CWI Fundamentals 2 — Questions and Answers
Question 1: Which welding process uses a non-consumable tungsten electrode and a separate filler metal?
- GMAW
- SMAW
- GTAW (Correct answer)
- FCAW
Correct answer: GTAW
GTAW (Gas Tungsten Arc Welding) uses a non-consumable tungsten electrode; filler metal is added separately if needed.
Question 2: What does the term 'heat-affected zone' (HAZ) refer to in welding?
- The molten weld pool during welding
- The base metal area altered by heat but not melted (Correct answer)
- The flux coating on a SMAW electrode
- The shielding gas envelope around the arc
Correct answer: The base metal area altered by heat but not melted
The HAZ is the portion of the base metal whose properties have been altered by welding heat without actually melting.
Question 3: A CWI discovers a crack running along the centerline of a weld bead. This defect is most likely caused by:
- Excessive preheat temperature
- High sulfur or phosphorus content in the base metal (Correct answer)
- Insufficient arc voltage
- Excessive shielding gas flow rate
Correct answer: High sulfur or phosphorus content in the base metal
Centerline (hot) cracking is commonly caused by low-melting-point impurities such as sulfur and phosphorus segregating at the weld centerline.
Question 4: According to AWS D1.1, what is the minimum preheat temperature for welding 1-inch thick ASTM A36 steel when the ambient temperature is above 32°F?
- No preheat required (Correct answer)
- 150°F (65°C)
- 200°F (93°C)
- 300°F (149°C)
Correct answer: No preheat required
AWS D1.1 Table 4.5 requires no minimum preheat for A36 steel up to 1.5 inches thick when temperature is above 32°F.
Question 5: Which discontinuity is characterized by fusion that does not extend to the full cross-section of the joint as specified?
- Porosity
- Incomplete joint penetration (Correct answer)
- Undercut
- Overlap
Correct answer: Incomplete joint penetration
Incomplete joint penetration occurs when the weld metal fails to extend through the full thickness specified in the design.
Question 6: What is the purpose of a preheat when welding high-carbon or alloy steels?
- Increase travel speed
- Reduce the risk of hydrogen-induced cracking (Correct answer)
- Increase penetration depth
- Remove mill scale before welding
Correct answer: Reduce the risk of hydrogen-induced cracking
Preheat slows the cooling rate of the HAZ, allowing hydrogen to diffuse out and reducing the risk of cold (hydrogen-induced) cracking.
Question 7: When visually inspecting a completed groove weld, the inspector should verify the weld face reinforcement does NOT exceed:
- 1/16 inch for all thicknesses
- 3/16 inch regardless of plate thickness
- The limit specified in the applicable code or standard (Correct answer)
- 1/4 inch for plates thicker than 1 inch
Correct answer: The limit specified in the applicable code or standard
Acceptable reinforcement limits vary by code; the inspector must always apply the limit stated in the governing code or engineering document.
CWI Fundamentals 2
Which welding process uses a non-consumable tungsten electrode and a separate filler metal?