Question 1

Which discontinuity appears as a straight, dark line in the center of the weld bead on a radiograph?

Accepted Answer

Incomplete penetration (IP) occurs at the root and appears as a straight, dark line in the center of the weld image on a radiograph.

Question 2

In a fillet weld fracture test, a 'wagon track' indication on the fracture surface typically represents:

Accepted Answer

'Wagon tracks' are elongated slag inclusions that form along the toes of a root pass (appearing as parallel lines) when the next pass is deposited without cleaning.

Question 3

A discontinuity that creates a sharp notch at the weld toe and reduces the cross-sectional thickness of the base metal is:

Accepted Answer

Undercut is the melting away of the base metal at the weld toe, leaving a groove (notch) that reduces thickness and creates a stress riser.

Question 4

Porosity that is elongated and worm-like in shape is referred to as:

Accepted Answer

Piping (or vermicular) porosity creates elongated, tubular voids often caused by gas escaping through solidifying metal.

Question 5

Which discontinuity is most likely caused by high travel speed?

Accepted Answer

High travel speed prevents the weld pool from wetting out properly and filling the void melted by the arc, resulting in undercut.

Question 6

A 'Fish Eye' is a discontinuity typically found on:

Accepted Answer

Fish eyes are small silvery spots (surrounding a pore or inclusion) on a fracture surface, caused by hydrogen embrittlement.

Question 7

Lack of Fusion (LOF) is best described as:

Accepted Answer

LOF (Cold Lap) is an adhesion failure where the weld metal does not metallurgically bond with the base metal or previous passes.

Question 8

Crater cracks are typically caused by:

Accepted Answer

Crater cracks (star cracks) form due to solidification shrinkage in the crater if the arc is broken abruptly without filling the crater.

Question 9

Which discontinuity is generally considered the most critical due to its tendency to propagate (grow)?

Accepted Answer

Cracks are sharp, planar defects that act as severe stress risers. They tend to propagate under load, leading to catastrophic failure.

Question 10

Arc strikes are detrimental because they:

Accepted Answer

The rapid heating and cooling of an arc strike creates a localized zone of hard, brittle martensite that often contains microcracks.

Question 11

Lamination is a base metal defect that is typically oriented:

Accepted Answer

Laminations are flattened imperfections (segregation/inclusions) from the steel rolling process, running parallel to the plate surface.

Question 12

In GMAW, 'Whiskers' are:

Accepted Answer

Whiskers occur when the wire passes through the root gap faster than it can melt, leaving a piece of wire sticking out the back side.

Question 13

Which condition is a result of excessive heat input in stainless steel?

Accepted Answer

Excessive heat maintains the steel in the sensitizing temperature range (800-1600°F), allowing chromium carbides to form.

Question 14

The term 'Sugaring' on a stainless steel root weld indicates:

Accepted Answer

Sugaring is a granular, oxidized surface on the root side of stainless steel caused by exposure to oxygen while hot (lack of backing gas).

Question 15

Hot cracking (solidification cracking) is typically located:

Accepted Answer

Hot cracks form during solidification as impurities with low melting points are pushed to the center, creating a weak centerline that tears under shrinkage stress.

Question 16

Underbead cracking is a form of:

Accepted Answer

Underbead cracks form in the HAZ after the weld has cooled (delayed cracking), driven by hydrogen and hardened microstructure.

Question 17

Which discontinuity is most associated with damp fluxes in SAW?

Accepted Answer

Moisture in SAW flux turns into steam in the arc, causing porosity (often wormhole/piping type) in the weld metal.

Question 18

A 'delamination' is:

Accepted Answer

When a lamination (which might be tight/invisible) opens up under the heat and stress of welding, it becomes a delamination.

Question 19

Excessive convexity in a fillet weld can lead to:

Accepted Answer

A steep angle at the toe (caused by convexity) acts as a stress riser (notch), significantly reducing fatigue life.

Question 20

Which of the following is considered a 'Planar' discontinuity?

Accepted Answer

Planar discontinuities are flat, 2-dimensional flaws (cracks, lack of fusion, laminations). Volumetric flaws are 3D (porosity, slag).

