You're signing off a WPS and Google "low hydrogen welding prevents what failure mode" because the audit trail is thin. The procedure mandates baked E7018 electrodes and

Question

You're signing off a WPS and Google "low hydrogen welding prevents what failure mode" because the audit trail is thin. The procedure mandates baked E7018 electrodes and <5 ml/100 g diffusible hydrogen. The safeguard is followed, but the joint still fails 48 hours after welding. What hazard was never mitigated by the low‑hydrogen control in the first place?

Accepted Answer

A feels right because hydrogen cracking is the usual headline risk, but low‑hydrogen practice directly targets that mechanism, not ignores it. C tempts people who’ve seen overheated welds fail Charpy, yet grain growth isn’t addressed by hydrogen control at all — it’s heat input and time at temperature. D sounds subtle and very field‑real, but underbead cracking still needs hydrogen as the trigger. Solidification cracking happens while the weld pool freezes; diffusible hydrogen after solidification doesn’t touch segregation‑driven hot cracking, so B is the hole in the safeguard.

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