) structure?

    <p>Atoms are located at the corners and face centers</p> Signup and view all the answers

    Which term refers to the internal stress caused by compressive forces?

    <p>Bearing stress</p> Signup and view all the answers

    Polonium is an example of a metal that forms a Simple Cubic (SC) structure.

    <p>True</p> Signup and view all the answers

    Normal stress can be classified as either tensile stress or compressive stress.

    <p>True</p> Signup and view all the answers

    How many types of crystal systems can be defined based on length and orientation?

    <p>7</p> Signup and view all the answers

    What defines a unit cell in the context of crystal structure?

    <p>A tiny block formed by atomic arrangements</p> Signup and view all the answers

    Lattice parameters are represented by only three dimensions.

    <p>False</p> Signup and view all the answers

    Name two areas of science that focus on the study of materials.

    <p>Engineering Materials, Material Science</p> Signup and view all the answers

    The arrangement of atoms in crystalline solids affects their __________.

    <p>properties</p> Signup and view all the answers

    Which statement about crystalline solids is true?

    <p>Their properties depend on the crystal structure.</p> Signup and view all the answers

    Gold was the first metal to be used by mankind.

    <p>True</p> Signup and view all the answers

    What are the six lattice parameters in crystal structures?

    <p>a, b, c, α, β, γ</p> Signup and view all the answers

    Which of the following metals is NOT an example of a body-centered cubic (BCC) structure?

    <p>Zinc</p> Signup and view all the answers

    The hexagonal closed-pack (HCP) structure contains 6 atoms per unit cell.

    <p>True</p> Signup and view all the answers

    What notation is used to represent crystallographic directions?

    <p>[xyz]</p> Signup and view all the answers

    The two lattice parameters of the hexagonal closed-pack (HCP) structure are 'a' and __________.

    <p>c</p> Signup and view all the answers

    Match the following crystal structures with their examples:

    <p>Body-Centered Cubic (BCC) = Iron Face-Centered Cubic (FCC) = Aluminum Hexagonal Closed-Pack (HCP) = Zinc Simple Cubic (SC) = Polonium</p> Signup and view all the answers

    Which equation represents the relationship between the cube edge length 'a' and the atomic radius 'R'?

    <p>a = 2R</p> Signup and view all the answers

    A line or vector in crystallography is termed a 'crystallographic coordinate'.

    <p>False</p> Signup and view all the answers

    Describe how to convert crystallographic directions from four notation to three notation in hexagonal crystals.

    <p>Use the equations: x = (2X - Y) / 3, y = (2Y - X) / 3, u = -(x + y) and z = Z.</p> Signup and view all the answers

    What is the primary reason for extracting carbon from cast iron to produce Malleable Cast Iron?

    <p>To increase its ductility</p> Signup and view all the answers

    Wrought Iron has a carbon content of 2.0%.

    <p>False</p> Signup and view all the answers

    What are two types of cast iron mentioned in the content?

    <p>Malleable Cast Iron and Toughened Cast Iron</p> Signup and view all the answers

    ______ iron is an almost pure form of iron with high resistance to corrosion.

    <p>Wrought</p> Signup and view all the answers

    Match the following types of steel with their carbon content:

    <p>Low Carbon Steel = Up to 0.3% Medium Carbon Steel = 0.3% to 0.6% High Carbon Steel = 0.6% to 2.0%</p> Signup and view all the answers

    What is the coordination number for Face-Centered Cubic (FCC) and Hexagonal Close-Packed (HCP) structures?

    <p>12</p> Signup and view all the answers

    The Atomic Packing Factor (APF) for Simple Cubic (SC) structures is 0.68.

    <p>False</p> Signup and view all the answers

    What is the primary purpose of alloying metals?

    <p>To enhance properties such as strength and hardness.</p> Signup and view all the answers

    The _____ density refers to the number of atoms per unit length along a specific direction.

    <p>linear</p> Signup and view all the answers

    What type of solid solution involves solvent atoms being replaced by dissolved elements?

    <p>Substitutional Solid Solution</p> Signup and view all the answers

    Match the following with their definitions:

    <p>Coordination Number = Number of nearest neighbor atoms Atomic Packing Factor = Volume of atoms divided by volume of unit cell Planar Density = Density of atomic packing on a particular plane Linear Density = Number of atoms per unit length along a direction</p> Signup and view all the answers

    All metals have a non-crystalline structure.