Question 21

Burn-through is caused by:

Accepted Answer

Burn-through is a hole melted completely through the base metal, caused by excessive amperage (heat) or waiting too long in one spot.

Question 22

A welder using GMAW has the gas flow rate set too high. This is likely to cause:

Accepted Answer

Excessive gas flow creates turbulence which pulls atmospheric air into the arc stream (venturi effect), causing porosity.

Question 23

Which discontinuity is a result of the arc deviating from its intended path (Magnetic Arc Blow)?

Accepted Answer

Arc blow causes the arc to wander erratically, leading to excessive spatter and often missing the joint edge (lack of fusion) or gouging the plate (undercut).

Question 24

Seams and laps are discontinuities found in:

Accepted Answer

Seams and laps are longitudinal surface defects originating from the steel mill rolling process, not the welding process.

Question 25

Base metal thickness is 1 inch. The welder leaves a 1/16 inch deep undercut. According to general workmanship standards, this is:

Accepted Answer

It is definitely a discontinuity. Whether it is a *defect* depends on the specific code criteria (e.g., D1.1 allows 1/32, so it would be a defect). The safest technical term for the physical feature itself is discontinuity.

Question 26

If a welder travels too slowly with SMAW, the most likely discontinuity is:

Accepted Answer

Traveling too slowly allows the molten puddle to roll ahead of the arc onto the cold base metal, causing overlap (cold lap) without fusion.

Question 27

Slag inclusions are most likely to occur in:

Accepted Answer

Slag inclusions require a process that uses flux (SMAW, FCAW, SAW). Gas-shielded processes (GMAW, GTAW) produce little to no slag, making inclusions rare (unless silica islands are trapped).

Question 28

Incomplete Joint Penetration (IJP) in a groove weld is defined as:

Accepted Answer

IJP means the weld metal does not reach the full depth required (usually full thickness for CJP welds). It is a root condition.

Question 29

Stray grinding marks on a radiograph appear as:

Accepted Answer

Grinding removes material, reducing thickness. Less thickness = more density on film = darker lines. They look like dark irregular scratches.

Question 30

A 'concave' root surface is acceptable in AWS D1.1 ONLY if:

Accepted Answer

Root concavity (suck-back) is permitted if the actual weld throat (including the concavity) meets the design thickness requirements.

Question 31

Tungsten inclusions are found only in:

Accepted Answer

Tungsten inclusions result from the non-consumable tungsten electrode touching the pool or melting. Only GTAW/PAW use tungsten electrodes.

Question 32

Which discontinuity is characterized by a jagged, branching appearance?

Accepted Answer

Cracks typically exhibit a jagged, branching path as they propagate through grain boundaries or lattice planes.

Question 33

During visual inspection of a pipe weld, you see 'High-Low'. This indicates:

Accepted Answer

High-Low is the industry term for internal or external misalignment of the pipe walls.

Question 34

Surface porosity is usually visible:

Accepted Answer

For flux processes, you must remove the slag to see surface-breaking pores. For GMAW/GTAW, it is visible immediately.

Question 35

A discontinuity that creates a straight, sharp-edged line at the weld interface on a radiograph is:

Accepted Answer

Lack of side wall fusion creates a very straight, distinct line where the original bevel face remains unfused.

Question 36

Spatter is defined as:

Accepted Answer

Spatter consists of molten droplets that fly out of the arc and stick to the base metal surface.

Question 37

When the weld face is below the adjacent base metal surface, it is called:

Accepted Answer

Underfill is the failure to fill the joint completely, leaving the weld surface below the base metal surface.

Question 38

Which discontinuity is associated with 'Chevron' cracks?

Accepted Answer

Chevron cracks are a specific type of Hydrogen Induced Crack found in submerged arc welds, angled at 45 degrees in a stepped pattern.

Question 39

Excessive weld metal buildup on a groove weld is called:

Accepted Answer

Reinforcement is the proper term for weld metal in excess of the quantity required to fill the groove.

Question 40

Which defect is detected by a 'bend test' but might be missed by radiography?

Accepted Answer

Tight lack of fusion is a planar defect. If the X-ray beam is not oriented perfectly parallel to it, it may not show up. A bend test will mechanically open it up.

Discontinuity Identification Practice Questions

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