Metallurgy and Weld Discontinuities Flashcards
7 cards from real CWI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Metallurgy and Weld Discontinuities flashcards as text
Which weld discontinuity is caused by the base metal melting away beneath the weld toe, creating a groove along the weld edge?
Answer: Undercut
Undercut is a groove melted into the base metal at the weld toe that remains unfilled by weld metal, reducing the effective cross-section.
In welding metallurgy, what does the term 'HAZ' refer to?
Answer: Heat-Affected Zone
HAZ stands for Heat-Affected Zone, the region of base metal adjacent to the weld that has had its microstructure altered by welding heat without melting.
Which type of crack forms along the centerline of a weld bead due to solidification shrinkage and low-melting-point segregates?
Answer: Centerline solidification crack
Centerline solidification cracks occur along the weld centerline as the last liquid to solidify contains low-melting-point impurities that cannot withstand shrinkage stresses.
What is the primary cause of porosity in a weld?
Answer: Gas entrapment during solidification
Porosity results from gas being trapped in solidifying weld metal, commonly caused by moisture, contamination, or inadequate shielding gas coverage.
Which discontinuity occurs when weld metal flows over the base metal surface without fusing to it?
Answer: Overlap
Overlap (cold lap) occurs when molten weld metal flows over the base metal surface but fails to fuse with it, creating a sharp notch.
In carbon steel, what phase transformation occurs when steel is rapidly cooled (quenched) from the austenite region?
Answer: Martensite formation
Rapid quenching of austenite produces martensite, a hard and brittle body-centered tetragonal (BCT) crystal structure that forms without diffusion.
A weld inspector finds a discontinuity classified as 'incomplete joint penetration' (IJP). What does this mean?
Answer: The weld metal did not fully penetrate to the root of the joint
Incomplete joint penetration means the weld metal failed to extend through the full thickness of the joint to the root, leaving an unfused area at the root.