Question:
Preheating of Base metal during welding is required to
Preheating of Base metal during welding is required to
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Preheating = Slower Cooling. Slower cooling prevents the metal from becoming glass-brittle and cracking.
Updated On: Jul 4, 2026
- Reduce heat input
- Increase heat input
- Increase cooling rate
- Decreases cooling rate
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The Correct Option is D
Solution and Explanation
Step 1: Concept Welding involves localized heating followed by rapid cooling as heat is conducted away by the surrounding base metal.
Step 2: Meaning Rapid cooling can lead to the formation of brittle phases like martensite or cause thermal cracking (hydrogen cracking).
Step 3: Analysis By warming the entire base metal (preheating) before welding, the temperature gradient between the weld and the surrounding area is reduced.
Step 4: Conclusion This smaller gradient slows down the conduction of heat away from the weld, thereby decreasing the cooling rate. Final Answer: (D)
Step 2: Meaning Rapid cooling can lead to the formation of brittle phases like martensite or cause thermal cracking (hydrogen cracking).
Step 3: Analysis By warming the entire base metal (preheating) before welding, the temperature gradient between the weld and the surrounding area is reduced.
Step 4: Conclusion This smaller gradient slows down the conduction of heat away from the weld, thereby decreasing the cooling rate. Final Answer: (D)
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