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I-CAR AWQT practice questions

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Question 1Welding Safety and Personal Protective Equipment

When arc welding with a SMAW electrode, which PPE item is the primary defense against ultraviolet and infrared radiation damage to the eyes and face?

  1. A hard hat with an attached ear muff
  2. A disposable dust mask with a splash guard
  3. A welding helmet with a properly shaded filter lens Correct answer.
  4. Clear safety glasses worn under a face shield

Explanation

The welding helmet filter lens is rated by shade number to block the specific ultraviolet and infrared wavelengths produced by the arc. Clear safety glasses do not block enough radiation intensity and are worn only as secondary eye protection under the helmet.

Question 2Welding Safety and Personal Protective Equipment

What is the correct shade number selection for shielded metal arc welding at 100 amps according to typical safety guidance?

  1. Shade 3 to 4
  2. Shade 6 to 7
  3. Shade 10 to 11 Correct answer.
  4. Shade 14 only

Explanation

Published shade guides tie lens darkness to welding process and current. For SMAW at roughly 100 amps, a shade in the 10 to 11 range is the standard recommendation. Lighter shades are used for lower-current processes such as gas tungsten arc welding.

Question 3Welding Safety and Personal Protective Equipment

Which glove specification best protects a welder's hands during out-of-position stick welding with spatter falling toward the wrists?

  1. Cotton jersey work gloves
  2. Coated knit mechanic gloves
  3. Gauntlet-style leather welding gloves Correct answer.
  4. Thin nitrile exam gloves

Explanation

Gauntlet leather gloves extend up the forearm and resist spatter and heat, which is what out-of-position stick welding demands. Thin or knit gloves melt, burn, or transmit heat and are not rated for welding.

Question 4Welding Safety and Personal Protective Equipment

Why should welding sleeves or a jacket be worn rather than rolling up shirt sleeves during overhead welding?

  1. Bare skin absorbs shielding gas more readily
  2. Rolled sleeves increase the risk of electric shock from the electrode holder
  3. Bare arms interfere with the shielding gas flow
  4. Exposed skin is vulnerable to spatter burns and UV radiation burns Correct answer.

Explanation

Overhead welding drops molten spatter and exposes the arms to intense UV light. Covered arms with flame-resistant sleeves prevent both spatter burns and the radiation burn often called arc flash.

Question 5Welding Safety and Personal Protective Equipment

A welder must weld inside a confined space where ventilation cannot maintain safe fume levels. What is the appropriate respiratory protection decision?

  1. Hold your breath during short welds
  2. Use a half-mask dust mask and continue welding
  3. Rely on the welding helmet to filter fumes
  4. Wear a supplied-air respirator approved for the exposure Correct answer.

Explanation

When engineering controls cannot keep fume and gas exposure below limits in a confined space, an approved supplied-air respirator is required. Air-purifying masks may not handle oxygen deficiency or certain gases and are not a substitute for supplied air in confined spaces.

Question 6Welding Safety and Personal Protective Equipment

Which statement correctly describes the purpose of a welding helmet's auto-darkening filter?

  1. It filters shielding gas before it reaches the breathing zone
  2. It darkens instantly when the arc strikes and returns to a light state when the arc stops Correct answer.
  3. It provides impact protection only and does not change shade
  4. It permanently stays at one dark shade regardless of arc

Explanation

An auto-darkening filter senses the arc and switches rapidly to the set shade, then lightens when the arc ends. This lets the welder see clearly while positioning without lifting the helmet, while still protecting the eyes during the arc.

Question 7Welding Safety and Personal Protective Equipment

What is the main hazard of wearing synthetic clothing such as polyester under a welding jacket?

  1. It blocks the shielding gas from reaching the weld
  2. It melts and adheres to skin when struck by spatter Correct answer.
  3. It conducts electricity toward the welder
  4. It attracts magnetic arc blow

Explanation

Synthetic fabrics can melt and stick to the skin when hot spatter lands on them, producing severe burns. Wool, heavy cotton, and leather are preferred because they char rather than melt.

