CWI Fundamentals Tech 5 — Questions and Answers
Question 1: Which type of weld discontinuity is described as a groove melted into the base metal adjacent to the weld toe?
- Overlap
- Undercut (Correct answer)
- Underfill
- Porosity
Correct answer: Undercut
Undercut is a groove or channel melted into the base metal at the weld toe, reducing the effective throat and creating a stress concentration.
Question 2: What is the significance of the 'A number' classification in AWS filler metal standards?
- Indicates amperage range for the electrode
- Classifies deposited weld metal chemical composition (Correct answer)
- Specifies the electrode aspect ratio
- Denotes the flux activity level
Correct answer: Classifies deposited weld metal chemical composition
The A-number system classifies deposited weld metal according to chemical composition, primarily used for stainless steel and alloy filler metals.
Question 3: During visual inspection, a CWI finds a crater crack at the end of a weld. What is the most likely cause?
- Excessive preheat applied before welding
- Improper termination of the arc without filling the crater (Correct answer)
- Too slow a travel speed at weld termination
- Insufficient amperage throughout the weld pass
Correct answer: Improper termination of the arc without filling the crater
Crater cracks form when the arc is extinguished abruptly, leaving an unfilled, rapidly cooling crater that cracks as it shrinks.
Question 4: Which AWS electrode classification represents a low-hydrogen SMAW electrode?
- E6010
- E6013
- E7018 (Correct answer)
- E6011
Correct answer: E7018
E7018 is a low-hydrogen electrode (indicated by the '8' suffix), requiring controlled storage to prevent moisture absorption.
Question 5: What is the function of the flux coating on an SMAW electrode?
- To increase electrical conductivity of the electrode
- To provide shielding gas, deoxidizers, and slag for weld protection (Correct answer)
- To reduce the melting point of the filler metal
- To color-code the electrode for identification only
Correct answer: To provide shielding gas, deoxidizers, and slag for weld protection
The flux coating generates shielding gases to protect the molten weld pool, provides deoxidizers, and forms a slag blanket that protects the solidifying weld.
Question 6: When checking a fillet weld with a fillet weld gauge, what dimension is being verified?
- Weld bead length
- Leg size and throat dimension (Correct answer)
- Travel speed compliance
- Interpass temperature
Correct answer: Leg size and throat dimension
A fillet weld gauge measures the leg size and can also be used to estimate the theoretical throat of a fillet weld.
Question 7: Which of the following is an example of a 'planar' weld discontinuity?
- Porosity
- Tungsten inclusion
- Lack of fusion (Correct answer)
- Slag inclusion
Correct answer: Lack of fusion
Lack of fusion is a planar discontinuity because it lies in a plane — the unfused interface between weld metal and base metal — making it most severe under loading.
CWI Fundamentals Tech 5
Which type of weld discontinuity is described as a groove melted into the base metal adjacent to the weld toe?