What is a cold weld, and how might it be identified in testing?

What is a cold weld, and how might it be identified in testing?

• A. A weld with inadequate fusion due to insufficient heat; indicated by lack of fusion on radiography/UT or poor penetration.
• B. A weld made at very low ambient temperature but with perfect fusion.
• C. A weld with excessive fusion causing distortion; indicated by radiography showing excess penetrations.
• D. A weld that has high ductility; indicated by bend test passing.

Answer: (A)

Cold welding is when heat input is too low to achieve proper fusion between the weld metal and the base metal. The joint may look welded, but the metal hasn’t actually fused, leaving a weak bond. In testing, you’d expect signs of lack of fusion or poor penetration. Radiography can show gaps or missing fusion at the weld-to-base metal boundary, while ultrasonic testing can reveal incomplete bonding along the fusion line. This is why the correct description focuses on inadequate fusion due to insufficient heat and the corresponding NDT indicators. The other scenarios don’t fit: welding at a low ambient temperature with perfect fusion isn’t a cold weld, excessive fusion that causes distortion isn’t the issue, and high ductility detected by a bend test doesn’t define a cold weld.

Cold welding is when heat input is too low to achieve proper fusion between the weld metal and the base metal. The joint may look welded, but the metal hasn’t actually fused, leaving a weak bond. In testing, you’d expect signs of lack of fusion or poor penetration. Radiography can show gaps or missing fusion at the weld-to-base metal boundary, while ultrasonic testing can reveal incomplete bonding along the fusion line. This is why the correct description focuses on inadequate fusion due to insufficient heat and the corresponding NDT indicators. The other scenarios don’t fit: welding at a low ambient temperature with perfect fusion isn’t a cold weld, excessive fusion that causes distortion isn’t the issue, and high ductility detected by a bend test doesn’t define a cold weld.