IET 170 exam 2 (Ritter) || with Complete Solutions.
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Course
IET 170
Institution
IET 170
23. What sorts of problems plagued early attempts to develop arc welding? correct answers - by instability of the arc, which required great amount of skill to maintain
-contamination & oxidation of the weld metal resulted from an atmospheric exposure at such high temps
- metallurgical effects...
IET 170 exam 2 (Ritter) || with Complete Solutions.
23. What sorts of problems plagued early attempts to develop arc welding? correct answers - by
instability of the arc, which required great amount of skill to maintain
-contamination & oxidation of the weld metal resulted from an atmospheric exposure at such
high temps
- metallurgical effects of such a process were not well understood in early attempts to develop
arc welding
24. What are the three types of current and polarity that are used in arc welding? correct answers
- alternating current
- straight polarity direct current (workpiece is positive)
-reversed polarity direct current (workpiece is negative)
26. What is the difference between a consumable and nonconsumable electrode?
For which processes does a filler metal have to be added by a separate mechanism? correct
answers - for the consumable electrode processes the electrode melts to supply the needed filler
metal to fill the voids in the joint
- with a nonconsumable electrode a separate metal wire must be used to supply the filler metal
27. What are the three types of metal transger that can occur during arc welding? correct answers
- globular
- spray
- short circuit
28. What are some of the process variables that must be specified when setting up an arc-welding
process? correct answers arc welding processes require the specification are:
- welding voltage
- welding current
- arc polarity
- arc length
- welding speed
- arc atmosphere
- electrode of filler material
- flux
32. How are welding electrodes commonly classified, and what information does the designation
usually provide? correct answers - tensile strength of the deposit weld metal
- welding position in which they may be used
- type of current & polarity (if a direct current)
33. Why are shielded metal arc electrodes often baked just prior to welding? correct answers to
remove all moisture from their coating, and source of hydrogen in the welds
, 34. What are the functions of the fluxing constituents and slag coating that forms over a shielded
metal arc weld? correct answers - capture impurities that float to the surface
- protect the cooling metal from oxidation & slows down the cooling rate if the weld metal to
prevent hardening
36. Why are shielded metal arc electrodes generally limited in length, forcing the process to be
one of the intermittent operation? correct answers continuous shielded metal arch welding faces
the problem of providing electrical contact (through the coating) to the center filler-metal wire
38. What are some of the attractive features of the shielded metal arc welding process? correct
answers - simple
- inexpensive
- versatile
- require only a power supply
- cables
- an electrode holder
- a supply of stick electrodes
41. What are some of the advantages of gas metal arc welding compared to the shielded metal
arc process? correct answers - there is no need for flux so the electrode can be an uncoated,
continuous, solid wire
- it can be applied to all metals
- the heat transfer and weld penetration can be somewhat controlled by choice of shielding gas
42. Describe the relative performance of argon, helium, and carbon dioxide gases in creating a
high-temp arc and promoting weld penetration. correct answers - Helium produces the hottest arc
and deepest weld penetration
- Carbon dioxide provides the lowest arc temps, shallowest penetration arc stability, and reduces
weld spatter
- Argon produces temps and a penetration intermediate between Helium & Carbon dioxide
it's heavier than air, it covers the weld area with the use of low gas flow rates
54. What are some of the attractive features of submerged arc welding?
Major limitations? correct answers - high welding speeds
- high deposition rates
-deep penetration
-extensive flux handling
- possible contamination of the flux by moisture
- large volume of slag needs to be removed
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