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Triple Hardened/Hardness Steel


Laviduce
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Hello Everyone,

 

I was wondering, does anyone know of this mystery steel system called "triple hardness steel" ? I was trying to find information on it like layout and hardness (BHN or VHN) but i could not find anything concrete on it anywhere. Although it gets mentioned in the AFV community fairly regularly, I can not find it anywhere. If anyone knows, please share it. Thanks in advance !

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4 hours ago, SH_MM said:

Triple hardness steel and dual hardness steel is created by rolling multiple steel plates with different properties together in multiple stages.

 

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This requires more stages of rolling (IIRC triple hardness steel requires four), hence it takes much more time to make.

 

I'm not sure why you'd bother rolling it - it would severely limit the amount of hardness you could give the high-hardness plate at the centre of the whole mess. That or you'd be very limited in terms of how thick your overall plate could be in order to achieve proper through-hardness by quenching. Something like 50mm max.

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One does have to ask the question, what is such a steel sandwich supposed to achieve that a steel-rubber-steel or steel-explodium-steel sandwich won't do better and lighter?

I suspect it was one of many alternative armor technologies that fell by the wayside owing to the absolute performance dominance of reactive armors.

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DHA and THA was developed in the 1970s/1980s in order to improved TE against KE rounds. Reactive armor is not a suitable alternative in that role.

 

Given that there are standards (e.g. MIL-A-46099C for DHA) for such steel, it is very likely that it has been adopted in some shape or form in certain applications.

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2 hours ago, N-L-M said:

One does have to ask the question, what is such a steel sandwich supposed to achieve that a steel-rubber-steel or steel-explodium-steel sandwich won't do better and lighter?

I suspect it was one of many alternative armor technologies that fell by the wayside owing to the absolute performance dominance of reactive armors.

Yet another victim of the "everything is NERA/ERA issue" :rolleyes:

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Quite likely, yes.

I buy that THS more thickness- efficient, but tanks don't seem to have dimensional constraints as much as they do weight ones. The very wide array of very wide skirt options for tanks seems to suggest that weight efficiency is the more pressing concern.

 

As time goes on we see more and more that pretty much everything is a reactive sandwich of some sort, with the exception of armor solely optimized for dealing with rigid KE penetrators, where ceramics shine in the role of shattering them.

 

Unless the design optimization has very extreme constraints in some places and not others, there's no good reason to not bring your A-game design practices in terms of using the most efficient solution to every part of it, and unless you possess some magic secret sauce nobody else does, chances are the optimizations converge on a local maximum in the design space.

And indeed we see pretty much everyone doing more or less the same thing, with individual flavors varying based on externally set requirements (like extremely low collateral damage ERA for the German Puma).

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On 1/28/2021 at 1:13 PM, Toxn said:

I'm not sure why you'd bother rolling it - it would severely limit the amount of hardness you could give the high-hardness plate at the centre of the whole mess. That or you'd be very limited in terms of how thick your overall plate could be in order to achieve proper through-hardness by quenching. Something like 50mm max.

 

Rolled metal laminates are less limited in thickness than explosively bonded ones.  On the other hand, explosive bonding (at least if you do it right) has a stronger bond between the layers, and allows the bonding of highly dissimilar metals (like steel and aluminum).

One thing that the designer must be very careful with when making double or triple hardness steel laminates is that the different sorts of steel laminated together have the same martensite start temperature even if they do not have the same final hardness.  The martensitic phase transformation has a small, but extremely rapid volume change (and actually this is why katanas are curved back like that; when the edge transforms into martensite it actually gets slightly more voluminous and bends the entire blade backwards).  If the two plates don't transform simultaneously they can shear apart.

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21 hours ago, N-L-M said:

Quite likely, yes.

I buy that THS more thickness- efficient, but tanks don't seem to have dimensional constraints as much as they do weight ones.


Perhaps they are used in conjunction; DHA/THA and (N)ERA to get the most resistance to all threats at a reasonable volume? Is/would it be cheaper to make these steels than some fancy ceramics? 

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On 1/28/2021 at 9:13 PM, Toxn said:

I'm not sure why you'd bother rolling it - it would severely limit the amount of hardness you could give the high-hardness plate at the centre of the whole mess. That or you'd be very limited in terms of how thick your overall plate could be in order to achieve proper through-hardness by quenching. Something like 50mm max.

 

MIL-A-46099C limits the thickness of DHS to 14mm, meanwhile MIL-DTL-32332A limits it to 16mm.

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19 hours ago, Lord_James said:


Perhaps they are used in conjunction; DHA/THA and (N)ERA to get the most resistance to all threats at a reasonable volume? Is/would it be cheaper to make these steels than some fancy ceramics? 

 

 

Depending on exactly what grade of steel it is, it may be weldable, or at the very least it could be riveted and used to carry loads.  Even extremely high hardness steel is a much better structural material than any ceramic, which is purely dead weight from a structural standpoint.

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Does anyone know for sure how much better Triple Hardness armor was supposed to be over Dual-Hardness Armor or RHAr?  Janes' Technology of Tanks and Hazell's book put DHA as being equal to 1.7-1.8 it's own thickness in RHA, but aside from uncited numbers posted on various forums I haven't seen anything definite.

 

Also this company apparently has been working with Dual-hardness steel:  https://diamondage.org/advanced-alloys/

 

Not sure they've put anything out (or how much faith to put in their claims) but it at least seems interesting. 

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1 hour ago, A_Mysterious_Stranger said:

Does anyone know for sure how much better Triple Hardness armor was supposed to be over Dual-Hardness Armor or RHAr?  Janes' Technology of Tanks and Hazell's book put DHA as being equal to 1.7-1.8 it's own thickness in RHA, but aside from uncited numbers posted on various forums I haven't seen anything definite.

 

Also this company apparently has been working with Dual-hardness steel:  https://diamondage.org/advanced-alloys/

 

Not sure they've put anything out (or how much faith to put in their claims) but it at least seems interesting. 



I suspect that it's gotten better over the years.  The numbers I've seen in older sources are lower, and the number I've seen in more recent sources are considerably higher.

A while back there was a link to a monolithic high hardness steel that was 2x effectiveness over RHA.  I suspect that anything that hard can't be made in particularly thick sections, and is likely impossible to weld, but it does seem that there has been significant improvement in steel armor technology.

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  • 1 month later...

https://apps.dtic.mil/dtic/tr/fulltext/u2/383336.pdf

 

“Development of heat-treated composite steel armor” (July 1967)
 

I stumbled upon this while looking for something else, but it contains a bit of information on dual hardness steel (as well as some triple and quadruple layered steels), and some of the techniques they were using at the time. 

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