    <p>False</p> Signup and view all the answers

    What are the two classifications of alloys?

    <p>Solid solution and intermediate phase.</p> Signup and view all the answers

    Study Notes

    Introduction to Engineering Materials

    • Engineering materials are crucial for survival and daily life.
    • Gold was the first metal used, followed by copper.
    • Areas of science focusing on materials include Engineering Materials, Material Science, and Materials Engineering.

    Basic Concepts of Crystal Structure

    • Properties of crystalline solids depend on the crystal structure.
    • The manner in which atoms, ions, or molecules are spatially arranged influences these properties.
    • A space lattice or lattice is a periodic arrangement of points in space.
    • A lattice point represents each atom.
    • A lattice array is the arrangement of lattice points.
    • Lattice space is the space covered by lattice points.
    • A unit cell is a tiny block formed by arrangements of small groups of atoms.
    • It represents the symmetry of the crystal structure.
    • The unit cell can be defined as a small repeat entity, the basic structural unit, or the building block of the crystal structure.
    • Lattice parameters (a, b, c, α, β, γ) describe the dimensions and angles of the unit cell.
    • These parameters are typically on the order of a few Angstroms (Å) or 0.1 nanometers.
    • The orientation and equality of these parameters define the 7 crystal systems (cubic, hexagonal, tetragonal, rhombohedral, orthorhombic, monoclinic, and triclinic).

    Bravais Lattices

    • There are 14 types of crystal systems.
    • These systems include properties of centering.
    • Types of centering include Face-Centered, Body-Centered, and Base-Centered.

    Metallic Crystal Structures

    • Simple Cubic (SC):
      • Three mutually perpendicular axes pass through one corner of the unit cell.
      • Each corner is occupied by one atom.
      • Polonium is the only element that has this structure.
      • Packing density is relatively low.
    • Body-Centered Cubic (BCC):
      • Atoms are arranged at the corners of the cube, with an additional atom at the center.
      • Examples include alpha iron, chromium, tungsten, tantalum, and molybdenum.
    • Face-Centered Cubic (FCC):
      • Atoms are arranged at the corners and centers of each face of the unit cell.
      • Atoms are assumed to touch along face diagonals.
      • Examples include aluminum, copper, gold, lead, silver, and nickel.

    Hexagonal Closed-Pack (HCP)

    • The unit cell is formed with top and bottom planes of 7 atoms, and a half-hexagon in between.
    • Two lattice parameters (a and c) define the basal and height parameters.
    • Six atoms are present in one unit cell.
    • Zinc, lithium, magnesium, and beryllium are examples.

    Crystallographic Directions

    • Directions in a crystal are represented by the coordinates (x, y, z) of a vector passing through the origin.
    • Notation: [uvw].
    • Conversion between four-notation and three-notation systems is explained for hexagonal crystals.

    Properties of Crystals:

    • Coordination Number: The number of nearest neighbor atoms or ions surrounding an atom or ion.
    • Atomic Packing Factor (APF or Packing Efficiency): Ratio of volume of atoms in a unit cell to volume of unit cell.
      • SC: ~ 0.52
      • FCC and HCP: ~ 0.74
      • BCC: ~ 0.68
    • Planar Density: Density of atomic packing on a particular plane.
    • Linear Density: Number of atoms per unit length along a particular direction.

    Metals

    • Employed in various engineering purposes and requirements.
    • Iron is the most popular metal in engineering.
    • All metals have a crystalline structure.

    Alloys

    • Alloys are mixtures or compounds of two or more elements, at least one of which is metallic.
    • Alloying enhances properties such as strength and hardness.
    • Alloys can be classified as solid solutions or intermediate phases.
    • Substitutional Solid Solution: atoms of a solvent element are replaced in its unit cell by atoms of a dissolved element.
    • Interstitial Solid Solution: atoms of a dissolved element fit into vacant spaces between base metal atoms in the lattice structure.
    • Intermediate Phases: have limits to solubility of one element in another. They have intermediate chemical composition and different crystalline structures.