Question 8Welding Safety and Personal Protective Equipment

Before striking an arc, a welder notices the electrode holder has cracked insulation near the jaws. What is the correct action?

  1. Weld at lower amperage to reduce risk
  2. Wear rubber gloves and proceed
  3. Wrap the crack with electrical tape and weld
  4. Replace the holder before welding Correct answer.

Explanation

Cracked insulation on an electrode holder exposes the welder to the open-circuit voltage of the machine. The holder must be taken out of service and replaced rather than taped or worked around.

Question 9Welding Safety and Personal Protective Equipment

Why must a welder avoid welding on a workpiece that is wet or standing in water?

  1. Water makes the shielding gas flammable
  2. Water increases the risk of electric shock through the welder's body Correct answer.
  3. Water changes the metallurgy of the weld
  4. Water prevents the electrode from striking an arc

Explanation

Water lowers resistance between the welder and ground, raising the chance that current passes through the body. Welding should be done on dry surfaces with dry gloves to reduce shock risk.

Question 10Welding Safety and Personal Protective Equipment

Which fire watch requirement applies to welding near combustible materials?

  1. A fire watch is only required indoors
  2. A fire watch is needed only if flames are visible
  3. A fire watch may leave once the arc is extinguished
  4. A fire watch must remain during welding and for a period after to catch smoldering fires Correct answer.

Explanation

Hot spatter and slag can start smoldering fires that ignite after welding stops. A fire watch stays through the work and for a specified period afterward to detect and extinguish these hidden fires.

Question 11Welding Safety and Personal Protective Equipment

What is the primary function of fume extraction at the arc during welding?

  1. To cool the weld bead faster
  2. To reduce the arc voltage
  3. To capture fume and gases near the source before they enter the breathing zone Correct answer.
  4. To increase the shielding gas flow rate

Explanation

Source capture, such as a fume extraction gun or a hood positioned at the arc, removes fume and gases before they disperse into the welder's breathing zone. It is an engineering control that reduces exposure without relying on the welder's behavior.

Question 12Welding Safety and Personal Protective Equipment

A welder is tack welding in a shop where other workers are nearby without eye protection. What is the appropriate control?

  1. Use welding screens or curtains to shield the arc from bystanders Correct answer.
  2. Ask bystanders to look away during the arc
  3. Turn off the shop lights while welding
  4. Weld quickly so the arc is brief

Explanation

Arc radiation can injure the eyes of anyone in line of sight, causing flash burn. Opaque welding screens or curtains block the arc from bystanders and are the standard control in shared work areas.

Question 13Welding Safety and Personal Protective Equipment

Which hearing protection concern applies when welding in a shop with high noise from grinding and plasma cutting?

  1. Noise exposure is only a concern for the grinder operator
  2. Hearing protection should be selected to reduce noise to a safe level while still allowing warning signals Correct answer.
  3. Hearing protection is unnecessary because the welding helmet covers the ears
  4. Ear plugs must never be worn during welding

Explanation

Noise from grinding, plasma cutting, and chipping adds to the welder's exposure. Hearing protection should lower exposure below safe limits without blocking the ability to hear alarms and coworkers.

Question 14Welding Safety and Personal Protective Equipment

What hazard does galvanized steel present during welding that requires specific respiratory precautions?

  1. It causes the arc to extinguish repeatedly
  2. It produces excessive shielding gas
  3. It releases zinc oxide fume that can cause metal fume fever Correct answer.
  4. It creates a magnetic field that deflects the arc

Explanation

Welding galvanized steel vaporizes zinc coating and produces zinc oxide fume, which can cause metal fume fever. Adequate ventilation, source extraction, or respiratory protection is needed to control exposure.

Question 15Welding Safety and Personal Protective Equipment

When selecting a welding helmet, which feature most directly reduces the risk of arc flash reaching the eyes during tack welding?

  1. A built-in grinding mode
  2. A lightweight shell material
  3. A short switching delay in the auto-darkening filter Correct answer.
  4. A large viewing area

Explanation

A short switching delay means the filter darkens almost instantly when the arc starts, limiting the brief unprotected exposure that can cause flash burn during repeated tacks. Viewing area and shell weight do not affect radiation protection.

