Practice Test Geeks(WCL) Welding Certification Los Angeles Practice Test
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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

  1. What is 'stress corrosion cracking' (SCC) and which condition promotes it?

    Answer: Cracking resulting from simultaneous tensile stress and a corrosive environment

    SCC requires the simultaneous presence of a susceptible material, tensile stress (residual or applied), and a specific corrosive environment to propagate.

  2. Why does welding austenitic stainless steel with high heat input increase risk of sensitization?

    Answer: High heat input keeps the metal in the sensitization temperature range longer

    Greater heat input extends time in the 800°F–1500°F sensitization range, giving more opportunity for chromium carbides to precipitate at grain boundaries.

  3. What is the primary advantage of using low-hydrogen (EXX18) electrodes when welding high-strength steel?

    Answer: They minimize diffusible hydrogen in the weld, reducing cold cracking risk

    Low-hydrogen electrodes have moisture-resistant coatings that limit diffusible hydrogen pickup in the weld metal, directly reducing hydrogen-induced cold cracking susceptibility.

  4. Which crystal structure do most common austenitic stainless steels (e.g., 304, 316) exhibit at room temperature?

    Answer: Face-centered cubic (FCC)

    Nickel stabilizes the austenite phase, which has an FCC crystal structure, in these stainless steels even at room temperature.

  5. What metallurgical problem can arise when welding aluminum alloys in the 6xxx series (e.g., 6061)?

    Answer: Loss of precipitation hardening strength in the HAZ

    Heat from welding dissolves the Mg2Si precipitates that provide 6xxx-series strength, overaging or annealing the HAZ and significantly reducing its mechanical properties.

  6. In the iron-carbon phase diagram, at what approximate carbon content does the eutectic reaction occur, producing cast iron microstructures?

    Answer: 4.3% C

    The iron-carbon eutectic point occurs at approximately 4.3% carbon and 2097°F (1147°C), where liquid iron solidifies into a mixture of austenite and cementite (ledeburite).

  7. What does 'Charpy impact testing' measure in welded joints?

    Answer: Absorbed energy during fracture, indicating toughness at specified temperatures

    The Charpy V-notch test measures the energy absorbed when a notched specimen is struck by a pendulum, quantifying toughness and ductile-to-brittle transition behavior.