Silencer material comparison, weight vs strength

[Rich V]

One of the first decisions in building a silencer is the choice of materials to use in the build. Strength, weight, corrosion resistance, durability and machinability are some of the parameters we need to chose from. For the F1 builder there is a limited choice in materials when you exclude the exotics.

I have a good understanding of the basic characteristics for the common metals used but I never did a detailed comparison of their strength vs weight properties. I decided to do a direct comparison of the most common materials used in F1 cans and came up with this table.

The yield strengths were obtained from major metal supplier data sheets. The numbers will vary a bit by manufacturer and specific grade but the numbers used here are typical for the material. The bursting pressures (yield pressure to be exact since I used yield not ultimate strength) were calculated from this site: http://www.engineersedge.com/calculator ... t_calc.htm
Specific strength is the yield strength divided by the density. This gives a direct comparison of the strength based on weight.



A few observations and comments.
The grade 5 Titanium (strongest of the commonly available Ti alloys) has the best weight to strength of the materials in this comparison. It is generally not available as seamless tubing.

A common question on this forum is which aluminum alloy to use. 7075 has nearly double the bursting strength of 6061. Unfortunately 7075 is generally not available as tubing to the small volume buyer. Aluminum also has a low service temperature and is prone to stress fatigue.

The 300 series stainless steels are the most common material chosen for the silencer tube. Seeing how poorly it stacks up in strength is an eye opener.

17-4 stainless is probably the strongest stainless steel commonly available. In the H900 condition it has nearly 5 times the yield strength of 316ss and has a Rc hardness in the low 40s. Even in the annealed form 17-4 has 3.5 times the strength of 316ss. 17-4 ss will maintain this strength ratio vs 316 up to 1000 F. It is available as seamless tubing unfortunately I have yet to find a supplier that sells in small quantities.

Hope this is useful

[Capt. Link.]

While 17-4 is great material 300 series works very well for suppressors and few people need more.

[Fulmen]

You should do the same comparison for elevated temperatures, it doesn't take that much heat for SS to beat aluminum.

[Capt. Link.]

You should do the same comparison for elevated temperatures, it doesn't take that much heat for SS to beat aluminum.

I'm sure you meant it the other way around Good morning!

[Rich V]

You should do the same comparison for elevated temperatures, it doesn't take that much heat for SS to beat aluminum.

Aluminum is good to about 400-450F after that the yield strength falls like a rock.

[silencer_kid]

Aluminum is good to about 400-450F after that the yield strength falls like a rock.

perhaps that cliff starts around 250F

i guess really the 1st question is, what exactly is the application. the variables yield quite a bit of combinations and thus choice of materials really has to start with the application. full auto 223 for 10min, bolt 22, sniper in the jungle, sniper on rooftop with bi-pod, etc.

heat treated 4130 is a good item in certain places. iconel even better. heat treating in an argon or vacuum chamber

in this group of metals, SS and Ti(cp2) are best at elevated temps. and you can see where SS is better than Ti(cp2). above 500F i would choose 321 SS. not sure what the 6al4V Ti would look like on this chart, perhaps like cp2 but a tad more to the right. i also like matweb for getting props of materials.

[Rich V]

Correct 7075 losses strength faster than I remembered. 400-450 °F is the annealing temp.


Temperature 500 °F 8990 psi


Temperature 399 °F 12600 psi


Temperature 300 °F 27000 psi


Temperature 212 °F 65000 psi

[Morgan]

4130 is readily available in seamless tube and bar. It's inexpensive, medium strength, and easily parkerized. Machines great and welds easily. I've had great luck with it.

I have a 22 silencer I made that's 1 year old and the shell is bare 4130.... Cleaned it 2-3 times over the year and 0 corrosion so far after many bricks of 22. I just put a squirt of clp down it after shooting.

[silencer_kid]

if you temper 4130 you can get great strength (i am looking for the yield vs temp charts). 4130 should definitely be on the list, maybe for outer tube and then a SS 321 of iconel blast chamber.



Iconel is the champ

[Grounded]

if you temper 4130 you can get great strength (i am looking for the yield vs temp charts). 4130 should definitely be on the list, maybe for outer tube and then a SS 321 of iconel blast chamber.



Iconel is the champ

Inconel wins until you have to buy and then machine it haha.

[silencer_kid]

Inconel wins until you have to buy and then machine it haha.

the world is full of pros & cons.

[jnjproto]

I always see 17-4 listed as a some what common high performance alloy, but I have not seen 15-5 mentioned is there a reason? Thanks.

[Rich V]

I always see 17-4 listed as a some what common high performance alloy, but I have not seen 15-5 mentioned is there a reason? Thanks.

