Full Annealing

Due to the nature of the investment casting process, a full annealing treatment is sometimes needed in order to minimize the risk of cracking in the parts during any subsequent hardening or to improve machineability.


ThermTech runs full annealing treatments in batch-type furnaces for optimum process and lot control. All these furnaces are certified to AMS 2750, as they are in full compliance with its temperature uniformity and accuracy requirements. Our largest furnace capable of performing the full anneal process has a working dimension of 86” x 51” x 182”.


The process of full annealing steel castings is performed by taking the castings above the critical eutectoid temperature in the 1475F to 1650F range for a length of time commensurate with the cross section size and then slow-cooling them to promote a ferritic microstructure.  This process creates a product with maximum ductility and toughness, reduced strength and hardness, as well as improved machinability and uniform properties. This process can be performed under protective atmosphere or under vacuum depending on the material in question.


We often recommend the full annealing process to customers with investment castings which are too hard due to rapid cooling during the casting process. A common situation that crops up with castings fabricated from any of several commonly used alloys.

The materials for which ThermTech has most commonly run full annealing treatments include:

  • Annealing 4140 steel investment castings
  • Annealing 4340 steel investment castings
  • Annealing 440 stainless steel investment castings
  • Annealing 410 stainless steel investment castings

Depending on individual product needs, ThermTech offers several alternative annealing processes. For investment castings bound for intense machining, ask us about our spherodize anneal treatment. We also recommend asking about any other product needs you might have; ThermTech prides itself on its ability to meet any property and/or hardness requirements!

For a quote, a schedule, or more information about how our full annealing process can benefit your investment casting products, please contact a sales representative today!