Forge Weld Won’t Stick
Symptom
Layers separate at the seam when drawing, a welded billet opens like a book at the first hard blows, a tomahawk eye wrap pops its tongue weld, or grinding reveals a bright hairline where two pieces never actually joined.
Likely Causes
Scale trapped in the joint (the number-one cause — steel welded to its own oxide, not to steel). Welding heat never actually reached — the surface sparkled but the core sat dark. Dirty mating faces: grinder dust, oil, old flux glass. Flux applied too late, after scale already formed. Blows too soft or too slow, letting the joint cool between hits. Joint geometry that traps air — flat-on-flat with no scarf crown for the weld to sweep outward from. High-alloy or stainless material in the stack that resists welding entirely (see the steel database — chromium raises welding difficulty fast).
Quick Checks
Grind into the failed seam: bright clean steel both sides means a cold or scaled weld, gray glassy inclusions mean trapped flux. Check your stack prep: were mating faces ground clean and flat that session? Watch the next attempt’s color in shade — true welding heat is bright yellow trending white, and the surface goes wet-slick and tacky. Count seconds between anvil arrival and first blow: more than about two and the surface has already cooled and scaled.
Fixes
Cut or grind back to sound material past every trace of the failed seam — a re-weld over trapped scale fails twice. Re-scarf with crowned faces so the weld sweeps air and flux outward. Clean to bright steel, flux early (before visible scale forms, around orange heat) unless running a deliberate dry-flux practice with a reducing fire. Take a genuine soak at welding heat — the core must arrive, not just the skin — then weld off the anvil-arrival instant: firm fast overlapping blows from the center of the joint outward. Reset the fire if it is oxidizing: a slightly rich, stable fire is half the weld. Full sequence in the damascus section and the wrapped-eye walkthrough in Forging a Tomahawk.
Prevention
Prep every weld like it matters: bright faces, early flux, crowned scarfs, a settled fire. Work at the front of the heat, never the tail. Practice on mild steel until the wet-look and the timing are reflexes — mild forgives, blade steel does not. For eye wraps, tack the tongues aligned before the full weld so nothing shifts at heat.
When to Stop and Get Help
If a billet has opened twice in the same seam, stop welding on it — cut the seam out entirely and rebuild the stack; chasing a contaminated weld wastes heats and steel. And if welds consistently fail across different projects, the fire itself is the suspect: fix the burner or fuel before blaming your hammer.