There are several precipitation hardening stainless steels available. 15-5 is a variant of 17-4

http://www.aeonmaterials.com/Pages/PHGrades.aspx
15-5PH Precipitation Hardening Stainless Steel Alloy (S15500) is a variant of the older 17-4 PH (S17400) chromium-nickel-copper precipitation hardening stainless steel. Both alloys exhibit high strength and moderate corrosion resistance. High strength is maintained to approximately 600°F (316°C). The 15-5 PH alloy was designed to have greater toughness than 17-4 PH, especially in the through-thickness (short transverse) direction. This improved toughness is achieved by reduced delta ferrite content and control of inclusion size and shape. The composition and processing of 15-5 PH alloy is carefully controlled to minimize its content of delta ferrite, which is present in the 17-4 PH stainless steel material. Inclusion control is done by consumable electrode remelting using the electro-slag remelting (ESR) process. The 15-5 PH alloy is martensitic in structure in the annealed condition and is further strengthened by a relatively low temperature heat treatment which precipitates a copper containing phase in the alloy. Like the 17-4PH alloy, the 15-5 PH stainless steel alloy requires only a simple heat treatment; a one step process conducted at a temperature in the range 900°F (482°C) to 1150°F (621°C) depending on the combination of strength and toughness desired. A wide range of properties can be produced by this one step heat treatment. Heat treatment in the 900°F (482°C) range produces highest strength, although slightly less than those of semi-austenitic alloys like S17700 (17-7 PH) or S15700 (15-7 PH). The latter precipitation hardening alloys generally require more steps to complete heat treatment. The15-5 PH alloy is generally better-suited for plate applications than are the semi austenitic alloys.

[silencer_kid]

so, heat treated 4130 has outstanding yield at high temps. and look at the UTS curve !! with proper heat treating you could likely downsize 4130 beyond the point of any weight savings that Ti might offer you. 4130 is also much less $$.

[Rich V]

The 41xx series steel has some very good properties, in particular the strength/cost ratio. Unfortunately corrosion is an issue that needs to be addressed. All of my F1 cans condense water inside even when running a 308 cartridge. This is less of a problem when you get the can good & hot but even then upon cooling water can condense. Also the heat treating process is beyond what most F1 builders can manage so you will need to buy the tubing at the higher temper. Looking at the yield strength curve (UTS is of little value here) it's not bad but much less that 17-4 SS, my favorite first choice. It does beat the the 300 SS series by a lot so if you can deal with the corrosion issue it's a good choice.

[silencer_kid]

4130 can be plated to give some corrosion resistance. a form-1 builder can take raw materials (a tube you were using for a flashlight build) to get heat treated or send out to be done, then after you get it back you decided that tube was for the form-1 item (silly batf rules, etc ), or buy & machine the tempered 4130, etc. oh crap, i just ordered some tube stock, i do have intentions to use some of it for form-1 builds, but dont have form-1's yet.... crap, batf is coming for me, i have to go hide now.

if water condensation is an issue, you can use some rubbing alcohol in the can when you are done using it, it will disperse water and will then both evaporate out.

[cal50]

Titanium at elevated temps is susceptible to oxygen/nitrogen contamination.
If you plan on running your can +600 F degrees I would choose another material.

[Historian]

While researching sleeving for aluminum racing engine I ran across this
interesting information germaine to the above conversation:

<< http://www.raceenginedevelopment.com/se ... tallation/ >>:

: ... Most aluminum production automotive engine blocks use dry gray iron cylinder liners
for the piston and rings to ride on. A dry liner is either cast into or press fit into the aluminum
bores of the block.

The aluminum bores transfer heat from the liner to the coolant surrounding the aluminum bores.
Some engines have wet liners, the Ferrari being one example."

Has anyone thought of lining an aluminum can with a thin SS sleeve?

Notional image: << http://assets.suredone.com/1799/media-t ... leeve.jpeg >>

[Capt. Link.]

I have always wanted to try having a aluminum suppressor electroplated with chromium like they do for the aluminum racing engines of motor cycles.The hard finish would protect the aluminum and allow heat transfer too.The process is called Nikasil.http://www.kenoconnorracing.com/Cylinde ... eeves.html.
With only a few thousands of a inch of this tough material would allow aluminum baffles and blast chambers to be protected.This would make aluminum more viable for suppressors and have a high weight to strength ratio with the endurance closer to hard stainless steel if not greater.

[silencer_kid]

Has anyone thought of lining an aluminum can with a thin SS sleeve?

definitely can be done, perhaps not that easy to accomplish unless you have good machinery. expansion rate diffs might be an issue. perhaps just for the sections that need it, etc.

[Historian]

Thought came up while using a flexible art pallet knife
and noticed how thin and flexible it was.

Find thin, flexible SS steel sheet.

To line a 1" diameter aluminum tube you would cut
a strip 3.14" wide and 5.5" long.

