P3. It is desired to begin with a eutectoid steel, it is desirous to reach a...

P3. It is desired to begin with a eutectoid steel, it is desirous to reach a combination

(a) 680 HB and ~0%RA

(b) 260 HB and 20%RA; , please recommend material and treatment preferably with given composition if not suggest alternative. Explain the use of TTT/Phase diagram and combination of phases

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Part A

Refer to above figures a martensitic material has a percentage of 0.6% at a hardness of 680.
From we see that a martensitic material must have a cooling rate of at least 140° C/s.

Part B

Refer to Figure We see that only fine pearlite has a hardness of at least 260 at 0.7%. C.
However a 20%. RA for fine pearlite requires 0.75%. From Figure we see that a fine pearlite must have a cooling rate less than 35° C/s

samet mamat answered 1 year ago

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