Dictionary – Annealing

Annealing can be performed for a variety of reasons, such as reducing hardness, improving machinability, facilitating cold working, homogenising the material, obtaining a desired macro-and micro-structure, or specific mechanical properties, removing internal stresses, etc. Annealing thus covers a wide variety of treatments dependant on the material and the requirements, and can therefore vary from a low temperature sub-critical anneal, to a complex full anneal cycle.

Full annealing produces a softer, ductile steel with lowered tensile and yield strengths. This makes the material easier to machine. After machining further heat treatment is undertaken to produce the desired final properties.

Note. The terms normalizing, stress relief annealing, sub-critical annealing, full annealing, cycle annealing, isothermal annealing, inter stage annealing and process annealing describe different processes but are often confused. Therefore careful consideration should be given of the purpose of the treatment in order to decide which procedure to use.

Annealing related terms

  • Normalizing,
  • Stress relief annealing,
  • Sub-critical annealing,
  • Full annealing,
  • Cycle annealing,
  • Isothermal annealing,
  • Inter stage annealing
  • Process annealing

Each describes a different process but they are often used incorrectly or applied inaccurately.

Therefore careful consideration should be given to the purpose of the treatment in order to decide which is the correct procedure to use.

Holt’s offer annealing treatments for Castings, Forgings, or Wrought Components

Material range through Irons, Plain Carbon to Stainless, Duplex and High Alloy Steels, and up to 2.7m long x 1.5m diameter.

Similar sizes are available for the heat treatment of non-ferrous alloys.

With a wide variety of sizes and types of furnaces, (horizontal and vertical), Holt’s have the capability to suspend long, slender items vertically to minimize distortion arising from the treatment. Available atmospheres encompasses; air, products of combustion, controlled atmosphere and vacuum, with the atmospheres available dependant on the component material, size, shape and final requirements.