Forge Welding Temperature Calculator

Forge welding requires both pieces to reach a near-liquid, sparking surface state at the same time, but pushing the more heat-tolerant steel to its own ideal temperature can burn or overheat the more sensitive partner before it's even done catching up. Using the lower value keeps the weaker steel safe, even though it means the tougher steel is welded slightly below its own optimal point — that's the standard practical compromise smiths use for dissimilar-steel pairings, and it's why the calculator never averages the two temperatures.

Plain borax struggles to dissolve the tenacious chromium oxide layer that forms on stainless steel at welding heat, so leaving any borax-only recommendation in place for a stainless pairing would likely produce a failed or inclusion-riddled weld. The calculator checks whether either selected steel is the stainless option and, if so, always switches to a fluoride-based flux (like Anti-Borax or Cherry Heat) regardless of what the other steel in the pair is.

No — Ambient Temperature only feeds into the Est. Heat-Up Time estimate (roughly 15 minutes minus a small adjustment for how far the air is above or below freezing, floored at 5 minutes), not into the Welding Temperature figure itself. The target weld temperature is determined entirely by which two steels you select; a cold shop just means your stock takes a little longer to get there, not that you should weld at a lower heat.

When steel1Type and steel2Type match, there's no temperature compromise to manage and no carbon-migration risk across dissimilar compositions, so the calculator labels it a same-steel weld and rates it as the most forgiving case. Mixed carbon-content pairings step up to 'Moderate' because carbon can migrate across the weld line during heating, and any pairing involving stainless is flagged 'Very Difficult' since it demands more precise heat control and specialized flux to succeed.