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Purposes of heat treatment

Short answer

Heat treatment aims to alter mechanical properties: it can increase hardness, soften metal, improve strength and toughness, relieve stresses, refine grain, and enhance ductility. It also enables surface hardening and improves electrical or magnetic characteristics.

What are the purposes (objectives) of heat treatment of metal?

The main purposes of heat treatment of metals (steel) are:

  1. To increase hardness and wear resistance (for example cutting tools and bearing surfaces) by quenching.
  2. To soften the metal and improve machinability and cold working (annealing).
  3. To improve strength and toughness, and to obtain a good combination of them (normalizing, tempering).
  4. To relieve internal stresses caused by welding, casting, forging or cold working, preventing cracking and distortion.
  5. To refine the grain size and make the structure uniform (homogeneous).
  6. To increase ductility and malleability.
  7. To harden only the surface and keep a tough core (case hardening).
  8. To improve electrical and magnetic properties, and corrosion/heat resistance.
  9. To remove gases and improve the structure of castings.

✓ Answer checked by Claude Opus 5.5 (high effort)

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