Vacuum Solution Annealing and Homogenization
One of our unique abilities is to perform solution annealing and homogenization of stainless steel castings in our vacuum furnaces. Due to the high pressure quenching capabilities of these furnaces, we are able to closely mimic the liquid quench rates needed to perform an adequate solution anneal where the parts corrosion resistance is greatly improved for its service in the food or chemical industries. Most importantly, we are able to run impellers and pump units where minimal oxidation occurs on internal surfaces making clean-up faster and cheaper for our customers.
What You Should Know about Vacuum Solution Annealing and Homogenization
- If you are making a tool or die out of a precipitation hardening steel such as 15-5, 17-4, or 17-7 stainless steel or a super-alloy steel, such as Inconel or Hastelloy, then you might need vacuum solution annealing to ensure the parts are in the correct condition for subsequent age hardening, or that parts are in the proper phase for optimum corrosion resistance.
- We also have experience in processing exotic titanium and molybdenum dies in our vacuum furnaces. Our largest furnace is 36" wide x 32" high x 72" long with a weight capacity of 10,000 pounds.
- Subcritical annealing uses temperatures below the point which austenite forms. It's a good choice when wanting a relatively low hardness and little to no internal stresses. Cycle times are relatively short as compared to full annealing, therefore it is the least costly process.
- Full annealing involves heating above the point at which you form austenite and then slow cooling at some rate to which the austenite phase transforms into ferrite and pearlite. This tends to be an extremely long process and thus, can be very costly. It does provide low hardness and no internal stresses.
- Spherodize anneal is similar to full annealing but has a secondary step where the part is held at a temperature at which the carbide phase is allowed to assume the shape of a sphere, thus the microstructure consists of ferrite and spheroidal iron carbide. This provides an extremely low final hardness. This is often used for alloys like AISI 52100 that can be difficult to machine.
Treatment Recommendations from ThermTech
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Full annealing and spherodize annealing treatments are extremely long; so, keep this in mind when looking at time schedules. It's very important that the correct annealing process is chosen given the costs, thus a discussion prior to submission of an order is well worth the time.