Q
Heat hardening is the process done at_______________?
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A
A. Heating 750°c and slowly cooling to zero degree
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B
B. Heating quickly upto 450°c followed by sudden quenching
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C
C. Heating upto 250°c for 15 to 30 min
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D
D. Heating at 750°c and then quenching to room temperature
Correct Answer:
C. C. Heating upto 250°c for 15 to 30 min