    Importance of Metals

    • High stiffness and strength (can be alloyed for high rigidity)
    • Hardness (capacity to absorb energy better than other materials)
    • Good electrical conductivity
    • Good thermal conductivity
    • Cost (steel is competitive with other engineering materials)

    Metals Used in Manufacturing Process

    • Cast Metal: Starting form is a casting.
    • Wrought Metal: Metal that has been worked or can be worked after casting.
    • Powdered Metal: Starting form is small powders for conversion into parts using powder metallurgy techniques.

    Classification of Metals

    • Ferrous Metals: Contain iron as the main constituent. Classified as cast iron, wrought iron, and steel.
    • Non-ferrous Metals: Practically do not contain iron.

    Cast Iron (C.I)

    • Carbon content ranges from 2 to 4.23%.
    • Formed by melting pig iron with coke and lime stone.
    • Types of Cast Iron include:
      • Gray Cast Iron: 3% carbon content, soft, melts easily used in cylinders, pistons
      • White Cast Iron: 2.0-2.5% carbon content, hard, unworkable in machines.
      • Chilled Cast Iron: 3.3% carbon content, hard on the surface, soft inside, used in rail car wheels, dies, sprockets
      • Malleable Cast Iron: 2.3% carbon content, malleable
      • Toughened Cast Iron: cast iron obtained by melting cast iron with wrought iron scrap.

    Wrought Iron

    • Almost pure iron (0.15% carbon).
    • Manufacturing stages include refining, puddling, shingling, and rolling.
    • Properties: soft at white stage, ductile, malleable, tough, 1500°C melting point, and resistant to corrosion.

    Steel

    • Iron alloy with up to 2.0% carbon.
    • Types of steel include low carbon (mild), medium carbon, and high carbon steel.

    Alloy Steel

    • Steel to which other elements are added to obtain special properties.
    • Examples include chromium steel, cobalt steel, manganese steel, tungsten steel, vanadium steel, and nickel steel.

    Polymers

    • Polymers are engineering materials of very high molecular weight.
    • Created by joining monomer units.
    • Used in food packaging, clothing, home furnishing, transportation, medical devices, and other applications.
    • Types of Polymerization include:
      • Chain-reaction: monomers bond to form polymers.
      • Step-reaction: monomers bond through release of small molecules.

    Polymer Structure and Properties

    • Crystallinity: High ordered structure (crystalline) verses random structure (amorphous).
    • Molecular Weight Distribution: Wider distribution easier to melt, narrower distribution harder to melt.
    • Viscoelasticity: Exhibits both viscous (flow) and elastic (return to original shape) properties.

    Nanomaterials

    • Nanotechnology is the science, engineering, and technology conducted at the nanoscale (1-100 nanometers).
    • Nanomaterials are nano-scale particles, tubes, rods, or fibers. They have wide range in applications (health, electronics, cosmetics, textiles, information technology and environmental protection).
    • Manufacturing methods:
      • Top-down: reducing large pieces of material to nanoscale.
      • Bottom-up: building up from atomic- and molecular-scale components.
    • New processes:
      • Chemical vapor deposition
      • Molecular beam epitaxy
      • Atomic layer epitaxy
      • Nanoimprint lithography
      • Roll-to-roll processing
      • Self-assembly
    • Potential effects: Include potential interactions with biological systems (e.g. brain diseases) and potential environmental impacts.

    Mechanical Properties of Materials

    • Strength: Capacity of material to withstand breaking, bowing, or deformation.
    • Elasticity: Ability of a material to return to its original shape and size after stress is removed.
    • Plasticity: Ability to deform permanently without fracture.
    • Ductility: Ability to deform and draw into wires.
    • Tensile Strength: Ability to deform without fracture when pulled or stretched.
    • Stress: Strength of a material per unit area.
    • Normal Stress: Tensile or compressive stress.
    • Shearing Stress: Force applied parallel to the resisting area.
    • Bearing Stress: Contact pressure between bodies.
    • Simple Strain: Ratio of change in length to original length.
    • Stress-Strain Diagram: Graphical representation of stress and strain relationship.

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    Test your knowledge on material science concepts and machining processes. This quiz covers the stress-strain diagram, types of strength, and machining methods. Additionally, you'll explore key properties of materials and fabrication techniques essential in engineering.

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