Cold cracking occurs below what temperature?

Cold cracking occurs below what temperature?

• A. -50 C
• B. 0 C
• C. 150 C
• D. 300 C

Answer: (C)

Cold cracking is a hydrogen-assisted fracture that tends to occur in welded joints when there are residual or applied stresses and the metal is cooled to relatively low temperatures. Temperature plays a crucial role because it influences both the brittleness of the microstructure and how quickly hydrogen diffuses away from the weld region. In this item, the threshold given is 150 C, meaning that when the weld area experiences temperatures below this level while stresses are present, conditions become favorable for cracks to initiate and propagate. If the temperature stays above 150 C, the material generally remains more ductile and hydrogen diffusion is enhanced, reducing the likelihood of cracking. In practice, preventing cold cracking involves controlling hydrogen content in the weld metal, using proper preheating to keep temperatures above critical levels during welding, managing cooling rates, and minimizing restraint. Understanding this threshold helps inspectors assess the risk of cracking in welded joints under service conditions and determine appropriate mitigation measures.

Cold cracking is a hydrogen-assisted fracture that tends to occur in welded joints when there are residual or applied stresses and the metal is cooled to relatively low temperatures. Temperature plays a crucial role because it influences both the brittleness of the microstructure and how quickly hydrogen diffuses away from the weld region. In this item, the threshold given is 150 C, meaning that when the weld area experiences temperatures below this level while stresses are present, conditions become favorable for cracks to initiate and propagate. If the temperature stays above 150 C, the material generally remains more ductile and hydrogen diffusion is enhanced, reducing the likelihood of cracking. In practice, preventing cold cracking involves controlling hydrogen content in the weld metal, using proper preheating to keep temperatures above critical levels during welding, managing cooling rates, and minimizing restraint. Understanding this threshold helps inspectors assess the risk of cracking in welded joints under service conditions and determine appropriate mitigation measures.