To minimize crater cracking at the end of a weld, what technique is recommended?

To minimize crater cracking at the end of a weld, what technique is recommended?

• A. Finish with crater fill or a short ramp and gradually stopping.
• B. Stop abruptly.
• C. Quench the weld with water.
• D. Increase current at end.

Answer: (A)

Finish with crater fill or end with a short ramp and gradually stop. This technique reduces crater cracking by smoothing out the end of the weld, where a hot, still-solidifying crater can trap residual stresses. Filling the crater or easing out of the weld allows a more gradual cooling and solidification, lowering the stress concentration at the end and preventing cracks from forming as the weld cools. Stopping abruptly creates a sharp boundary in the last portion of weld metal, leading to high tensile stresses as it contracts, which promotes cracking. Quenching with water causes very rapid cooling and distortion, and can also worsen cracking tendencies by introducing unexpected thermal shocks. Increasing current at the end adds heat instead of easing it, which can enlarge the crater and increase residual stresses instead of mitigating them.

Finish with crater fill or end with a short ramp and gradually stop. This technique reduces crater cracking by smoothing out the end of the weld, where a hot, still-solidifying crater can trap residual stresses. Filling the crater or easing out of the weld allows a more gradual cooling and solidification, lowering the stress concentration at the end and preventing cracks from forming as the weld cools.

Stopping abruptly creates a sharp boundary in the last portion of weld metal, leading to high tensile stresses as it contracts, which promotes cracking. Quenching with water causes very rapid cooling and distortion, and can also worsen cracking tendencies by introducing unexpected thermal shocks. Increasing current at the end adds heat instead of easing it, which can enlarge the crater and increase residual stresses instead of mitigating them.