Welding Processes & Techniques Flashcards

After a hermetically sealed can is opened, which SMAW electrode must be kept in a heated holding oven to control moisture pickup?

Answer: E7018

E7018 is a low-hydrogen electrode whose coating absorbs moisture, so it must be stored in a holding oven (typically about 250°F minimum) to prevent hydrogen cracking.

Which GMAW metal transfer mode has the lowest heat input and is best suited for thin sheet and out-of-position welding?

Answer: Short-circuiting transfer

In short-circuiting transfer the wire touches the weld pool many times per second at low voltage and current, giving low heat input.

A field crew must weld structural steel outdoors in windy conditions with no wind screens. Which process is most suitable?

Answer: Self-shielded FCAW (FCAW-S)

FCAW-S makes its own shielding from the core ingredients, so wind does not blow away an external shielding gas.

In GTAW with direct current electrode negative (DCEN), roughly how much of the arc heat goes into the workpiece?

Answer: About two-thirds

With DCEN about two-thirds (roughly 70%) of the heat goes into the work, which gives deep penetration and keeps the tungsten cool.

Which arc welding process is normally limited to the flat and horizontal fillet positions because of its granular flux blanket?

Answer: Submerged arc welding

SAW uses loose granular flux that must lie over the joint, so it is generally restricted to flat and horizontal positions.

Which condition is needed to get axial spray transfer in GMAW of carbon steel?

Answer: Argon-rich shielding gas and current above the transition current

Spray transfer needs an argon-rich gas (usually at least about 80% Ar) and a current above the transition current for that wire size.

Electroslag welding is mainly used for which application?

Answer: Thick plates welded vertically in a single pass

ESW welds very thick sections in the vertical position in a single pass, but its high heat input can coarsen the HAZ grain.

An SMAW welder using DC sees the arc wander at the end of a joint because of arc blow. What is the most effective corrective action?

Answer: Switch to an AC power source

Arc blow comes from magnetic fields around DC current; AC reverses constantly and largely removes the effect.

In plasma arc welding, what does the keyhole technique do?

Answer: It lets the arc fully penetrate the joint, and the molten metal flows behind it

In keyhole PAW the constricted arc pierces the joint thickness and molten metal closes behind it, giving complete penetration in a single pass.

Which oxyacetylene flame is normally used to weld carbon steel?

Answer: Neutral flame

A neutral flame has roughly equal oxygen and acetylene, so it neither adds carbon to the steel nor oxidizes it.

What DC polarity is normally recommended for air carbon arc cutting (CAC-A) with standard DC copper-coated electrodes?

Answer: DCEP

Standard DC copper-coated carbon electrodes are used on DCEP for a stable arc and efficient metal removal.

An inspector reports undercut along the toes of fillet welds. What is the most likely cause?

Answer: Excessive current or travel speed

Too much current, travel speed, or arc length melts the base metal at the toe without enough filler to fill the groove.

In GMAW, how does a push (forehand) torch angle compare with a drag (backhand) angle?

Answer: Shallower penetration and a flatter, wider bead

Pushing aims the arc ahead onto cold metal, which gives a wider, flatter bead with less penetration than dragging.

A welder using a constant-voltage GMAW machine increases the contact-tip-to-work distance (stickout). What happens to the welding current?

Answer: It decreases

Longer stickout adds resistance heating in the wire, so a CV power source supplies less current.

What type of power source output is normally used for shielded metal arc welding?

Answer: Constant current (drooping)

SMAW uses a constant-current (drooping) power source so the current stays steady as the welder's arc length changes.

Why is E6010 often chosen for open-root passes on pipe?

Answer: Its high-cellulose sodium coating gives a forceful arc and deep penetration

The cellulosic coating of E6010 gives a digging arc with deep penetration and a light slag, which suits root passes in all positions.

In arc stud welding, what is the ceramic ferrule for?

Answer: It concentrates heat, shields the molten metal, and shapes the weld

The ferrule keeps in the arc heat, shields the molten pool, and forms the weld fillet, and it is broken off after welding.

What are the three primary variables in resistance spot welding?

Answer: Current, weld time, and electrode force

Spot weld heat follows I²Rt, so current, time, and electrode force (which affects contact resistance) are the key variables.

Why do WPSs for quenched and tempered steels often set a maximum interpass temperature?

Answer: To prevent HAZ softening and loss of toughness from too much heat input

Too much heat can over-temper Q&T steels, which lowers HAZ strength and toughness, so heat input and interpass temperature are limited.

What is a main advantage of pulsed GMAW over conventional spray transfer?

Answer: It gives spray-type transfer at a lower average current, so out-of-position welding is possible

Pulsing switches between a peak and a background current, giving spray-like droplet transfer at lower average heat input.