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API spec 7-2 has everything you need. You can find older free copies online.

Yeah a better image would help. Sounds like you just need a gas tight rod seal? A plain o-ring won't work very well. Try out a T-seal. They make them in standard sizes to retrofit standard o-ring grooves. Assuming you designed the rod to a standard size. You should be able to get a perfect seal...

Wondering if anyone has used PEEK for a piston seal on here? Application is for a linear seal. Normal design is a standard slipper seal with o-ring underneath a ring of PTFE to energize. If I replace the PTFE with PEEK it should still work I think. Benefit is increased extrusion resistance and...

I typically get material through a third party distributor like SSA. Mill runs are looking more and more attractive everytime we go to make a batch of parts as the shelves are drying up more and more. To make matters worse, I was just quoted 40 week lead time on 300M rounds from Carpenter. Are...

Guess I'll describe the part and why I'm trying to use plate / rectangular bar instead of round bar. The part is essentially a blade that is much taller than it is wide. The dimensions are roughly 8.25in tall, 2.75in wide and 12in long. It's rough machined to this approx size and then hardened...

Yeah my primary material is 300M since it's a vac melt and have had great results at 220 ksi and up. But when you get to parts over 8 inches in diameter finding material is very difficult. And even if you find it, the price is tough. I know there's vac melt 4340 out there too, but it's almost...

Hey all, Found the answer to my question. Short answer is grain structure is mostly retained from whatever wrought process you started with. Grains don't regrow isotropically. They retain the wrought anisotropy. Reasons being materials science that I don't fully understand. At least I learned...

Let me clarify. If the parts are going through a full quench and temper then aren't the grains completely reformed anyway? So even if you started with an amazing forging where the grains follow the shape of the part perfectly, the benefit of the forging is gone after heat treat as the grains...

Hi all, I'm hoping someone can back me up here. I'm making some extreme stress parts out of 4340 round bar per AMS 6415 (air melt). They are machined in the normalized condition then send for hardening. Tempered at 475F to 50-52 HRC. Tensile tests on some test coupons done with the parts put the...

Will and Ed, Sorry for the late reply. Your advice is well taken. I have a pretty good repore with my heat treaters so I'll be leaning on them heavily. That's why they're the experts right? Marco

Hi all, Utilizing 4330 MOD per AMS 6411. After going through the document I found it odd that a temper temperature was not listed in order to hit the minimum mechanical properties specified. Below I list the heat treatment spelled out in AMS6411H. 3.4.5 Response to Heat Treatment Extracted...

btrueblood, You're right. Meant to say fracture toughness. Good catch.

First up, what is the bending stress calculated to be? How is the part loaded? Sounds like it's clearly a fatigue issue so utilizing an ultra high strength steel tempered to max strength might make the problem worse since you usually sacrifice fatigue life for static strength. Also, you...

Hey all, Just got our tensile test specimens back. Results are great: Average of two test specimens: Yield - 237ksi Ultimate - 280ksi Elongation - 11% Reduction in Area - 36% Hardness - 65 HRC So high five to all of you for helping!

WKTalor, I like the idea of doing the finish machine in between the two tempers. Unfortunately I don't think the machine shop and heat treater can handle the hot potato process. The parts will be moving around the country too much and something would probably go wrong with us ultimately picking...

Tbuelna, Thank you. Yeah we looked at the slightly higher carbon version of 300M but it was a bit of a pain to procure so we settled with the regular version. Any negatives to the higher carbon version? Reduced fracture toughness due to increased carbon? WKTaylor, I agree that attempting to...

Ahh right on Tuckabag. It's so frustrating knowing that Parker, Hitech, EPM and all the other seal manufacturers have loads of practical test data that we don't have access to. Makes sense that they don't publicly share their knowledge as that's sort of what distinguishes one from another though...

If leaks are a no go up to 10ksi you're sort of forced into using a metal-metal seal. Israelkk is right about the gas permeation issue with the o ring elastomers (or piston seals). Is the piston functionality absolutely mandatory? Guessing you're using the internal piston to force the fluids out...

Interesting you found a chart. Was it from a supplier? Only thing that I've come across is from Parker's fluid power book. https://www.parker.com/literature/Engineered%20Polymer%20Systems/5370.pdf See Table 2-4 on page 2-5. All of my seal designs have been done by playing with the squeeze and...

Phamjt, Bust open your machine design text again. It goes over everything you need. Make an excel calculator where you can factor in things like internal/external pressure. Calculate your stresses and make sure you're safe. Then do a simple thermal expansion calc to figure how hot you need to...