Question 16Welding Safety and Personal Protective Equipment

A welder using a supplied-air respirator reports the air feels warm and the flow seems low. What is the correct response?

  1. Switch to a dust mask and continue
  2. Stop work and check the air supply and flow per the respirator program Correct answer.
  3. Continue welding and increase the welding current
  4. Remove the respirator and breathe through the nose

Explanation

Low or warm air flow may indicate a supply problem that could leave the welder without adequate breathing air. Work should stop and the air supply, flow rate, and equipment checked according to the respirator program.

Question 17Welding Safety and Personal Protective Equipment

Which combination best protects a welder performing overhead welding in a shop with moderate fume?

  1. Nitrile gloves, face shield, and open doors
  2. Leather jacket, gauntlet gloves, welding helmet, and source-capture fume extraction Correct answer.
  3. Cotton t-shirt, safety glasses, and a box fan
  4. Coveralls, dust mask, and ear plugs

Explanation

Overhead work needs flame-resistant coverage for the arms and torso, gauntlet gloves, and a shaded helmet, plus fume control for the breathing zone. Source-capture extraction addresses fume at the arc rather than relying on general dilution.

Question 18Welding Safety and Personal Protective Equipment

What is the purpose of flashback arrestors on oxyfuel gas welding equipment?

  1. To increase the flame temperature
  2. To filter metal fume from the breathing zone
  3. To reduce the shielding gas flow
  4. To prevent a flame from traveling back into the hoses and cylinders Correct answer.

Explanation

Flashback arrestors stop a flame or explosion from propagating backward through the hose into the regulator and cylinder. They are a critical safety device on oxyfuel torch setups.

Question 19Welding Safety and Personal Protective Equipment

Why is it important to inspect welding gloves for holes before use?

  1. Holes change the shielding gas composition
  2. Holes allow spatter and heat to reach the skin and can admit current path Correct answer.
  3. Holes cause the electrode to stick
  4. Holes reduce the welder's grip strength

Explanation

A hole in a welding glove lets molten spatter and heat reach the skin and can also expose the hand to electrical contact. Damaged gloves should be replaced before welding.

Question 20Welding Safety and Personal Protective Equipment

Which practice best reduces UV exposure to the neck and chest when welding out of position?

  1. Wearing a shirt with an open collar
  2. Relying on sunscreen alone
  3. Welding with the helmet raised
  4. Using a helmet with a leather bib or flame-resistant collar Correct answer.

Explanation

Reflected and scattered arc radiation can reach the neck and chest below the helmet. A leather bib or flame-resistant collar covers that gap, while an open collar leaves skin exposed.

Question 21Welding Safety and Personal Protective Equipment

A welding helmet lens is scratched and cloudy. What is the correct action?

  1. Polish it with solvent and keep welding
  2. Weld without the lens
  3. Replace the lens or cover plate to maintain visibility and protection Correct answer.
  4. Continue using it since the shade number is unchanged

Explanation

Scratched or cloudy lenses reduce visibility, which can lead to unsafe positioning and errors, and may compromise the filter. The lens or protective cover plate should be replaced.

Question 22Welding Safety and Personal Protective Equipment

Which statement about welding in a confined space is correct?

  1. The welder should work alone to reduce crowding
  2. The space may be entered without testing if it looks clean
  3. Ventilation is unnecessary if the weld is short
  4. A standby attendant should monitor the welder and the space during the work Correct answer.

Explanation

Confined space welding requires atmospheric testing, ventilation, and a standby attendant who monitors conditions and can summon help. Working alone or skipping testing removes the safeguards that prevent asphyxiation and fume exposure.

Question 23Welding Safety and Personal Protective Equipment

What is the correct way to store welding helmets with auto-darkening filters between shifts?

