Which outcome occurs when a welding arc causes rapid local melting in steel undergoing a phase transition?

💡 Explanation

When rapid local melting happens in steel during welding, quenching occurs around the weld as the metal cools quickly after exceeding the austenite phase transition temperature. This mechanism causes a diffusionless transformation, resulting in the formation of hard, brittle martensite because carbon atoms are trapped. Therefore martensite forms, rather than ferrite grain growth or resistance to hydrogen embrittlement which require slow cooling or tempered phases.

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