Material Selection - Muzzle Blast

[mewhg]

I am designing a type of muzzle break for small arms. One part of the brake will be directly impinged upon by the hot, erosive muzzle blast after the projectile has left the barrel.

I am looking for material suggestions. I am considering Inconel but was wondering if there might be some other, easier to machine material options.

TIA

 

[alexit]

Most of the military rifles I have use plain carbon steel, 4140 or so. The parkerized finish holds up well to the corrosion...and you have to clean the barrel anyway so the brake gets cleaned often.

Some of these rifles (from the 50's) were very well used in their country of origin (barrels shot out). The brakes had no discernable wear even after 40,000+ rounds.

 

[TheBlacksmith]

Exactly what I was thinking, by the time you get to the muzzle brake pressure and temperature are dropping and then you release a lot of the pressure to control muzzle climb, so whatever works for the barrel should suffice for a brake.

Blacksmith

 

[mewhg]

In this case there is an existing design that experiences a lot of erosion. Stainless steel, 4140 and chromed 4140 have all been tried.

TO clarify this is not a traditional pass thru brake but one that is directly impinged upon by the gases and that is very close to the muzzle.

 

[EdStainless]

Most stainless grades should be fine. Since you are not puting this on a large cal. - cont. fire application it shouldn't get too hot.
Will this be tube-over-tube or machined from bar with drilled ports? How important are mechaical properties? Off hand I would suggest that you consider a duplex stainless. It will be strong and corrosion resistant.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[mewhg]

Ed, think of a cone with a hole drilled in the small end for the projictile to pass through. The large end of the cone is away from the muzzle (so the gases flow around the outer part of the cone). Its the hole in the cone that gets beat up. It will be initally a machined/turned part but may be converted to an investment casting.

There really is very little stress on the cone so mechanical properties are not that important.

I thought of a ceramic but it might be expensive to form something this size.

What type of duplex stainless were you thinking about?

 

[TVP]

Grade 2205 is the most common duplex stainless steel that is offered by foundries for investment casting.

 

[btrueblood]

Is there a sharp corner at the edge of the metal at the tip of the cone, that is exposed to the highest-velocity gases, and is that sharp edge what is eroding? Can you round that corner, or is its sharp edge contributing to the brake performance? If the sharp corner must be there, you may want to look at an insert part (powder metallurgy or similar) in a tribological alloy (e.g. tungsten carbide) that is then brazed onto the sheet metal cone.

 

[EdStainless]

If you can insert the edge look at making the unit from low alloy steel and use a cobalt alloy for the insert. An alloy like Ultimet from Haynes will offer the whole package,resistance to wear, erosion, corrosion, and high strength.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[mewhg]

Ed,
The Haynes website is what I was looking for....thanks.

It looks like I can make the entry nozzle of the cone from one of their alloys and the rest from a cheaper stainless steel. Just need to be able to weld the two together.

 

[jackboot]

mewhg,

What does the Barrett .50 use? I would assume that arrangement would work anywhere since (as far as I can tell from the website) they have a large amount of impingement on their brake.

As far as the insert - we use carbide in extremely abrasive/erosive gas flows. It can be cast to a reasonably accurate dims (+/-0.010).

jackboot

 

[mewhg]

Jackboot,

The Barrett brake is an investment casting, material unknown. This brake is a little different as the 'cone' has a hole not much bigger than projectile diameter and it is very close to the muzzle....closer than the Barrett sits.....

 

[rorschach]

Also consider making the whole thing out of carbon or stainless steel and flame spraying a ceramic coating onto the part to sut fdown on erosion.