Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.
BinaryAndy wrote:I don't think you talked to the right person about the cobalt. Electroless nickel is around 65 HRC, and cobalt is supposed to be harder. In any case, electroless nickel and salt bath nitriding both outperform chrome in nearly every way.
I would not recommend reworking the heat treatment.
Perhaps, but I talked to the person that answers technical questions like hardness and that’s the answer he gave. Also the reason i said chrome in the first place is because it has a proven track record of working in barrels, i don’t know if electroless cobalt or nickel would be the same or better as barrel lining. Also for both, the amount of coated surface area is very low and thickness is only .001, might be less even.
If properly done is there a reason why reworking heat treatment would be a bad idea? Would it alter dimensions or make it weaker even?
Hannibalbarca wrote:
I’m unable to machine my own cones and am will be using zmachineworx 17-4 cones in h1150 condition though I want to anneal them and get them to h900 though I can’t do that since I don’t have an oven.
H1150 is the annealed condition; annealing is to soften the metal. You want to harden them to H900. You can get pretty close using a torch with things that have a really thin cross section like suppressor baffles. You're looking for the deep gold/bronze color
Hannibalbarca wrote:
I’m unable to machine my own cones and am will be using zmachineworx 17-4 cones in h1150 condition though I want to anneal them and get them to h900 though I can’t do that since I don’t have an oven.
H1150 is the annealed condition; annealing is to soften the metal. You want to harden them to H900. You can get pretty close using a torch with things that have a really thin cross section like suppressor baffles. You're looking for the deep gold/bronze color
A and H1150 are two separate conditions. While their hardness and strength are near identical, H1150 is more dense and has far greater elongation. To get to "A" the material needs to be brought to 1900F.
T-Rex wrote:A and H1150 are two separate conditions. While their hardness and strength are near identical, H1150 is more dense and has far greater elongation. To get to "A" the material needs to be brought to 1900F.
Does that need to be in a solution or would an oven work? Would it be fine in regards to dimensions to bring it to annealed and then to h900?
H1150 is certainly not the same as annealed, T-Rex is correct. And no, you absolutely cannot heat treat 17-4 with a torch. As a precipitation hardening alloy, you have to hold it ("age" it) at the heat treating temperature (900° for H900) for one to four hours.
Annealing and heat treating again will cause dimensional changes, and I'm not sure how predictable that will be. If you don't have access to a vacuum furnace, the surface will probably scale. It can be done, I just don't see how it's worth it for a little extra hardness and strength, especially if you're going to plate it then.
Solution treating is not done in a solution, the structure of the metal actually becomes a solution, hence the name.
Hard chrome is also usually around .001 or less. It can be made thicker, but so can electroless nickel. Either plating can be made .025 thick if you really want to. The difference there is that chrome gets uneven when it gets thicker, whereas electroless plating is almost perfectly uniform. Chrome decreases the fatigue resistance of the substrate, while electroless nickel increases it. EN adheres a lot better, chrome can be prone to chipping of not applied perfectly. Chrome is harder, but only slightly.
Hardening steel is not something the average DIYer is outfitted to do. There are steps critical to achieving a quality final product. While any Youtuber seems adequate enough to do so, no one truly knows the final hardness or if actual tempering has been achieved w/o quality testing.
Turning H1150 into H900 is not an easy process. The metal must be heated to over 1000C, pickled in 2 separate caustic acid baths, rehardened to desired condition, and followed up w/ a final pickle or electro-polish to achieve maximum corrosion resistance.
Using 17-4SS in A or H1150 is not a terrible thing; they're still a very strong and resilient conditions.
The traditional home heat treat for 17-4 is to throw it in a household self cleaning oven through a self cleaning cycle...which is about 900 F. While not precise, it is 'good enough' for a form 1 can. In most HT overheating is far worse than underheating, so your home oven is 'safe' to try on 17-4.
10xx, W and O series steels are easily home heat treated with an oxy-acy torch, though even O series benefits from a bit of a soak at temperature. Torch heating to quickly quench causes fairly light scaling. SS foil wraps prevent scaling just fine for long soaks and are readily available, but holding at reasonably precise temperatures and times pretty much require ovens made for the duty. 900F isn't going to scale an alloy steel, much, but much over than will, so the really hard alloy steels are mostly beyond novice users capability. You can't even send them out to most HT places as they are already 'suppressor parts'. Grrr.... As much as I'd like a nice 440C or ATS34 blast baffle that would last freaking forever, it isn't going to happen unless I buy myself a HT oven! There are lots of great alloys out there (think gas turbine blade materials for wear resistance and hardness!) that are far beyond the usual for suppressors, but they are just too much trouble to work with.
