Best type of SS for comp or flash hider?

[Exodus]

Admin: Please move this thread to the AR Technical Discussion forum. Thx

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Ref: http://www.advanced-armament.com/pdf/manuals/aac_manual_m4-1000.pdf

Scroll down where it says Flash Hider Material

What is High Temp SS?

Ref: http://www.advanced-armament.com/product.aspx?pid=29#pid=119

Their description says it is a "high strength corrosion-resistant aerospace alloy"

http://www.advanced-armament.com/images/accessories_featured_blackout.jpg


I'm wanting to build my own comp/flash hider combo and figure AAC uses the best type of stainless steel for this application.

Regardless of what AAC uses, what SS would be a reasonanabley priced material to build flash hiders out of?

Would 17-4PH and CeraKote be a good combo?

Thanks X

[JonnyVain]

I don't think the blackout is stainless steel.

You don't have too much to worry about with corrosion unless you are running a suppressor.

[Exodus]

I don't think the blackout is stainless steel.

You don't have too much to worry about with corrosion unless you are running a suppressor.

Their literature says High Temp SS (stainless steel)

Yes I'll be running a suppressor.

Thanks

[Frank Castle]

Just about any aerospace grade corrosion resistant steel would qualify as "High Temp SS". 17-4PH is as good a choice as any. If I recall correctly, AAC uses 17-4 for their brakes.

[trg42]

First off, I cringe every time I see marketing info that shows "Aerospace Quality Aluminum / Stainless" etc. Example you see all the time is “aerospace quality aluminum” Guess what….6061-T6 is one of the most common alloys of extrusions. Nothing aerospace about it.

Anyhooo….I digress

First of Precipitation Hardened Stainless claim to fame is NOT corrosion resistance at elevated temperatures (a run of the mill austenitic type 304 is as good), but rather extremely high Tensile and Yield strength. Example Type 17-4PH is over 190Ksi (for comparison, standard structural such as A36 is less than 60Ksi). This grade is often used for applications such as marine cranes, shafts etc

Useless trivia of the day: Precipitation hardening Cliffs Notes version – When you have a cup of tea, you can put more in solution when hot. This is why when you put lots of sugar in tea, you can see it precipitate out to the bottom when tea is cold. The trick is to keep the sugar in solution. With stainless / Aluminum etc, they do this by quenching / heat treatment / artificial aging

At the end of the day, I find it hard to believe that you require that type of Tensile Strength in a brake / suppressor mount. I will go as far to say, 17-4PH is a poor choice, since the general rule with 17-4 is 300degC (572degF). At this temp, strength and corrosion resistance takes a nosedive and can permanently softened. There are far to many better alternatives to 17-4 for your application

Duplex stainless experiences embrittlement at higher temps at over 300degC making it a poor choice

To answer your questions on the best, commonly available and economical alloy a type 316 is the best choice for high temp / strength. Maintains strength and corrosion resistance up to 800degF before properties start to drop. Type 316 differs from other austenitic stainless through the addition of moly . In a pinch Type 304 ( most common ) is a good choice as well

The BEST choice for elevated temperature strength and corrosion are high nickel alloys such as Inconel 625, Hastalloys etc. To put it into perspective, Inconel 625 will maintain adequate strength up to 1800degF . I have seen 625 glowing red hot and maintain strength in a furnace conveyor system. Although Inconel 625 is very common, there are even better high nickle products but they would be total overkill for supressor / brake components