Metallurgy & Material Science Flashcards
7 cards from real WCL 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 & Material Science flashcards as text
What is the primary reason carbon content is limited in structural steel used for welding applications?
Answer: Higher carbon increases brittleness and cold cracking risk
Elevated carbon content raises hardenability and increases susceptibility to hydrogen-induced cold cracking in the heat-affected zone.
Which phase transformation occurs when austenite is rapidly quenched and results in a hard, brittle microstructure?
Answer: Martensite formation
Rapid quenching traps carbon in a body-centered tetragonal lattice, forming martensite—the hardest and most brittle steel microstructure.
What does the term 'preheat' accomplish metallurgically in high-carbon steel welding?
Answer: It slows the cooling rate to reduce martensite formation
Preheat raises the base metal temperature, slowing post-weld cooling and reducing the likelihood of martensite formation in the HAZ.
Which alloying element in stainless steel is primarily responsible for corrosion resistance?
Answer: Chromium
Chromium (minimum ~10.5%) forms a passive chromium oxide film on the surface that protects stainless steel from oxidation and corrosion.
What is 'sensitization' in austenitic stainless steel and when does it occur?
Answer: Chromium carbide precipitation at grain boundaries between 800°F–1500°F
Sensitization occurs when chromium carbides precipitate at grain boundaries, depleting adjacent zones of chromium and making them susceptible to intergranular corrosion.
A welder is joining 4140 alloy steel. Which element in this steel most significantly raises its carbon equivalent (CE)?
Answer: Chromium
Chromium has a high CE contribution factor; in 4140 steel it is present at ~0.8–1.1% and substantially raises the overall carbon equivalent.
What microstructural feature makes cast iron extremely difficult to weld without special procedures?
Answer: Very high carbon content forming brittle martensite or white iron in the HAZ
Cast iron's high carbon content (2–4%) promotes formation of extremely hard, brittle white iron or martensite in the rapidly cooled heat-affected zone.