Student exam questions - 2002
1. Corrosive:
a. describes a corrodable material
b. describes a substance which will corrode other substances - correct
c. used to describe stainless steels
d. orange in color
2. Cr Carbide particles form at grain boundary:
a. anodizing
b. sensitization - correct
c. segregation
d. galvanizing
3. Element that cannot be a sacrificial anode:
a. Zn
b. Mg
c. C
d. Pt
e. none of the above - correct.... no.....a sacrificial anode is one that dissolves to protect another metallic material. Zn and Mg can act as sacrificial anodes; the others cannot.
4. Pt:
a. very active (not inert) material
b. releases metallic ions when used as sacrificial anode in a tank
c. gives off C02 gas when used as sacrificial anode in a tank
d. none of the above - correct
5. Passivated:
a. SS without Cr2O3 film
b. SS with Al2O3 film
c. SS that attracts O
d. SS that occludes electrolytes, oxygen - correct
6. To defeat sensitization:
a. increase C content
b. weld the material
c. use a SS containing Ti or Nb - correct
d. none of the above
7. Characteristic of Cor-Ten steel:
a. do not contain Cu
b. Fe2O3 layer - correct
c. will never corrode
d. none of the above
8. In many Cr plate coatings:
a. Cu layer primarily provides corrosion resistance
b. Ni layer solely provides strength
c. Cu layer acts as the leveler - correct
d. matte Nickel layer gives rise to shine
9. Area effect:
a. Large cathode and small anode slow corrosion
b. try to keep potential anodic areas large relative to cathode - correct
c. small cathode and large anode accelerate corrosion
d. use of Cu current ?? keeps cell current density low
10. 6061 T6 Al alloy:
a. upon quenching Alss, Mg2Si particles precipitate
b. dislocation movement is increased by Mg2Si particles
c. precipitation hardening due to extremely large Mg2Si precipitates
d. ageing at about 160 degrees C strengthens the material - correct
11. Welding Cr-Mo steels:
a. produces soft HAZ and weld bead regions
b. is more difficult than welding Ti
c. causes a highly stressed, fine, strong pearlitic-bainitic type structure to form - correct
d. the HAZ and weld bead regions transform to pro-eutectoid ferrite and pearlite
12. He or Ar:
a. Used in conventional arc welding for oxidation protection
b. used to ignite a flame in MIG welding
c. used to prevent oxidation in TIG welding only
d. used to protect metal from oxidation in TIG and MIG welding. - correct
13. Titanium changes crystal structure at:
a) 0 degrees C
b) 55 degrees C
c) 882 degrees C (correct)
d) -100 degrees C
14. Which is true?
a) A substance which is corrosive will corrode other substances. *correct*
b) A substance that is corrodable will corrode other substances.
c) Stainless steels are noncorrosive, therefore it is always non-corrodable.
d) All of the above.
15. The four things necessary for a galvanic cell are:
A. Anode, cathode, noble metal, electrolyte
B. Electrical connection, anode, passivated surface, non-passivated surface
C. Cathode, anode, electrical connection, electrolyte <---------(correct)
D. Diode, cathode, electrical connection, electrolyte
16. Which type of alloy is most likely to be used in electrical contact springs?
a. Al-Cu
b. Al-Mg
c. Al-Ti
d. Cu-Be (correct)
e. Ti-V
17. After piercing a hot metal billet using a mandrel, the tube:
a) becomes soft due to the forming of dislocations in the material
b) has good dimensional accuracy due to the plastic flow at high temperatures
c) is annealed to loosen up dislocations and then cold worked
d) is cold drawn to gain good dimensional accuracy correct
18. When choosing a metal for an application such as a bike:
a) try to get a high yield/density ratio so you can maintain good strength and cut down on the weight of the product correct
b) try to minimize the yield/density ratio to cut down on the amount of material being used to maintain a required strength.
c) choose the one that is most dense since it will have the highest yield strength.
d) pick a metal such as titanium to minimize cost.
19. In the Al Mg phase diagram, quenching from the Alss region, and then ageing would cause:
a) a the material to become very weak since you are ageing and removing dislocations.
b) the Alss to be locked in permanently as a single phase
c) the precipitation of Mg2Si particles which inhibit dislocation motion.correct
d) a 2-phase alloy to be present without any precipitates
20. When dislocation motion is hindered by 2nd phase particles:
a) yield strength increases as particle strength decreases
b) yield strength increases as particle spacing increases
c) yield strength decreases as particle strength increases
d) yield strength increases as particle size increases correct
21. Looping of dislocations:
a) is easiest if there is a group of particles the dislocations can move around
b) speeds up the movement of the dislocations
c) causes the dislocation to become smaller as it loops
d) ultimately slows down the dislocation movement correct
22. The hardness of a material is greatest when:
a) the precipitate particles are tiny, close and able to be sheared
b) the precipitate particles are large in size and far apart
c) only looping or only shearing occurs for dislocation movement
d) the particles are a medium size and shearing and looping occurs by dislocations correct
23. At 882 degrees C, Ti :
a) changes its crystal structure to a bcp structure.
b) changes its structure to ccp like that of austenitic steels.
c) becomes an _ Ti solid solution
d) becomes a _ Ti solid solution
no correct answer
24. Ti and Ti alloys:
a) lack good resistance to corrosion
b) are a sponge for oxygen, nitrogen at moderately low temperatures
c) a very economical way to go when producing a product
d) can virtually be destroyed if held at a high temperature for a long period. correct
25. In MIG welding:
a) He or argon is used to protect the weld from oxidation correct
b) He and oxygen are used to clean the weld surface
c) He and nitrogen are used to create more of an arc
d) He and argon are used to keep a steady arc
26. When welding low hardenability steels:
a) a high cooling rate will yield a coarse P structure and proeutectoid Fe.
