Welding & Fabrication Flashcards

Which welding process uses a consumable electrode covered with a flux coating?

Answer: SMAW (Stick welding)

SMAW (Shielded Metal Arc Welding) uses a flux-coated stick electrode that melts to shield the weld pool from atmospheric contamination.

What is the primary purpose of preheating steel before welding?

Answer: To reduce the risk of hydrogen-induced cracking

Preheating slows the cooling rate and allows hydrogen to diffuse out of the weld zone, preventing hydrogen-induced (cold) cracking.

Which shielding gas is standard for GTAW (TIG) welding of stainless steel?

Answer: 100% Argon

Pure argon is the standard shielding gas for TIG welding stainless steel because it is inert and provides excellent arc stability without oxidizing the material.

What does 'duty cycle' mean when referring to welding equipment?

Answer: The percentage of a 10-minute period a machine can weld at a rated output without overheating

Duty cycle is the percentage of a 10-minute period that a welding machine can continuously operate at a given output level before it must cool down.

Which weld defect is a groove melted into the base metal along the toe of the weld that is left unfilled by weld metal?

Answer: Undercut

Undercut is a groove eroded into the base metal along the weld toe, reducing the effective cross-sectional area and creating a stress concentration.

What is the purpose of back purging with argon when TIG welding stainless steel pipe?

Answer: To prevent oxidation on the inside (root) surface of the weld

Back purging introduces argon to the pipe interior to exclude oxygen, preventing oxidation ('sugaring') on the root surface that would compromise corrosion resistance.

What is the correct polarity when welding with an E7018 low-hydrogen electrode?

Answer: DCEP (Direct Current Electrode Positive)

E7018 electrodes require DCEP (reverse polarity), which concentrates heat at the electrode tip for proper flux melting and provides a stable, smooth arc.

In the electrode designation E7018, what does the number '70' represent?

Answer: Minimum tensile strength of the deposited weld metal in ksi

The digits '70' in E7018 indicate a minimum tensile strength of 70,000 psi (70 ksi) for the weld deposit in the as-welded condition.

What type of oxy-acetylene flame is used when welding cast iron?

Answer: Carburizing (reducing) flame

A slightly carburizing flame is used for cast iron to add carbon to the weld zone and compensate for carbon burn-off during the welding process.

What does FCAW stand for?

Answer: Flux-Cored Arc Welding

FCAW stands for Flux-Cored Arc Welding, which uses a tubular wire electrode with a flux-filled core to shield and protect the weld pool.

What is the primary purpose of a backing bar (backing strip) placed behind a weld joint?

Answer: To support the molten weld pool and ensure full root penetration on single-sided welds

A backing bar supports the molten root pass from below, allowing full-penetration welds to be made from one side without burn-through.

What causes porosity in a completed weld?

Answer: Gas entrapped in the solidifying weld metal forming voids

Porosity occurs when gases such as hydrogen, nitrogen, or oxygen become trapped in the solidifying weld pool before they can escape, forming voids or bubbles.

What travel angle is typically used with a drag technique during flat-position SMAW welding?

Answer: 10–15° from vertical in the direction of travel

A 10–15° drag (travel) angle directs arc force slightly forward into the joint, improving penetration and bead shape in the flat position.

Which weld joint configuration is formed when two pieces of metal are aligned end to end in the same plane?

Answer: Butt joint

A butt joint is created when two pieces of metal are placed edge to edge in the same plane and welded along their abutting edges.

In the electrode classification E7018, what does the last digit '8' indicate?

Answer: The coating type and compatible current/polarity

The last digit of an SMAW electrode classification designates the flux coating composition and specifies which current types and polarities are compatible.

Which NDT method magnetizes ferromagnetic components and uses iron particles to reveal surface and near-surface discontinuities?

Answer: Magnetic particle testing (MT)

Magnetic particle testing (MT) induces a magnetic field in ferromagnetic material; particles accumulate at flux leakage points caused by surface or near-surface defects.

What is the purpose of a weld test coupon?

Answer: To qualify a welding procedure or certify a welder's proficiency

A weld coupon is a test piece used to qualify Welding Procedure Specifications (WPS) or to certify welders by evaluating weld quality and mechanical properties.

What is the primary advantage of GTAW (TIG welding) compared to GMAW (MIG welding)?

Answer: Superior weld quality and precise control, especially on thin materials and reactive alloys

GTAW provides a cleaner, more controllable arc with no spatter and independent control of heat and filler metal, making it ideal for thin sections, stainless steel, and aluminum.

What are the primary goals of post-weld heat treatment (PWHT)?

Answer: To relieve residual stresses and improve heat-affected zone toughness

PWHT heats the welded assembly to a specified temperature and holds it there to reduce residual stresses, temper hard microstructures, and improve toughness and corrosion resistance.

What is weld distortion, and which technique is commonly used to minimize it?

Answer: Dimensional change from non-uniform heating and cooling; minimized by tacking, clamping, or back-step welding

Weld distortion is dimensional change caused by differential thermal expansion and contraction; it is controlled by pre-setting, clamping fixtures, balanced weld sequences, or back-step welding.