Which primary risk arises during multi-pass welding of thick structural steel sections?

💡 Explanation

During multi-pass welding, hydrogen diffusion occurs because moisture decomposes in the arc, and atomic hydrogen dissolves into the molten weld pool, potentially leading to hydrogen-induced cracking in the heat-affected zone. Therefore, hydrogen-induced cracking is the primary HAZ risk, rather than copper embrittlement, excessive grain growth or arc blow, which involve different contaminants or welding conditions.

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