  1. Store them in a clean, dry place away from extreme heat and impact Correct answer.
  2. Store them in a wet rag to keep the lens cool
  3. Stack heavy tools on top of them
  4. Leave them in direct sunlight to keep the solar cells charged

Explanation

Auto-darkening filters contain electronics and solar cells that can be damaged by extreme heat, moisture, and impact. Clean, dry storage away from heat and heavy objects preserves function and lens clarity.

Question 24Welding Safety and Personal Protective Equipment

A welder notices a mild tingling sensation when touching the workpiece with bare hands while the machine is on. What does this most likely indicate and what action is required?

  1. Normal operation; continue welding
  2. The shielding gas is too low; increase flow
  3. The electrode is too small; change electrode size
  4. A possible ground or insulation fault; stop and have the equipment checked Correct answer.

Explanation

Tingling suggests stray current from a ground or insulation fault in the welding circuit. The equipment should be taken out of service and inspected by a qualified person before further use.

Question 25GMAW (MIG) Welding Theory and Equipment Setup

In GMAW, which shielding gas is most commonly used for short-circuit transfer on thin sheet steel because it provides good arc stability at low current?

  1. 100% argon
  2. 75% argon / 25% CO2 Correct answer.
  3. 100% helium
  4. 90% helium / 7.5% argon / 2.5% CO2

Explanation

Argon-rich argon/CO2 mixtures stabilize the low-current arc needed for short-circuit transfer on thin steel and reduce spatter compared with high-CO2 blends. Pure argon is not used on carbon steel because it gives poor penetration and an unstable arc, and helium blends are chosen for high-heat situations.

Question 26GMAW (MIG) Welding Theory and Equipment Setup

What is the primary function of the contact tip in a GMAW gun?

  1. To feed wire at a constant rate
  2. To cool the nozzle assembly
  3. To transfer welding current to the electrode wire Correct answer.
  4. To regulate gas flow at the nozzle

Explanation

The contact tip is the electrical junction where welding current passes from the gun to the consumable wire as it leaves the gun. Wire feed rate is set by the drive rolls, gas flow is controlled at the regulator, and cooling is handled by the gun's duty cycle and, in some guns, water circulation.

Question 27GMAW (MIG) Welding Theory and Equipment Setup

On a GMAW machine, increasing wire feed speed while holding voltage constant will generally:

  1. Have no effect on amperage, only on gas flow
  2. Decrease amperage and decrease deposition rate
  3. Increase voltage and narrow the arc
  4. Increase amperage and increase deposition rate Correct answer.

Explanation

Wire feed speed determines how much wire is fed into the arc, so raising it increases current (amperage) and melt-off, raising deposition rate. Voltage is a separate setting controlled by the machine's output, so it does not change just because wire feed speed is increased.

Question 28GMAW (MIG) Welding Theory and Equipment Setup

Which GMAW metal transfer mode is characterized by a fine, rapid series of short circuits as the wire touches the puddle and pinches off?

  1. Short-circuiting transfer Correct answer.
  2. Pulsed spray transfer
  3. Spray transfer
  4. Globular transfer

Explanation

Short-circuiting transfer occurs at low voltage and current, where the wire contacts the puddle and extinguishes the arc, then pinches off and re-establishes the arc many times per second. Spray transfer uses a fine axial droplet stream without short circuits, and globular transfer produces large irregular droplets.

Question 29GMAW (MIG) Welding Theory and Equipment Setup

What does the term "duty cycle" mean on a GMAW power source rated at 60% duty cycle?

  1. The machine can weld 6 minutes out of every 10 at rated output Correct answer.
  2. The machine delivers 60% of its rated amperage continuously
  3. The machine must rest 6 minutes after every 4 minutes of welding
  4. The gas solenoid stays open 60% of the time

Explanation

Duty cycle is the percentage of a 10-minute period a power source can operate at rated output without overheating. A 60% rating means 6 minutes of welding at rated amperage followed by 4 minutes of cooling, and higher amperage shortens the allowable on-time.

Question 30GMAW (MIG) Welding Theory and Equipment Setup

Which drive roll configuration is best suited for feeding solid carbon steel MIG wire without deforming it?

