Your Introduction to Heat Treatment
September 20, 2017


Simply put, heat treatment improves and strengthens a part’s material properties – in our case, it’s aluminum. This process involves controlled heating (to extreme temperatures) and cooling to achieve a desired result such as hardening or softening aluminum.
When heat treating, we use techniques including solution treatment, quenching, and precipitation strengthening.
While heat treatment provides better surface finishes, improves machinability and strengthens mechanical properties, it’s not always necessary and fully depends on the part’s function. So, for example, we’ll opt to skip heat treatment if the customer’s part doesn’t require high strength or if the part serves a strictly aesthetic purpose.



To achieve T6 temper, the process consists of three steps:

  • Solution Treatment: Heat the casting to ~1000 F for several hours
  • Quenching: Drastically cool part in a water bath
  • Artificial aging: Reheat the part a final time at ~300-400 F

Due to extreme temperature differentials (in a matter of seconds), T6 can sometimes warp parts. However, we’ve developed certain procedures and methods to control and minimize warping through precise part orientation and temperature and timing adjustments.
T6 is often associated as being the default heat treatment for aluminum, and many engineers aren’t aware of T51.


We allow castings to naturally cool  from the mold. Once cooled, they are artificially aged at 400 – 450 F. With T51, part distortion during heat treatment is not an issue.


Heat treatment and permanent mold casting make for a great combination in your part’s success.
We know heat treatment improves mechanical properties and increases hardness, yield strength, and tensile strength. We also know, as stated in several of our previous articles, that permanent mold achieves great benefits, including reduced casting costs and improved quality.
Typically, people use heavier metals and materials to achieve high strength and specific mechanical properties. Our combination of heat treatment and permanent mold casting provides high strength to weight ratio and achieves similar mechanical properties while utilizing lightweight materials.
Get in touch with us if you’d like to learn more about our heat treatment options and get additional information about combining heat treatment with permanent mold casting.

Minimum Mechanical properties for Aluminum 356 (AA 18-08)

TEMPER UTS (ksi) YS (ksi) Elongation Typical Brinell Hardness (BHN)
T51 25 55-85
T6 33 22 3 65-95
Categories: Knowledge