Equivalent to RHA

[swertel]

Our supplier can't supply any more RHA. The mill is busy fulfilling other orders is the reason. I need to find an alternative for testing.

Our vendor recommended 4340 heat treated to RHA, but I do believe our thickness is too thick for a full-thru heat treat. Don't know yet, gotta check the details.

No matter what we do, we'll have to get customer approval for the variation, but I'd like the variation to be as close as possible to RHA. Any ideas?

(Note. Ignore the website in my signature. That's my side job.)

--Scott

http://wertel.eng.pro

 

[IRstuff]

MIL-A-12560 and MIL-DTL-46193 give rather different compositions for armor steel. The protection levels are specified at different obliquities, so kind of hard to compare, but they look roughly comparable, although the MIL-DTL-46193 steel appears to be somewhat better.

There's also MIL-A-46099, but it doesn't give a composition, and the performance doesn't really match either of the above.

TTFN

FAQ731-376

 

[swertel]

Thanks for the others. I'll look them up and see if we can find a supplier to make it. Our current spec is for MIL-A-12560 Class 1 or 3.

--Scott

http://wertel.eng.pro

 

[zeusfaber]

Suggest you talk to the customer before hunting for an alternative material.

You'll have a better idea of what to look for if you can understand the threat he is designing for, and which of the properties of RHA he's keenest not to lose.

A.

 

[swertel]

It's not development, it's a production system and we need the RHA (MIL-A-12560) for lot acceptance testing.

Step 1) Find what else is out there.
Step 2a) Determine what alternatives are close to 12560.
Step 2b) Determine if we can obtain said alternatives.
Step 3) Get customer deviation.

--Scott

http://wertel.eng.pro

 

[swertel]

I reviewed MIL-A-46099C and MIL-DTL-46193A. Both seem like comparable matches to MIL-A-12560H for my application with the obvious limitation of maximum plate thickness.

Has anyone had experience obtaining materials per the specs but with taking exception to the thickness? In other words, I'd buy MIL-A-46099 or MIL-DTL-46193 except thickness shall be X.X instead of .5 (or .7) inches. I would then include additional flatness and waviness requirements per MIL-A-12560 for the desired thickness. It seems to me that buying a MIL-A-46099 or MIL-DTL-46193 at a different thickness would be the same as buying a MIL-A-12560 and therefore I would still run into the problem with available suppliers of the material.



--Scott

http://wertel.eng.pro

 

[swertel]

Our armor plate supplier (Esco Corp) had mentioned to us that in prior times of shortages, they have used MIL-S-5000 (4340 Alloy Steel) and through hardened it - by heat treating - to the same hardness as MIL-A-12560.

It seems like a viable solution and I can write up a statement of work to make sure all metrics match MIL-A-12560 except for obvious ones like chemical composition of the material. Therefore performance for penetration testing should be on par.

Has anyone else used 4340 as an alternative?
Any other vendor recommendations?
(Note, any vendor listed may be of value, but the likelihood that your vendor gets its material from the same mill as mine is pretty good, if a US supplier, so in the end it won't make a difference. But, still worth checking into.)

--Scott

http://wertel.eng.pro

 

[IRstuff]

I don't think any of the specs themselves dictate thickness, as the appendices tell you what thickness is required for which threat protection level. So, I would think that your procurement can be for any thickness you need, so long as the supplier can deliver the goods.

TTFN

FAQ731-376

 

[KENAT]

Not quite the same thing but a few years ago in the UK we started getting a lot of our high grade AL from Russia.

Have you looked at foreign sources for your material. May be difficult to the MIL std but just throwing it out there. Not sure if there'd be import/export/contract/security issues either.

KENAT, probably the least qualified checker you'll ever meet...