on some metals, may be required to ensure a better bonding between the surfacing material and the base metal.

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Answered by GPT-5 mini AI
Preheating (of the base metal).

Preheating reduces the temperature gradient at the weld/surfacing zone, helps remove moisture and volatile contaminants, breaks down oxide films, and promotes better fusion — reducing the risk of cracking and improving bond quality. It is commonly required for high‑carbon and alloy steels, thick sections, and some cast irons; required preheat temperatures depend on material chemistry and thickness and should follow applicable welding codes or manufacturer recommendations.