  1. Smooth V-groove rolls Correct answer.
  2. Knurled V-groove rolls
  3. U-groove rolls with serrated teeth
  4. Flat rolls with no groove

Explanation

Smooth V-groove rolls grip solid wire with enough friction to feed it while avoiding surface deformation that could cause feed problems. Knurled or serrated rolls are intended for flux-cored wire, and ungrooved flat rolls do not guide the wire reliably.

Question 31GMAW (MIG) Welding Theory and Equipment Setup

Which parameter primarily controls arc length in GMAW?

  1. Wire feed speed
  2. Gas flow rate
  3. Travel speed
  4. Voltage Correct answer.

Explanation

In GMAW, voltage sets arc length: higher voltage lengthens the arc and flattens the bead, while lower voltage shortens it. Wire feed speed mainly controls current and deposition, gas flow affects shielding, and travel speed affects bead size and penetration.

Question 32GMAW (MIG) Welding Theory and Equipment Setup

A welder notices porosity along the top of a GMAW bead on steel. Which setup issue is the most likely cause?

  1. Too much travel speed reduction
  2. Excessive wire feed speed
  3. Insufficient shielding gas flow or a blocked nozzle Correct answer.
  4. Contact tip recessed too far inside the nozzle

Explanation

Porosity usually indicates atmospheric contamination of the molten weld, commonly from low gas flow, a clogged nozzle, or drafts. Excessive wire feed speed and travel changes affect bead shape and penetration but do not by themselves introduce gas into the weld.

Question 33GMAW (MIG) Welding Theory and Equipment Setup

In the GMAW process, what does the term "inductance" control on many power sources?

  1. The rate of current rise during a short circuit Correct answer.
  2. The open-circuit voltage limit
  3. The wire feed motor torque
  4. The total shielding gas pressure

Explanation

Inductance settings influence how quickly current rises when the wire short-circuits the puddle, which affects spatter and arc stability in short-circuit transfer. It does not set gas pressure, motor torque, or open-circuit voltage.

Question 34GMAW (MIG) Welding Theory and Equipment Setup

Which condition would most likely cause a GMAW arc to stutter and the wire to burn back to the contact tip?

  1. Voltage set too low for the wire feed speed Correct answer.
  2. Contact tip too far from the work
  3. Gas flow set too high
  4. Travel speed set too slow

Explanation

When voltage is too low for the wire feed speed, the wire cannot melt fast enough and burn-back occurs, stubbing the tip. Excess gas flow, slow travel, and excessive stick-out change other characteristics but do not cause burn-back in the same way.

Question 35GMAW (MIG) Welding Theory and Equipment Setup

When setting up a GMAW machine for spray transfer on thick steel, which shielding gas composition is typically required?

  1. 98% argon / 2% oxygen Correct answer.
  2. 100% CO2
  3. 75% argon / 25% CO2
  4. 100% nitrogen

Explanation

Spray transfer requires a high argon content (typically 85% or more) with a small oxygen or CO2 addition to stabilize the arc and improve wetting. High-CO2 blends promote short-circuit or globular transfer, and nitrogen is not a shielding gas for steel GMAW.

Question 36GMAW (MIG) Welding Theory and Equipment Setup

What is the recommended practice for setting shielding gas flow rate on a GMAW regulator?

  1. Set it to zero and rely on the wire coating for shielding
  2. Set it to the range recommended for the application, typically 30-50 CFH indoors Correct answer.
  3. Set it to match the wire feed speed in inches per minute
  4. Set it as high as the regulator allows to guarantee coverage

Explanation

Gas flow should be set within a recommended range, commonly about 30-50 cubic feet per hour for many indoor steel applications, using a flowmeter. Excessive flow creates turbulence that draws in air, and flow is not tied directly to wire feed speed.

Question 37GMAW (MIG) Welding Theory and Equipment Setup

A welder switches from 0.030 in. to 0.045 in. solid wire but keeps the same drive rolls and liner. What is the most likely consequence?

