Manufacturing Engineering Multiple Choice Questions on “Welding Metallurgy and Welding Defects”.
1. Which of the following defects occur due to flux employed and electrode coating?
a) Inclusion of slag
b) Inadequate penetration
c) Incomplete fusion
d) Porosity
Answer: a
Clarification: Slag inclusions are one of the main weld defects. If we don’t properly clean the slag from a bead, we run the risk of it becoming part of the weld when we run the next bead. A good welder will generally burn it out on the next pass, but if not, there will be a chunk of slag in the bead which leaves a weak spot. Slag inclusions.
2. Which of the following defects occur when the deposited metal is not focused on the root of weld?
a) Inclusion of slag
b) Inadequate penetration
c) Incomplete fusion
d) Porosity
Answer: b
Clarification: Inadequate penetration defects occur when the deposited metal is not focused at the root of weld. Some part of gap remains unwelded due to this defect.
3. Which of the following defects occur when weld metal layer fails to fuse together?
a) Inclusion of slag
b) Inadequate penetration
c) Incomplete fusion
d) Porosity
Answer: c
Clarification: Incomplete fusion defects occur when weld metal layer fails to fuse together. It causes discontinuity in weld zone.
4. Which of the following defects occur due to the entrapment of gas bubbles by the freezing dendrites during the cooling of molten pad?
a) Inclusion of slag
b) Inadequate penetration
c) Incomplete fusion
d) Porosity
Answer: d
Clarification: Referred to as worm holes, these are gas pockets trapped in the weld. A couple of reasons would be from not enough shielding gas in MIG, or moisture in the flux.
5. Which of the following defects occur due to filler material having a different rate of contraction compared to parent metal?
a) Undercut
b) Spatter
c) Cracking in weld metal
d) Cold cracking
Answer: c
Clarification: Weld cracking occurs close to the time of fabrication. Most forms of cracking result from the shrinkage strains that occur as the weld metal cools. It can be of hot cracks types.
6. Which of the following defects occur due to melting or burning away of base metal?
a) Undercut
b) Spatter
c) Cracking in weld metal
d) Cold cracking
Answer: a
Clarification: Undercut is the cardinal sin of welding grasshopper! Cutting into the steel with the force of the arc leaves a cut out groove in the weld. If this is not filled back in with filler metal, it leaves a weld defect which is a weak point that can cause the joint to fail. This can cause property damage, injury and even loss of life.
7. Which of the following defects occur due to scattering of metal around the vicinity of weld?
a) Undercut
b) Spatter
c) Cracking in weld metal
d) Cold cracking
Answer: b
Clarification: Spatters are the droplets of molten material during GAS welding or arc welding. A temperature difference and slag accumulation are the reason of spatter formation. Welding speed is also one of the main causes of spatter. Type of material used and type of welding also decide to spatter density.
8. Which of the following defects occur due to incorrect welding techniques?
a) Undercut
b) Hot cracking
c) Cracking in weld metal
d) Cold cracking
Answer: c
Clarification: Cracking in weld metal defect occur due to incorrect welding techniques. Sometimes cracking may not be visible by naked eyes.
9. Which of the following defect is influenced by sulphur and carbon content of weld metals?
a) Undercut
b) Hot cracking
c) Cracking in weld metal
d) Cold cracking
Answer: b
Clarification: Hot cracks are those that occur at elevated temperatures and are usually solidification related. It is being influenced by sulphur and carbon content of weld metals. Sometimes cracking may not be visible by naked eyes.
10. Which of the following defects occur at a lower temperature?
a) Undercut
b) Hot cracking
c) Cracking in weld metal
d) Cold cracking
Answer: d
Clarification: Cold cracks are those that occur after the weld metal has cooled to room temperature and may be hydrogen related. These occurs are lower temperature. Sometimes cracking may not be visible by naked eyes.