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 element is most commonly responsible for increasing hardenability in low-alloy steels?
Answer: Manganese
Manganese is the most effective common alloying element for increasing hardenability, allowing martensite to form at slower cooling rates.
What type of discontinuity results from entrapped non-metallic material (such as flux) within a completed weld?
Answer: Slag inclusion
Slag inclusions are non-metallic solid materials entrapped in weld metal or between weld metal and base metal, often caused by improper inter-pass cleaning.
Hydrogen-induced cracking (HIC) in welds is also commonly known as:
Answer: Cold cracking
Hydrogen-induced cracking is called cold cracking because it occurs at or near room temperature after welding is complete, unlike hot cracks which form during solidification.
The carbon equivalent (CE) formula is used by CWI inspectors primarily to assess:
Answer: Risk of hydrogen-induced cracking (cold cracking)
The carbon equivalent formula estimates a steel's susceptibility to hydrogen-induced cold cracking by accounting for the hardenability effect of alloying elements.
Which weld discontinuity is described as a depression or groove in the weld face that goes below the surface of the adjacent base metal?
Answer: Underfill
Underfill is a condition where the weld face or root surface is below the adjacent base metal surface due to insufficient weld metal deposition.
What is the primary purpose of applying preheat before welding?
Answer: To slow the cooling rate and reduce risk of cold cracking
Preheat slows the cooling rate of the weld and HAZ, reducing thermal gradients, minimizing martensite formation, and allowing hydrogen to diffuse out.
In weld inspection terminology, what is a 'lamellar tear'?
Answer: A subsurface planar crack in base metal caused by through-thickness shrinkage strains
Lamellar tearing is a subsurface cracking phenomenon in rolled steel plate caused by through-thickness tensile stresses acting on low-ductility inclusions, typically sulfide inclusions.