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問題一覧
1
What current type produces good penetration and oxide removal when using GTAW on aluminum?
ac with continuous high frequency current
2
Water pressure on a GTaw torch should NOT exceed:
The manufacturer's recommendations
3
What is a likely cause of lack of fusion?
Arc length that is too long
4
Contaminated shielding gas generally causes:
porosity
5
Tungsten inclusions in The weld zone are most often caused by:
exceeding the current limit of the electrode
6
A GTAW electrode that discolours when the arc is broken is an indication that:
the electrode has atmospheric contamination
7
Using direct current reverse polarity with GTAW:
requires the use of larger electrodes
8
The end of the gas nozzle must be kept clean and uniform in order to avoid:
uneven gas coverage
9
Why is argon hydrogen shielding NOT recommended for carbon steels?
hydrogen becomes dissolved in carbon steals and causes hydrogen embrittlement that may lead to cracking
10
With the machine running, what is most likely to be the problem when you are unable to start an arc?
The work lead is not attached or they lead to work connection is faulty
11
Excessive shielding gas flow may result in:
contamination of the weld puddle
12
What can happen if the torch body or handle becomes cracked?
a possible shock hazard from the high frequency current can occur.
13
A reason for undercut in GTAW weld is:
welding current that is set too high
14
When installing electrical powered welding machines, the installation must comply with:
applicable local electrical codes
15
Why must collets be kept clean?
keeping collets clean ensures that the best electrical contact can be obtained between the electrode and the collet to reduce heating of the electrode and the torch body
16
GTAW troubleshooting can be grouped into one of which three categories? a) b) c)
process mechanical electrical
17
Badly discolored cable lugs indicate that the connection has:
overheated during use
18
If you strike an arc and immediately experience atmospheric contamination, what part of the equipment may not be properly adjusted?
the flow meter
19
What is the likely cause of porosity in a GTAW weld?
inadequate gas shielding
20
What may occur if the gas hose fittings are not tightly secured?
atmospheric air can be drawn in to the shielding gas or a loss of shielding can contaminate the weld and/or the electrode
21
Metal particle sticking to the inside of the ceramic nozzle May:
cause gas turbulence and possible atmospheric contamination
22
Incomplete penetration could be caused by:
Arc length that is too long
23
One reason for crater cracks occurring at the end of the weld is:
improper manipulation of the torch
24
What shielding gas is the best choice to aid in oxide removal on aluminum?
Argon
25
High frequency current leakage can be prevented by:
keeping the welding cables as short and straight as possible
26
Continuous high frequency current may be required with GTAW when:
you are using alternating current
27
One reason for a crack in the weld is?
The wrong combination of filler to base metal
28
What are symptoms of creep on a shielding gas regulator?
creep is identified when the working pressure gauge shows an increase pressure after the cylinder is opened while adjustment screw is disengaged
29
Why must metal components be grounded when high frequency current is used?
high frequency current radiation must be controlled to prevent radio and television interference
30
What is the purpose of tailing out prior to breaking the arc?
to reduce the size of the weld puddle to prevent crater cracking
31
Root pass suckback is the result of:
improper position of filler metal addition.