  1. Improved wire feeding with less friction
  2. Wire feeding problems from mismatched drive roll groove and liner size Correct answer.
  3. Automatic increase in arc voltage
  4. Reduced need for shielding gas

Explanation

Drive rolls and liners are sized to the wire diameter, so running larger wire through 0.030 in. components causes poor grip, slipping, and birdnesting. Voltage does not change automatically, and gas requirements remain.

Question 38GMAW (MIG) Welding Theory and Equipment Setup

Which GMAW gun angle and travel direction is generally recommended for flat-position fillet welds on steel?

  1. A 45-degree perpendicular angle with no tilt
  2. A 90-degree angle pointing straight down
  3. A drag angle of 10-15 degrees, pushing the puddle
  4. A push angle of 10-15 degrees, leading the puddle Correct answer.

Explanation

A slight push (forehand) angle of about 10-15 degrees improves visibility and gives good penetration and bead appearance on flat fillets. Excessive drag or perpendicular angles can reduce penetration control and shield gas poorly.

Question 39GMAW (MIG) Welding Theory and Equipment Setup

What is the purpose of the liner in a GMAW gun?

  1. To mix shielding gases before the nozzle
  2. To conduct welding current to the wire
  3. To insulate the gun from the work lead
  4. To guide the electrode wire from the drive rolls to the contact tip Correct answer.

Explanation

The liner provides a low-friction path that guides the wire from the drive rolls through the gun cable to the contact tip. Current is transferred at the contact tip, and the liner has no role in gas mixing or grounding.

Question 40GMAW (MIG) Welding Theory and Equipment Setup

When a GMAW weld shows excessive spatter and a ropey bead on steel short-circuit transfer, which adjustment is most appropriate?

  1. Increase wire feed speed sharply and reduce voltage
  2. Switch to pure argon shielding gas
  3. Increase voltage slightly and verify inductance settings Correct answer.
  4. Decrease gas flow and increase travel speed

Explanation

Ropey beads and heavy spatter in short-circuit transfer often indicate voltage that is too low or inductance set poorly for the wire feed speed. Raising voltage slightly and tuning inductance improves arc stability and spatter. Pure argon is unsuitable for steel, and reducing gas flow worsens shielding.

Question 41GMAW (MIG) Welding Theory and Equipment Setup

What is the typical maximum recommended stick-out for short-circuit GMAW on steel to maintain stable transfer?

  1. About 3/4 to 1 inch
  2. About 1-1/2 inches
  3. About 2 inches
  4. About 1/4 to 3/8 inch Correct answer.

Explanation

Short-circuit transfer generally uses a short stick-out, roughly 1/4 to 3/8 inch, so the arc stays stable and shielding is maintained. Longer stick-out reduces current, can cause stubbing, and increases the chance of losing gas coverage.

Question 42GMAW (MIG) Welding Theory and Equipment Setup

Which factor most directly determines whether a GMAW setup achieves spray transfer rather than globular transfer?

  1. The color of the wire spool
  2. The current density relative to wire diameter and the shielding gas composition Correct answer.
  3. The length of the work lead
  4. The size of the gas nozzle

Explanation

Spray transfer requires current above a transition level determined by wire diameter and a high-argon shielding gas; below that level transfer is globular or short-circuiting. Spool color, work lead length, and nozzle size do not set the transfer mode.

Question 43GMAW (MIG) Welding Theory and Equipment Setup

A GMAW power source is set to constant voltage (CV). What does the machine do as the arc length changes?

  1. It varies wire feed speed to hold amperage constant
  2. It shuts off the arc when voltage changes
  3. It holds voltage nearly constant while current changes with arc length Correct answer.
  4. It increases gas flow to stabilize the arc

Explanation

In CV operation the power source maintains a nearly constant voltage while current varies with arc length, which is why wire feed speed sets the current. This self-regulating behavior is central to GMAW, unlike constant-current processes such as stick welding.

Question 44GMAW (MIG) Welding Theory and Equipment Setup

Which GMAW setup problem is most likely when the wire feeds erratically and forms a tangle at the drive rolls?

