Material Science

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Author:
ereim
ID:
33827
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Material Science
Updated:
2010-09-13 10:35:34
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Chapter2 Properties Metals
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Chapter2 Properties of Metals
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  1. The process were a cold-worked metal is heated to or above the temperature at which metal atoms return to their equilibrium positions to increase the ductility of that metal
    Annealing
  2. The ability of a material to undergo little or no plastic deformation prior to fracture.
    Brittleness
  3. The reverse of tensile stress. Adjacent parts of the material tend to press against each other through a typical stress plane.
    Compressive stress
  4. The permanent deformation of a metal that increases with time under constant load or stress.
    Creep
  5. The ability of a material to deform easily upon the application of a tensile force, or as the ability of a material to withstand plastic deformation without rupture
    Ductility
  6. A transitory dimensional change that exists only while the initiating stress is applied and disappears immediately upon removal of the stress.
    Elastic strain
  7. The property of a material that enables it to resist plastic deformation, penetration, indentation, and scratching
    Hardness
  8. The ability of a metal to exhibit large deformation or plastic response when being subjected to compressive force
    Malleability
  9. A dimensional change that does not disappear when the initiating stress is removed
    Plastic deformation
  10. The state of stress just before plastic strain begins to appear and is defined by the stress level and the corresponding value of elastic strain.
    Proportional limit
  11. Exists when two parts of a material tend to slide across each other in any typical plane of shear upon application of force parallel to that plane
    Shear stress
  12. When a metal is subjected to a load (force), it is distorted or deformed, no matter how strong the metal or light the load.
    Strain
  13. The ability of a material to resist deformation. Usually considered based on the maximum load that can be borne before failure is apparent
    Strength
  14. The internal resistance, or counterforce, of a material to the distorting effects of an external force or load
    Stress
  15. Type of stress in which the two sections of material on either side of a stress plane tend to pull apart or elongate
    Tensile stress
  16. Describes how a material reacts under sudden impacts. It is defined as the work required to deform one cubic inch of metal until it fractures.
    Toughness
  17. The maximum resistance to fracture. It is equivalent to the maximum load that can be carried by one square inch of cross-sectional area when the load is applied as simple tension. It is expressed in pounds per square inch.
    Ultimate tensile strength
  18. Defined as the stress at which a predetermined amount of permanent deformation occurs.
    Yield strength
    • Tensile - Pulling apart
    • Compressive - from each end
    • Shear - pull parallel to the stress plane
    • Point 1 to 2 is the elastic curve where the material will still be able to return to its original state
    • After point 3 the material will hold its new shape
    • Point 4 is the point at which the material can no longer be stretch before it is cracked
    • Point 5 is the fracture point where the material will break

    This is a typical curve of a ductile material
  19. Iron and Water combine in a corrosion event to create hydrogen gas and Magnetite
  20. Zirconium reacts with water to create Zirconium Oxide and Hydrogen Gas
  21. STATE how iron crystalline lattice, γ and α, structure deforms under load
    It is easier for planes of atoms to slide by each other if those planes are closely packed. This allows more deformation.
  22. State Hooke's Law
    In the elastic range of a material, strain is proportional to stress.
  23. Define Young's Modulus
    (Elastic Modulus) as it relates to stress: Is the ratio of stress to strain (E)

    E=Stress/Strain
  24. Define Bulk Modulus and Fracture Point
    • Bulk Modulus - The elastic response to hydrostatic pressure and equilateral tension or the volumetric response to hydrostatic pressure and equilateral tension.
    • Fracture Point - The point where the material fractures due to plastic deformation
  25. Typical Brittle Material Stress Strain Curve
  26. Identify how slip effects the strength of a metal.
    An increase in slip will decrease the strength of a metal
  27. Describe the effects on material properties caused by
    Temperature
    Pressure
    Irradiation
    Cold and Hot Working
    • Temperature - An increase in temp, increases ductility
    • Pressure - Distortion may result from pressure stress
    • Irradiation - Increases in irradiation decrease ductility
    • Cold and Hot Working - Decreasing the grain size through cold or hot working of the metal tends to retard slip and thus increases the strength of the material
  28. Identify the reactor plant application for which high ductility is desirable
    Ductility is desirable for high-temp, high-pressure applications, Reactor Vessel. 574oF 2235psi
  29. State how heat treatment affects the properties of heat-treated steel and carbon-steel
    As hardness and tensile strength increase in heat treated steel, toughness and ductility decrease. (Cooling faster produces smaller grain sizes with harder metals)
  30. Describe the adverse effects of welding on metal including types of stress and methods for minimizing stress
    Welding can induce internal stresses that will remain in the material after welding is completed. Elongation occurs where residual compressive and tensile stresses develop. Welding stresses can be minimized by using heat sink welding, which results in lower metal temperatures and by annealing.
  31. Describe hydrogen embrittlement including the two required conditions and the formation process
    The process by which steel loses its ductility and strength due to tiny cracks that result from the internal pressure of hydrogen (H2) or methane gas (CH4) which forms at the grain boundaries. Sources include manufacture, welding, H2 as a by product of general corrosion.
  32. Identify why Zircaloy - 4 is less susceptible to hydrogen embrittlement than Zircaloy - 2
    Zircaloy - 4 contains less nickel

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