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 metallurgical difference between 'ferrite' and 'austenite' in steel?
Answer: Ferrite is BCC and magnetic; austenite is FCC and non-magnetic
Ferrite has a BCC crystal structure, is magnetic, and dissolves very little carbon; austenite is FCC, non-magnetic, and can dissolve significantly more carbon.
Which titanium alloy type is considered most weldable?
Answer: Commercially pure (CP) alpha titanium
Commercially pure titanium (alpha phase) is the most weldable because it does not undergo the complex phase transformations that can embrittle alpha-beta and beta alloys during welding.
When welding dissimilar metals with widely different coefficients of thermal expansion, which weld defect is most likely?
Answer: Cracking or delamination due to differential thermal stresses
Mismatched thermal expansion causes differential contraction on cooling, generating residual stresses that can crack the joint or delaminate the bond at the fusion interface.
What is 'weld dilution' and why does it matter when selecting filler metal?
Answer: The mixing of base metal into the weld pool, changing the deposit's composition
Dilution is the percentage of base metal that melts into the weld pool; high dilution can alter the chemical composition of the deposit away from the filler metal's nominal analysis, affecting corrosion resistance or strength.
Which heat treatment process is used to remove brittleness from hardened steel by heating below the lower critical temperature?
Answer: Tempering
Tempering heats hardened steel to a sub-critical temperature (typically 300°F–1300°F), relieving internal stresses and reducing brittleness while retaining useful hardness.
What type of corrosion occurs when two dissimilar metals are electrically connected in the presence of an electrolyte?
Answer: Galvanic corrosion
Galvanic corrosion occurs when two metals with different electrochemical potentials are coupled in an electrolyte, accelerating corrosion of the more anodic (less noble) metal.
In dual-phase (DP) advanced high-strength steel, which two microstructural phases are typically present?
Answer: Ferrite and martensite
Dual-phase steels consist of a soft ferrite matrix with islands of hard martensite, combining good formability with high tensile strength—a combination important in automotive structural welding.