Then roll a SS 'joint' [ for young members ] around a 1" dowel.
Easy fit into tube like lining a cylinder wall, without any machining.

Question, where can one find thin SS sheets?

[T-Rex]

Has anyone thought of lining an aluminum can with a thin SS sleeve?

As silentkid pointed out, it is doable. However, the time in machining and designing would, most likely, outweigh the benefit.
You'd, in essence, be substituting Ti.

I would like to see the Capt's idea followed-up on. I know nickel-plating Al is not a simple task so I wouldn't assume chromium to be much easier. Definitely a task for someone who is already setup to perform such a task or high volume orders. Should be easy to clean, at the least.

[Capt. Link.]

Has anyone thought of lining an aluminum can with a thin SS sleeve?

As silentkid pointed out, it is doable. However, the time in machining and designing would, most likely, outweigh the benefit.
You'd, in essence, be substituting Ti.

I would like to see the Capt's idea followed-up on. I know nickel-plating Al is not a simple task so I wouldn't assume chromium to be much easier. Definitely a task for someone who is already setup to perform such a task or high volume orders. Should be easy to clean, at the least.

This Nikasil is a name brand but the coatings are numerous.TiAIN,TiCN,TiN,AITIN,Zirconium Nitride to name a few.Military rifle bores and chambers have been coated for years w/ electroless nickel.If this can be applied to titanium the surface erosion at higher temperatures will be eased. I wonder if this could be applied to the failed titanium barrels of the past.
I've lined chambers as Historian suggested w/ .010 SS sleeves.The foil is used for heat treatment and is widely available in various thicknesses.You can also buy it as Shim Stock "in a can".
You can have any ferrous metal done with electroless nickle now as many platers have the license to do so.A new 4130-4150 DOM inside plated chro-mo suppressor with a slow rust deep blue would be so very nice.

[BinaryAndy]

This Nikasil is a name brand but the coatings are numerous.TiAIN,TiCN,TiN,AITIN,Zirconium Nitride to name a few.Military rifle bores and chambers have been coated for years w/ electroless nickel.If this can be applied to titanium the surface erosion at higher temperatures will be eased. I wonder if this could be applied to the failed titanium barrels of the past.
I've lined chambers as Historian suggested w/ .010 SS sleeves.The foil is used for heat treatment and is widely available in various thicknesses.You can also buy it as Shim Stock "in a can".
You can have any ferrous metal done with electroless nickle now as many platers have the license to do so.A new 4130-4150 DOM inside plated chro-mo suppressor with a slow rust deep blue would be so very nice.

Nikasil is, I believe, silicon carbide in a nickel matrix. That should be about as good a coating as one could use on an aluminum can. It won't add anything appreciable to strength per se, but it might do wonders for wear resistance.

TiALN, TiN, ZrN, etc. coatings are generally applied with PVD or CVD processes. PVD coatings are extremely thin (.00002" to .0002" depending on the coating). A PVD coating supposedly will not adhere very well directly to aluminum, so you would nickel plate the parts first. Also, PVD is a line-of-sight process, so it won't get inside holes or tubes.

CVD coatings are a bit thicker than PVD and they generally adhere better and take abuse better. This is the coating you'll see on carbide cutting inserts made for heavy roughing. It's not line-of-sight, so it will get inside holes. Unfortunately, the process temperature is quite a lot higher than the melting point of aluminum, so that won't work. Irritatingly, it also can't be used on Ti, 300-series SS, Precipitation-hardening SS, or 4000-series alloy steel. It does work on 400-series SS and most tool steels.

I've been doing some pretty extensive research into silencer materials and coatings for a while now, and so far heat treated 4140/4340 with a thermoreactive diffusion coating is looking to be a pretty clear front runner for a lot of things. The material is readily available (even in seamless tube), inexpensive, and easy to machine. With the right heat treat it's about the right hardness, and the yield strength is outstanding. A 4140 tube can actually be made lighter than a Ti tube for the same diameter and bursting pressure.

The coating I'm looking at is made up of Vanadium Carbide and Niobium Carbide with a similar thickness to CVD coatings (.0002"-.0005"). Since it's a diffusion coating, adhesion should never be a problem. It doesn't get much better than this for resisting wear and heat, and the coating layer is thick enough that it should do very well at preventing corrosion. I'll be putting some of this theory to the test in the next few months.

[dave.223]

if you temper 4130 you can get great strength (i am looking for the yield vs temp charts). 4130 should definitely be on the list, maybe for outer tube and then a SS 321 of iconel blast chamber.

So I'm trying to find some info on 321 vs 316 ss and from my research, I did not find 321 to have any properties that are better than 316. I did find 316 to have better strength and corrosion resistance. is there any reason to use 321 instead of 316? Or should I say what alloy- 321 or 316 would be better for use in a tube?
I know 316 would be a better choice for baffles.