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How to Use Heat Treatment to Age Alloys and Harden by Quenching

Steel alloys are heat-treated along a continuum of strength and brittleness. Annealing softens steel alloy. Heating and quenching produces temper or hardening depending on how hot the alloy gets. Other kinds of alloys such as aluminum or stainless steel require different processes to manipulate their molecular grain, which accounts for their characteristics. After heating and quenching, alloy grain ages as molecular structures change. A process known as precipitation heating accelerates the process of aging. The chemical process is very complex, but the precipitation heating process is not much more complex than steel hardening.

Things You'll Need

Heating furnace
Controlled cooling environment

Instructions

- 1
  Superheat the alloy as you would in the hardening process to around 350 degrees Fahrenheit, depending on the desired temper. You must use a heating source you can heat continually, without fluctuations in heat for 24 hours.
- 2
  Heat soak the alloy. This is the primary difference between typical tempering, hardening and precipitation heat-treating. Heat-soaking the alloy means to leave it at the superheated temperature for 9 to 24 hours depending on the specified temper and alloy you're working with.
- 3
  Cool the alloy to room temperature very gradually. To ensure gradual cooling, you may have to insulate the alloy from exposure to cold air. You can sometimes use an insulating material such as sand. The alloy can be immersed in superheated sand, so the insulating sand cools around the alloy, helping to moderate the drop in temperature.

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