Simultaneous Aging and Ion Nitriding
Simultaneous Aging and Ion Nitriding
(OP)
I am looking to age and ion (plasma) nitride one of the three following materials to be used for a shaft in a downhole mud motor application. The possible materials are: maraging C-250, Custom 465, or 13-8 stainless. The requirements are: 200 ksi min. yield, Rc 48 max, and uniform shrinkage from heat treating. The core can be no harder than Rc48 because portions of the shaft get HVOF coated with carbide for rotational mechanical seals. Typical aging for most steels is just a few hours whereas the ion nitriding process requires 40 hrs. The shafts currently in use are 17-4 PH at H900 condition. The application requires two shafts to be screwed together and this connection is galliong severely and several shafts have broken. Thus the shaft material yield must be increased and hopefully hardening the threads will reduce/eliminate the galling. Any recommendations?





RE: Simultaneous Aging and Ion Nitriding
RE: Simultaneous Aging and Ion Nitriding
RE: Simultaneous Aging and Ion Nitriding
One more issue to take into consideration is that the nitiding reduces the corrosion resistance of the substance metal. By the way Maraging c-250 is not a stainless steel and will corrode without a proper surface treatment.
RE: Simultaneous Aging and Ion Nitriding
RE: Simultaneous Aging and Ion Nitriding
At 200ksi yield you will have almost no fatigue life. Every little nick and machining mark has a chance of initiating cracking.
Custom 465 will give you the best mechanicals at this strength level.
If you are looking to use the nitriding to reduce galling then you will only nitride one part, and it only needs to be superficial. If a little doesn't work, more won't help.
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