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 welding metallurgy phenomenon causes the HAZ of certain stainless steels to become susceptible to intergranular corrosion?
Answer: Sensitization from chromium carbide precipitation
Sensitization occurs when chromium carbides precipitate at grain boundaries in the 425–870°C range, depleting adjacent areas of chromium and reducing corrosion resistance.
The liquidus temperature in a binary alloy phase diagram represents:
Answer: Temperature above which the alloy is completely liquid
The liquidus is the temperature above which the alloy exists entirely as liquid; below this line, solidification begins.
In welding metallurgy, 'dilution' refers to:
Answer: Reduction in weld metal properties due to base metal mixing
Dilution is the proportion of base metal melted into the weld pool, which changes the weld metal chemistry and can affect mechanical properties and corrosion resistance.
Which intermetallic phase in stainless steel welds severely embrittles the material at elevated service temperatures?
Answer: Sigma phase
Sigma phase, an iron-chromium intermetallic compound, forms between 600–900°C and causes severe embrittlement with near-zero impact toughness.
The Schaeffler diagram is used in welding to predict the microstructure of:
Answer: Stainless steel weld metal based on Cr and Ni equivalents
The Schaeffler (and WRC) diagram plots chromium equivalent vs. nickel equivalent to predict the ferrite, austenite, and martensite content of stainless steel weld deposits.
What is the purpose of the 'interpass temperature' limit during multi-pass welding?
Answer: Prevent overheating that degrades microstructure and mechanical properties
Limiting interpass temperature prevents excessive heat accumulation, which can coarsen grains, reduce toughness, and in some alloys cause sensitization or phase changes.
Which welding defect is directly caused by the contraction stresses exceeding the ductility of the weld metal during solidification?
Answer: Solidification cracking
Solidification cracking (hot cracking) occurs when tensile stresses during weld cooling and solidification exceed the ductility of the partially solidified weld metal.