  1. Too much shielding gas
  2. Voltage set too high
  3. Excessive drive roll tension or a worn liner Correct answer.
  4. Travel speed set too fast

Explanation

Birdnesting at the drive rolls usually results from excessive drive roll tension, a kinked or worn liner, or a clogged contact tip that stops the wire. Gas flow, voltage, and travel speed do not cause the wire to tangle at the feed rolls.

Question 45GMAW (MIG) Welding Theory and Equipment Setup

When welding aluminum with GMAW, why is push (forehand) technique generally preferred over drag?

  1. It increases wire feed speed automatically
  2. It allows the use of CO2 shielding gas
  3. It improves cleaning action and reduces oxide inclusion ahead of the puddle Correct answer.
  4. It eliminates the need for argon shielding

Explanation

Pushing the gun on aluminum provides better cleaning action and helps break up surface oxide ahead of the puddle, improving weld quality. It does not change wire feed speed automatically, and aluminum GMAW still requires argon or argon/helium shielding, not CO2.

Question 46GMAW (MIG) Welding Theory and Equipment Setup

A welder is using a 75% argon / 25% CO2 blend and switches to 90% argon / 10% CO2 on the same steel joint. What change should be expected?

  1. Spray transfer becomes possible at higher currents and penetration characteristics change Correct answer.
  2. Penetration becomes deeper in all cases
  3. Shielding gas is no longer needed
  4. The arc becomes unusable at any current

Explanation

Increasing argon content allows the transition to spray transfer at higher currents and changes penetration profile and bead shape compared with a 75/25 blend. The arc remains usable, shielding is still required, and deeper penetration is not guaranteed across all conditions.

Question 47GMAW (MIG) Welding Theory and Equipment Setup

Which combination best explains why a GMAW weld on steel shows lack of fusion at the sidewalls?

  1. Inductance set too high and travel angle pushing
  2. Contact tip too close and travel speed too slow
  3. Gas flow too high and wire too large
  4. Travel speed too fast and voltage too low for the joint Correct answer.

Explanation

Lack of sidewall fusion commonly results from excessive travel speed combined with low voltage, which reduces heat input and prevents the arc from wetting into the joint sides. High gas flow, tip distance, and inductance affect stability but are not the primary cause of cold lap.

Question 48GMAW (MIG) Welding Theory and Equipment Setup

In pulsed spray GMAW, what is the role of the background current?

  1. It sets the wire feed motor speed
  2. It replaces the need for a contact tip
  3. It maintains the arc between pulses and controls average heat input Correct answer.
  4. It determines the shielding gas composition

Explanation

Pulsed spray alternates between a peak current that detaches droplets and a lower background current that keeps the arc established between pulses. Adjusting the background level helps control average current and heat input, which is valuable on thin or heat-sensitive material.

Question 49GMAW (MIG) Welding Theory and Equipment Setup

A GMAW operation on stainless steel is producing a dark, heavily oxidized bead and poor corrosion resistance. Which setup change addresses the root cause?

  1. Increase stick-out to 1 inch
  2. Reduce gas flow to prevent turbulence
  3. Switch to a tri-mix shielding gas with higher argon and add adequate gas coverage Correct answer.
  4. Increase CO2 content to 25% for better penetration

Explanation

Heavy oxidation and reduced corrosion resistance on stainless usually indicate inadequate shielding or an inappropriate gas; a tri-mix (argon/helium/CO2 or argon/oxygen blends) with proper flow improves coverage and bead appearance. High CO2 and long stick-out worsen oxidation and shielding, and reducing flow is counterproductive.

Question 50GMAW (MIG) Welding Theory and Equipment Setup

On a GMAW power source, what does the voltage control primarily adjust?

  1. Inductance and pinch force
  2. Arc length and bead width Correct answer.
  3. Shielding gas flow rate
  4. Wire feed speed and deposition rate

Explanation

In constant-voltage GMAW, the voltage setting establishes the arc length, which in turn affects bead width and profile. Wire feed speed, not voltage, governs the current and deposition rate.