Normalizing

  • Normalizing process is a heat treatment process for making material softer but does not produce the uniform material properties as produced with annealing process.
  • The most common reason for normalizing process is to adjust mechanical properties to suit the service conditions.
  • The other purpose of the normalizing are:
    1. To relieve the internal stresses,
    2. To refine the grain structure, and
    3. To improve the machinability.
  • Normalizing involves heating steel to above 50°C above the upper critical temperature, (for hypo-eutectoid steel) and to 50°C above the lower critical temperature (for hyper eutectoid steel).
  • Holding at this temperature for shorter time to prevent grain growth and finally, cooling in air.
  • The time allowed should be sufficient so that the temperature is equalized throughout the section.
  • The structure produced by normalizing is similar to that of annealing. But air cooling is faster than furnace cooling. Thus the normalized steels possess fine grains than annealed steels.
  • The normalized structure of low-alloy steel consist of sorbite (fine pearlite) and fine ferrite.
  • The increased rate of cooling in normalizing results high hardness and low ductility than annealed steel –> machinability will be easy.
  • Normalizing is usually performed after forging or casting, to put steel in the best condition for machining or hardening.
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All Comments

  • Please concentrate on atomic level explanations

    D muni bhargav Apr 14, 2016 8:17 am Reply

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