Ballast chapter 38-metals

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Ballast chapter 38-metals
2014-07-16 04:36:50
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are ballast chapter 38-metals review
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  1. what is smelting
    the process of refining the ore to extract the pure material
  2. what is fabrication
    the process of forming and shaping refined metal into the desired condition
  3. types of metal fabriciation
    casting, rolling (hot or cold) cold increases the metals strength, extruding (pushed), drawing (pulled)

    bending, break forming, spinning, embossing, annealing (metal is reheated and slowly cooled for more ductile metal), quenching (heating then rapidly cooling), tempering (sim to quenching but is not rapidly cooled), case hardening (produces a hard surface over a softer core)
  4. ways to finish metals
    mechanical, chemical, coatings
  5. ways to join metals
    fastners, welding, brazing (high temp using a filler metal-above 800deg), soldering (low temperature using a filler metal-below 500deg), adhesives
  6. galvanic action
    corrosion when 2 dissimilar  metals come into contact with eachother in the presense of and electrolyte (moisture)
  7. electrolysis
    a process with a mild electric  current is set up between 2 dissimiliar metals and corrosion occurs.
  8. what is a ferrous metal
    a metal that contains a substantial  amount of iron. (iron, steel, stainless steel and other special steel alloys)
  9. wrought iron
    wrought iron has a low carbon content. because of its low carbon content it is soft, ductile and resistant to corrosion. used mainly for ornamental iron work.
  10. cast iron
    has a carbon content above 2 percent. it is hard but brittle. used in columns and beams.

    white (low silicon content) and grey (high silicon content) cast iron. grey cast iron is used for plumbing valves, pipes and hardware
  11. disadvantages of steel
    • reduction in strength when subjected to fire
    • tendency to corrode in the presence of moisture
  12. ferrous materials will rust and corrode if not protected T/F
  13. what is bonderized
    to coat the material with an anticorrosive phosphate solution in preperation for the application of paint, enamel or lacquer
  14. as carbon is added to steel the ___________ increases and the ___________decreases.
    strength, ductility
  15. ways to treat steel to alter the physical properties
    • quenching and tempering
    • annealing (heating the metal and slowly cooling)
    • case hardening (process for heating a metal and diffusing a gas or liquid into its surface)
  16. stainless steel is composed of
    steel and chromium and nickel (to increase the corrosion resistance)
  17. what is passivity
    in reference to stainless steel it is when the choromium-oxide film layer does not allow metal ions at the surface to migrate into the solution. stainless steel can become active if it exposed to chemicals or it is exposed to abrasion.
  18. what the primary disadvantage of aluminum
    the amount of energy required for its refining and manufacture
  19. properties of copper
    • 1. resistance to corrosion
    • 2. workability
    • 3. high electrical conductivity
  20. what is an alloy
    a metal that combines two or more metals
  21. what is the alloy of bronze
    copper and tin
  22. what is the alloy of brass
    copper and zinc
  23. what is terneplate
    an alloy of 75%lead, 25%tin and is used to plate steel
  24. are brass and bronze are brazed or welded
    brazed (above 800deg)

    brass can be welded but is most often brazed