Best erosion resistant material compatable with 15-5PH and scCO2 1

[wasteheat1]

I have an application with a working fluid of super critical CO2 at high velocity causing an erosion issue with a 15-5 PH component. I am looking for the best erosion solution that will match with other 15-5 PH components in the system from a thermal expansion position. Working temperatures to about 900 degrees F.

 

[EdStainless]

Which heat treat condition is your 15-5?
How much harder do you need it?

One step would be using 17-7PH in the RH950 condition.

If this is actually erosion/cavitation you would be better off with a Co based alloy.
As strange as it sounds an alloy like Ultimet (

http://www.haynesintl.com/pdf/h2082.pdf

).
Even though it is much softer, will have superior erosion resistance. I have used it for flow control chokes and it out preformed materials that were >50% harder.

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Plymouth Tube

 

[wasteheat1]

The 15-5 is H1025. The CO2 is moving pretty fast, so the harder the better. These are nozzles and it is definately cavitation/erosion. I am looking at the 6B alloy now. I need to check thermal expansion since our temps are semi-high. I will look at the Ultimet again. I did look at it, but since it was considerably softer. I didn't consider it. I will also look at the 17-7PH RH950, but the 15-5 PH H1025 showed signs of erosion after only days of use, and I need it to last for years. I am trying to avoid using a coating, as I don't want to introduce noise into the system if the coating breaks free.

 

[EdStainless]

I have seen the Ultimet out perform Stellite and carbide in cavitation applications.
Look into it.

Sounds like you need a different style of valve.
There are special pressure reducing flow control valves that are used in steam/water flow where cavitation and erosion are serious. One style uses stacked discs to allow more gentle pressure reduction.

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Plymouth Tube

 

[wasteheat1]

I will give the Ultimet a try. This part is in a turbo pump, so the pressure is intended and necessary unfortunately. I just need to find a material that will stand up to the requirements.

Thanks for your help.