4340 -- elevated temp properties vs 17-4?
4340 -- elevated temp properties vs 17-4?
(OP)
I am making a part which needs to maintain as much yield strength as possible in the 1000 to 1500 degree F range when subject to pressure. The part failed when made out of 4140. It did not fail when made from Inconel-718 -- but that was expensive. We are beefing up the part which will help.
I need a lower cost material and am thinking of 17-4 PH, 4340, 300m, 286A, Greek Ascoloy, or Nitronic 50/60. Any ideas what as the most yield strength at 1100, 1200, and 1500 degrees? It would be subject to these temps just for a few minutes on a few occasions but otherwise will generally be below 600 degrees F.
I understand that materials which rely on their heat-treatment for strength give that up as they approach the temp they were treated at.
I need a lower cost material and am thinking of 17-4 PH, 4340, 300m, 286A, Greek Ascoloy, or Nitronic 50/60. Any ideas what as the most yield strength at 1100, 1200, and 1500 degrees? It would be subject to these temps just for a few minutes on a few occasions but otherwise will generally be below 600 degrees F.
I understand that materials which rely on their heat-treatment for strength give that up as they approach the temp they were treated at.





RE: 4340 -- elevated temp properties vs 17-4?
RE: 4340 -- elevated temp properties vs 17-4?
You need to narrow your design conditions for your component. What is the pressure you are using for your application? What are the contents under pressure? Is this a pressure vessel?
Here is some general advice; you should use 1500 deg F as the maximum service temperature (regardless of time duration or frequency), along with defining a maximum allowable working pressure. Once you have these parameters established, you can search through various Ni-base alloys or austenitic stainless steels (Type 304,304H, 316,316H) as suitable materials.
IF this is a pressure vessel, I would use the ASME Boiler and Pressure Vessel Code for design and seek technical expertise.
RE: 4340 -- elevated temp properties vs 17-4?
But does anyone know the 0.2% yield strength at 1500 degrees for each material or at least for 4140, 4340, and 17-4? Won't that give some quick insight?
I am not sure that 1500 F numbers are published for each material since it is above the design use for some of them.
RE: 4340 -- elevated temp properties vs 17-4?
The 17-4PH material has unpredictable properties above 600 deg F. Does this answer your question? Also, if you are going to use these materials in a pressure containing application, I can tell you with certainty that none of these materials are permitted at 1500 deg F.
RE: 4340 -- elevated temp properties vs 17-4?
RE: 4340 -- elevated temp properties vs 17-4?
I know none of them are suitable for 1500 degrees. In my original post I said 1000-1500 and asked which was strongest at high temps. I want to know which moderate cost material would likely last the longest at high temps. In no way am I asking for a 1500 degree rating.
RE: 4340 -- elevated temp properties vs 17-4?
Use 304 or 316 stainless steel.
RE: 4340 -- elevated temp properties vs 17-4?
I thought of 304 and 316. I forgot to say one other requirement -- it has a ratchet-tooth on the back of it. That part will not get red hot ever, but it needs to be hard enough to not wear easily. So 304, 316, and Nitronic 50/60 are ok but not great in that regard since they are Rockwell C30 or so.
I am excited about 418. What do you all think?
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It is still about 60KSI yield at 1100 degrees F -- that is twice as strong as 316 at room temp. It is hardenable. It machines ok in annealed form. Seems like the best overall solution. Agree or disagree?
RE: 4340 -- elevated temp properties vs 17-4?
RE: 4340 -- elevated temp properties vs 17-4?
The 1200 degree, 1000 hour stress rupture for 316 is 24KSI.
For 418 it is 11KSI.
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So if I went by this, 316 would be superior. However, 316 is Rockwell C-zero basically. That is not very good for our exposed ratchet teeth. I think I need the hardness of the 418, and just have to live with the high-temp limit of around 1100 degrees.
RE: 4340 -- elevated temp properties vs 17-4?
RE: 4340 -- elevated temp properties vs 17-4?
As arunmrao mentioned, surface hardening of Type 316 can be done using the nitriding process. This will improve the wear resistance, and if it is one of the newer processes, will not degrade the corrosion resistance. Use the following link for more information:
http://www.kolsterising.bodycote.com/
RE: 4340 -- elevated temp properties vs 17-4?
I don't know of any Fe based alloys that have significant strength at 1500F.
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