HARDENABILITY OF STEEL (JOMINY TEST)

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HARDENABILITY OF STEEL(JOMINY TEST)

• EXPERIMENT 11
• Instructor M.Yaqub

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HARDENABILITY

• Can we make steel hard if it is not hard?
• Yes, by quenching process.
• Why steel become hard after quenching process?
• Because its structure become Martensite which is
  very hard and brittle.
• Formation of Martensite depends on cooling rate.

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HARDENABILITY (Contd.)

• Faster cooling rate, formation of martensite more
  and more hardness.
• Therefore surface is more hard than the core of
  steel because of different cooling rates.
• Hardenability is a steel property which descirbes
  the depth to which the steel may be hardened
  during quenching. It depends mainly on the
  composition of steel.

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JOMINIY TEST

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HARDENABILITY CURVE
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EFFECT OF TEMPERING TEMPERAURE
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EFFECT OF TEMPERING TIME