NL Welder Certification Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. Which welding process uses a consumable electrode coated with
flux?
a) GTAW
b) SMAW
c) GMAW
d) FCAW
Answer: b) SMAW
This process, Shielded Metal Arc Welding, uses a consumable electrode
covered with flux to protect the weld from contamination.
2. What is the primary purpose of preheating a metal before welding?
a) To increase welding speed
b) To reduce welding defects
c) To make the metal softer
d) To eliminate the need for filler metal
Answer: b) To reduce welding defects
Preheating helps reduce thermal shock, cracking, and distortion in the
weld area.
3. In welding, what does the term “slag” refer to?
a) Unfused metal
b) The molten weld pool
,c) A layer of flux residue
d) A welding defect
Answer: c) A layer of flux residue
Slag forms from flux decomposition and protects the weld while cooling.
4. Which welding process is also known as “MIG” welding?
a) GMAW
b) GTAW
c) SMAW
d) FCAW
Answer: a) GMAW
Gas Metal Arc Welding (GMAW) is commonly called MIG welding.
5. What is the main shielding gas used in GTAW for carbon steel?
a) Argon
b) Oxygen
c) Nitrogen
d) Helium
Answer: a) Argon
Argon provides an inert atmosphere to prevent oxidation during GTAW.
6. What is the correct angle for a fillet weld in the flat position?
a) 30°
b) 45°
c) 60°
d) 90°
Answer: b) 45°
A 45° angle ensures proper penetration and bead shape in a fillet weld.
, 7. Which welding defect is characterized by localized depressions
along the weld?
a) Porosity
b) Undercut
c) Overlap
d) Crater
Answer: b) Undercut
Undercut occurs when the base metal is melted away along the edges,
weakening the joint.
8. What is the recommended electrode angle for vertical-up SMAW
welding?
a) 0–10°
b) 15–30°
c) 45–60°
d) 75–90°
Answer: b) 15–30°
This angle ensures proper penetration and bead control in vertical-up
welding.
9. Which filler metal is commonly used for welding stainless steel?
a) ER70S-6
b) E308L-16
c) E7018
d) ER4043
Answer: b) E308L-16
This low-carbon stainless steel electrode prevents carbide precipitation
and corrosion.
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. Which welding process uses a consumable electrode coated with
flux?
a) GTAW
b) SMAW
c) GMAW
d) FCAW
Answer: b) SMAW
This process, Shielded Metal Arc Welding, uses a consumable electrode
covered with flux to protect the weld from contamination.
2. What is the primary purpose of preheating a metal before welding?
a) To increase welding speed
b) To reduce welding defects
c) To make the metal softer
d) To eliminate the need for filler metal
Answer: b) To reduce welding defects
Preheating helps reduce thermal shock, cracking, and distortion in the
weld area.
3. In welding, what does the term “slag” refer to?
a) Unfused metal
b) The molten weld pool
,c) A layer of flux residue
d) A welding defect
Answer: c) A layer of flux residue
Slag forms from flux decomposition and protects the weld while cooling.
4. Which welding process is also known as “MIG” welding?
a) GMAW
b) GTAW
c) SMAW
d) FCAW
Answer: a) GMAW
Gas Metal Arc Welding (GMAW) is commonly called MIG welding.
5. What is the main shielding gas used in GTAW for carbon steel?
a) Argon
b) Oxygen
c) Nitrogen
d) Helium
Answer: a) Argon
Argon provides an inert atmosphere to prevent oxidation during GTAW.
6. What is the correct angle for a fillet weld in the flat position?
a) 30°
b) 45°
c) 60°
d) 90°
Answer: b) 45°
A 45° angle ensures proper penetration and bead shape in a fillet weld.
, 7. Which welding defect is characterized by localized depressions
along the weld?
a) Porosity
b) Undercut
c) Overlap
d) Crater
Answer: b) Undercut
Undercut occurs when the base metal is melted away along the edges,
weakening the joint.
8. What is the recommended electrode angle for vertical-up SMAW
welding?
a) 0–10°
b) 15–30°
c) 45–60°
d) 75–90°
Answer: b) 15–30°
This angle ensures proper penetration and bead control in vertical-up
welding.
9. Which filler metal is commonly used for welding stainless steel?
a) ER70S-6
b) E308L-16
c) E7018
d) ER4043
Answer: b) E308L-16
This low-carbon stainless steel electrode prevents carbide precipitation
and corrosion.
