If you’ve kept up with company news over the last several months, you’ve probably seen the announcement that we’ve added a hot isostatic press (HIP) in our expanded Cleveland Division.
It’s officially ready for service.
But before the Quintus model QIH 122 was ready to run parts for customers, we completed a detailed survey of dozens of process variables to help us fully understand what our HIP equipment is capable of.
This investigation was critical. First, our customers can rest assured their parts will be processed by a team with an intimate understanding of this cutting-edge equipment. Second, we can communicate to our customers in more practical terms the advantages and disadvantages of HIP. Finally, the data we’ve collected is helping us identify new opportunities for customers in sectors where HIP is making an important impact, including:
- Additive manufacturing/3D printing
- Medical and dental
- Aerospace and defense
- Power generation and oil & gas
Below is a rundown of some of the tests we did, why we did them and what we learned. But if you’re not familiar with what hot isostatic pressing is, read this first.
Full-temp, full-pressure test
We did this test to verify the HIP unit could meet specs promised by the manufacturer. It was a simple test: Crank the heat and pressure all the way up and run a quench cycle.
For this test, we stuck plain steel bars inside the vessel.
Here’s what we learned: With the furnace fixtures we had on hand, we reached a maximum temperature of 2,282 F (1250 C). We’ll eventually be able to process at 2,480 F (1360 C) once updated fixtures are integrated.
The maximum pressure achieved was 30 ksi. That’s 30,000 pounds per square inch, or about 2,000 times the normal atmospheric pressure at sea level.
The goal during the quench portion of the test was to verify the vessel could cool at a rate of 360 F (200 C) per minute. This benchmark was met. (As described below, we observed a much higher quench rate under specific circumstances in a different test.)
Temperature uniformity test
This test measured how well different locations in the HIP vessel kept to the target cycle temperature. Uniformity is important across many applications, but it’s especially critical to meet requirements under SAE’s AMS2750 aerospace thermal processing equipment standard.
It’s always been hard to maintain tight uniformity in HIP equipment. If the window isn’t narrow enough, complex components that must be processed within very specific parameters are at risk of failure.
The test was composed of several cycles. Each cycle ran at a set pressure while the temperature was gradually increased. Temperature readings were taken from sensors placed in different parts of the chamber in 600 F (333 C) intervals.
We tested from the lowest pressure we believed any customer would specify—7 ksi—all the way up to the 30 ksi maximum. We started at 700 F (370 C) and climbed up to 2,282 F (1250 C) in each test.
In every condition we measured, we observed variations no greater than ±10 F. That’s an exceptional reading. We’re aware of competing HIP vessels that see temperature variations approaching ±50 F.
Maximum quench rate
In an earlier test, we verified the furnace could quench at 360 F (200 C) per minute. But specifications can stray quite a bit from that benchmark.
How far afield could we get? The most impressive rate we observed was a staggering 900 F (500 C) per minute.
We should note that the only way to achieve that rate is if there are very few parts in the vessel. A full vessel has too much thermal mass to cool that quickly.
But, the important takeaway was that if a customer came to us with a unique spec calling for a quench rate almost three times the manufacturer benchmark, we’ve got data proving we can do it.
The testing described above ensured our HIP unit and its operators were ready to process customer orders, but there’s more we want to know. We’re running the tests listed below on an ongoing basis.
Testing thermocouples on parts – Thermocouples stationed throughout the HIP vessel tell us what the temperature is inside. But we want to know what the temperature is on the parts themselves. We know that because of the high-pressure environment, thermal conductivity in a HIP vessel is very good (that means the temperature in the pressurized argon environment is likely to be very similar to that of the parts). We want to know for sure how good that conductivity is. Why? Because one of the benefits of HIP equipment is its ability to also solution treat parts. These ongoing tests have helped us determine just how wide an array of parts can be solution treated in addition to being HIP’ed.
Gas cleanliness – Some applications require thermal processing in ultra-clean environments. At best, if contaminants are present during treatments, parts (like titanium or nickel-based superalloys) may discolor. At worst, they’ll fail in service. But the argon used to pressurize HIP vessels is expensive. To reduce costs, we intend to recycle as much of it as we can. With the help of the gas chromatograph we’ve installed, we can more precisely gauge when it’s time to swap out old gas for new.
What it means for customers
As more and more manufacturers become aware of HIP and its benefits, they increasingly consult with thermal processors to learn whether the process makes sense for the parts they produce.
The intensive testing we’ve conducted means we can take those conversations to the next level. Not only can we help customers specify alternative treatments for their parts, we can use what we know about how HIP works to recommend upstream adjustments to materials and manufacturing methods that may result in improved performance and potentially lower overall costs.
If you’re intrigued by the possibilities HIP offers and want to begin developing a treatment program for your parts, let’s connect.