Monel k500 in 120ksi min yield strength

[aroundhere]

Years ago, We had k500monel that had yield strengths in the 130ksi range. I am discovering that most k500 that is available is 95ksi-110ksi. Im thinking we must have had a mill run of the higher strength material where I used to work. Does anyone know if monel k500 with yield strengths around 125ksi is even available? I did find a couple of suppliers that had a 1 ft drop, but I need to find a future source. Im in search of 1.75 or 2.00" BTW.The length qty is low. The parts are only s couple of inches long, but they are very complex.

I thought that maybe I could buy it in the "annealed" condition, then heat treat it to get the numbers up. The heat treater I use said that he had a spec he could try, but he has never treated monel before. Can anyone tell me if it is very uncommon to find k500 monel round bar with yield strengths of around 125ksi? THe Nace spec states that monel be no harder than 35rC. It would be easier to machine and less likely to gall with the mating parts compared to inconel 718. Am I beating a dead horse? If it is not readily available for future use than we have to use inconel.

 

[EdStainless]

The commonly available stuff is cold drawn, annealed, and aged.
The higher strength is cold drawn and then directly aged.
This material isn't as tough and doesn't have as good of fatigue properties, but it is stronger.

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P.E. Metallurgy, Plymouth Tube

 

[aroundhere]

Ed, If I wanted to get the Yield up, could it be annealed, then aged again? My main problem right now is finding a source for the higher strength condition. Everyone stocks the lower strength. I have another question that I just noticed. MonelK500 has more nickel than inconel 718 ,but it easier to machine. Is this due to the small amount of Cobalt in the Inconel? We are starting to deal with more of the NAce cert tools, so I am beginning to use these materials more than the 17-4's.

 

[EdStainless]

Nope, once annealed you have no choice.
K-500 is very expensive, and not my favorite.
718 Does not have as good of corrosion resistance, but it is very strong after aging.
The two are totally different metallurgy.

There are a bunch of PH stainless grades, some a lot stronger than 17-4.
This could be hunt.

Another option would be cold finished 625.

The question is what do you really need.

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P.E. Metallurgy, Plymouth Tube

 

[aroundhere]

The main priority is corrosion resistance. The elastic modulus must be as high as possible, so titanium is out. Since we are trying to stay withing the Nace mr0175 as much as possible, most of the PH stuff is out. Since the part has ebwelding and will be a part that we want to last a very long time (downhole logging tool that will see some sour gas wells and h2s)and is very expensive, corrosion resistance and life is priority. We also want it to be non magnetic. The list gets short rather quick. We need 120ksi yield strength due to downhole pressures of 20k. Nitronic 50 HS is like a cold worked 300 series right? It isnt a great choice.

Back to heat treating. If the stock monelk500 is cold worked, then annealed, then aged......can it be heat treated to boost the yield strength?

thanks

 

[metengr]

No. The older Monel alloys for those of use who were around remember they were formulated for higher strength properties, especially for feedwater heater tubing.

 

[EdStainless]

K500 will make higher strength only if you get it cold worked with no anneal, and then age it.
So a logging housing that you will leave in place, not many good choices and none will be standard.
Cold worked C22 (or 686) would be the best. NACE MR0175 give some guidance, but it isn't half the story. It says nothing about corrosion resistance, especially for long term exposure.
Strength only plays a factor in external pressure if the walls are not uniform or there is a dent.
We supply some welded and drawn tube for this service, but nothing available in the size that you are looking for.
W&D is very good because the wall is very uniform (we anneal and re-work to get strength).

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P.E. Metallurgy, Plymouth Tube