b) a low cooling rate will yield a MAR structure
c) a fine P structure in proeutectoid Fe can form in the HAZ region correct
d) a low cooling rate will yield an extremely fine P structure in Fe
27. Welding high hardenability steels:
a) can allow MAR to form correct
b) cannot form martensite without a severe quench
c) is virtually impossible to do
d) cannot form MAR in either the welded region because austenitizing
is not accomplished
28. Welding a plain carbon steel tube frame:
a) would ultimately strengthen the welded region and the HAZ region
b) relieves dislocations in the weld region correct
c) should not alter the material in any way
d) act as a tempering action causing precipitates
29. When welding a Cr-Mo steel frame:
a) a very large particle P forms in the weld and HAZ regions
b) a very weak P structure forms in the weld and HAZ regions
c) FE and P form in the HAZ region
d) a very fine, stressed, bainitic structure forms in the HAZ and welded regions correct
30. When welding a 6061-T6 frame:
a) the HAZ and welded regions have the highest hardness numbers
b) overageing causes a very hard material to be formed
c) a large amount of precipitates form closer to the welded region.
d) the welded region cools more rapidly and becomes soft.
31. Braze:
a) used in heat treating a material
b) a very hard metal, comparable to martensite
c) used at low temps to join metals together
d) a metallic glue correct
32. It would be wise to:
a) use brazing extensively on low carbon steels
b) use brazing on low C steels to further strengthen them
c) use brazing on a Cr Mo steel since strengthening comes from more cold
working
d) use brazing on a steel that has been strengthened by P and alloy carbides correct
33. Epoxy resin:
a) is cured at very high temperatures
b) is very ductile
c) is brittle correct
d) none of the above
34. Corrosion:
a) cannot occur for dissimilar metals unless in contact, with electrolyte
b) cannot occur if 2 metals have different electrolyte environments
c) occurs at the anode in a galvanic cell correct
d) cannot occur for 2 materials that have been dis-similarly stressed unless in contact
35. Anode:
a) corrosion never occurs here
b) dissolves in the electrolyte correct
c) does not undergo any type of chemical reaction
d) none of the above
36. Not a way to promote corrosion:
a) dissimilar metals
b) stress one material more than another
c) alter electrolyte
d) none of the above correct
37. In the galvanic series :
a) the end opposite gold is the more cathodic end
b) passive metals are more anodic than....??
c) active metals tend to have protective coatings on their surfaces
d) the same metal or alloy may be both active and passive correct
38. A metal:
a) that is more anodic will corrode rather than the one that is more cathodic only if connected and an electrolyte is present
b) in an electrolyte with a lower oxygen content is more cathodic than....??
c) with higher oxygen content in the electrolyte is more anodic than....??
d) none of the above
39. Corrosion can occur for: only if connected and an electrolyte is present
a) a metal with non uniform stresses
b) dissimilar metals
c) both a and b correct
d) none of the above
40. Micro cell corrosion:
a) can occur at grain boundaries
b) is promoted through segregation
c) can occur for multi phase materials
d) all of the above correct
41. In multiple phase micro cell corrosion:
a) the cathode would most likely be the precipitate particle
b) the anode would be the matrix material
c) the 2nd phase precipitates may dissolve at a different rate than the matrix phase correct
d) none of the above
42. Crevice corrosion:
a) the anode is on the surface of the metal
b) the cathode is in the crevice due to a low oxygen content in the electrolyte
c) the cathode would be where the higher oxygen content is in the electrolyte correct
d) both b and c
43. Setting up a galvanic cell:
a) blocks corrosion
b) initiates corrosion correct
c) only needs one electrode
d) has no impact on corrosion
44. When welding 304 SS:
a) the welding has no impact on possible corrosion
b) can promote corrosion correct
c) no HAZ exists
d) question does not make sense, it is impossible
45. The major factors in the selection of materials for design are:
a. Strength
b. Impact resistance
c. Corrosion resistance
d. a and c correct.........acrually any of these answers could be correct, depending upon the application!!!!
e. all of the above
46. Yield strength increases as: presumably the particle is a precipitate particle in an age hardened alloy
A) Both particle size and particle strength decrease
B) Particle size decreases and particle strength increases
C) Particle size increases and particle strength decreases
D) Both particle size and particle strength increase correct
47. Which of these factors affect the rate of corrosion?
a.) Temperature
b.) Humidity in the air
c.) The amount of salts dissolved in the air
d.) All of the above correct
48. Which type of precipitate particles would most likely be sheared by a dislocation:
a. Particles of medium size that are close together
b. Particles of large size that are close together
c. particles of small size that are close together correct
d. particles of large size that are far apart
49. Which material would be the best choice for a bicycle frame based solely on its yield/density factor?
a. 1080
b. 6061 - T6
c. Ti-3Al-2.5V correct
d. Cr-Mo steel
50. Which is true?
a) A substance which is corrosive will corrode other substances. correct
b) A substance that is corrodable will corrode other substances.
c) Stainless steels are noncorrosive; therefore they are always non-corrodable.
d) All of the above.
51. TIG welding:
a) Is a relatively violent process compared to arc welding
b) May need a filler rod; tungsten doesn't melt onto weld correct
c) Does not protect well against oxidation
d) Has a consumable electrode