YHM Phantom 30 cal, 22lr form 1 build, 45 cal form 1 in progress
Atlas 10x36
A lead pot with a PID controller can be used for 17-4 H900 treating as well. A bit power hungry and probably only a few at a time but its precise and can soak as long as you like.
BinaryAndy wrote:H1150 is certainly not the same as annealed, T-Rex is correct. And no, you absolutely cannot heat treat 17-4 with a torch. As a precipitation hardening alloy, you have to hold it ("age" it) at the heat treating temperature (900° for H900) for one to four hours.
Annealing and heat treating again will cause dimensional changes, and I'm not sure how predictable that will be. If you don't have access to a vacuum furnace, the surface will probably scale. It can be done, I just don't see how it's worth it for a little extra hardness and strength, especially if you're going to plate it then.
Solution treating is not done in a solution, the structure of the metal actually becomes a solution, hence the name.
Hard chrome is also usually around .001 or less. It can be made thicker, but so can electroless nickel. Either plating can be made .025 thick if you really want to. The difference there is that chrome gets uneven when it gets thicker, whereas electroless plating is almost perfectly uniform. Chrome decreases the fatigue resistance of the substrate, while electroless nickel increases it. EN adheres a lot better, chrome can be prone to chipping of not applied perfectly. Chrome is harder, but only slightly.
Well if I could heat treat this to 45 Rockwell I probably wouldn’t bother with plating.
If electroless nickel is better than chrome, is there a reason why it’s not used in gun barrels? Also for nickel and thickness, caswell kits don’t provide much in terms of total surface that I can cover.
Also for hard chrome lowering fatigue strength, are you talking about hyrdrogen embrittlement?
Well, for one, chrome lined barrels predate the development of commercially viable electroless nickel. I'm sure there are other reasons as well, and some of them just might have some relevance to silencers.
I was not referring to hydrogen embrittlement. Hard chrome, because of how the coating forms, will decrease the fatigue strength of the part even in the best-case scenario. That effect isn't really significant in a barrel, but I imagine it could be in a suppressor.
For not much more than the cost of one of those plating kits you could send everything out for salt bath nitriding (aka salt bath ferritic nitrocarburizing, Melonite, Tenifer, Tufftride, etc.), which is known to outperform chrome in rifle bores and makes more sense for a silencer than chrome or EN.
BinaryAndy wrote:Well, for one, chrome lined barrels predate the development of commercially viable electroless nickel. I'm sure there are other reasons as well, and some of them just might have some relevance to silencers.
I was not referring to hydrogen embrittlement. Hard chrome, because of how the coating forms, will decrease the fatigue strength of the part even in the best-case scenario. That effect isn't really significant in a barrel, but I imagine it could be in a suppressor.
For not much more than the cost of one of those plating kits you could send everything out for salt bath nitriding (aka salt bath ferritic nitrocarburizing, Melonite, Tenifer, Tufftride, etc.), which is known to outperform chrome in rifle bores and makes more sense for a silencer than chrome or EN.
Does it have the same heat tolerance as chrome? And I know you said chrome is prone to flaking but isn’t nickel as well? I would think I’d nickel was better the military or some military somewhere would be doing it or even just some boutique manufacturer. If a plating stands up to the conditions in a barrel then I’m sure it will stand up to a suppressor.
Do you think the extra fatigue stress would completely counter the benefits of hard chrome?
I have 10 form 1s I’d like to do and that will be 150 pieces, some of which are quite small. I highly doubt I’d be able to get a price under a 1000 dollars let alone close to the plating kits. If the Republicans, trump and nra did their job and passed the share act I’d have the extra money to spend but I really can’t justify the extra expenditure what with the taxes.
Nitriding is surprisingly inexpensive per part. It's relatively expensive to do one silencer because there's always a fairly high minimum order (a $250 minimum is common), but with ten silencers I'd be very surprised if you were over $400, and I wouldn't be surprised if you were still under the minimum.
BinaryAndy wrote:Nitriding is surprisingly inexpensive per part. It's relatively expensive to do one silencer because there's always a fairly high minimum order (a $250 minimum is common), but with ten silencers I'd be very surprised if you were over $400, and I wouldn't be surprised if you were still under the minimum.
