AWS Weld Metallurgy & Heat Treatment Flashcards
6 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 6 AWS Weld Metallurgy & Heat Treatment flashcards as text
The primary purpose of preheating before welding is to:
Answer: Reduce the risk of hydrogen-induced cracking by slowing the cooling rate
Preheat slows the cooling rate of the weld and HAZ, allowing hydrogen to diffuse out and reducing the risk of hydrogen-induced cracking and martensitic transformation.
The minimum preheat temperature for a given steel is primarily determined by:
Answer: The carbon equivalent and thickness of the base metal
Minimum preheat temperature is determined by the carbon equivalent (CE) of the steel and the section thickness, as specified in codes like AWS D1.1.
Interpass temperature refers to:
Answer: The maximum temperature of the weld zone between successive weld passes
Interpass temperature is the temperature of the weld zone immediately before depositing the next pass, and has a maximum limit to prevent degradation of mechanical properties.
Post-weld heat treatment (PWHT) is primarily used to:
Answer: Relieve residual stresses and temper hard microstructures
PWHT reduces residual stresses from welding, tempers hard martensitic structures, and improves toughness and dimensional stability.
For carbon steel, a typical stress relief PWHT temperature range is:
Answer: 1000–1200°F (538–649°C)
Carbon and low-alloy steels are typically stress relieved at 1000–1200°F (538–649°C), which is below the lower critical transformation temperature.
Hydrogen bake-out is a procedure performed to:
Answer: Diffuse hydrogen out of the weld by holding at a moderately elevated temperature
Hydrogen bake-out involves heating the weld to 200–400°F (93–204°C) and holding it to accelerate hydrogen diffusion out of the weld metal before cracking can occur.