Welding Metallurgy & Heat Treatment Flashcards
7 cards from real AWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Welding Metallurgy & Heat Treatment flashcards as text
What is 'lamellar tearing' and which base metal orientation makes it most susceptible?
Answer: Subsurface cracking due to inclusions; through-thickness (Z-direction) loading
Lamellar tearing is subsurface cracking that propagates along flattened non-metallic inclusions when through-thickness stresses act on steel with poor Z-direction ductility.
What effect does increasing heat input have on the HAZ grain size in carbon steel?
Answer: Promotes grain growth, reducing toughness
Higher heat input increases the peak temperature and time at temperature in the HAZ, promoting austenite grain growth which coarsens the final microstructure and reduces impact toughness.
When welding dissimilar metals, which major concern arises at the fusion boundary over time in high-temperature service?
Answer: Carbon migration from lower- to higher-alloy steel
In dissimilar welds (e.g., carbon steel to stainless steel), carbon migrates from the lower-alloy steel to the higher-alloy side at high temperatures, creating a decarburized zone and a carburized zone.
The 'critical cooling rate' in steel welding refers to:
Answer: Slowest cooling rate that still forms 100% martensite
The critical cooling rate is the minimum cooling rate required to suppress diffusion-controlled transformations and produce a fully martensitic microstructure.
Which test is most commonly used to determine the susceptibility of a steel to hydrogen-induced cold cracking after welding?
Answer: Implant test or Tekken (oblique Y-groove) test
The implant test and Tekken test apply controlled stress to a weld in a hydrogen-rich environment to measure the threshold stress for cold cracking.
What microstructural feature is most desirable in a structural weld metal to achieve high toughness?
Answer: Acicular ferrite
Acicular ferrite consists of fine, randomly oriented ferrite laths that nucleate on non-metallic inclusions, providing excellent strength and toughness by impeding crack propagation.
Solution annealing of austenitic stainless steel after welding is performed primarily to:
Answer: Re-dissolve chromium carbides and restore corrosion resistance
Solution annealing heats the steel to ~1040–1120°C to dissolve chromium carbides back into the austenite matrix, then rapidly quenches to prevent re-precipitation and restore corrosion resistance.