"Face Hardened Versus Homogeneous Armour" Topic

I don't know a thing about the metallurgy, but I was always impressed looking at the King Tiger at Aberdeen Proving Grounds. It had been hit about a dozen times by some weapon (I'd guess probably a 75mm gun). At the impact points the armor had just turned into a plastic and flowed like modelling clay, leaving divots in the armor the size of a man's fist. It just looked like you had a slab of clay and forced your fist into it and the clay had oozed away from your fist. And, of course, the remaining divot and displaced metal was still hard as steel :)

check out the following sites and explanations.
link
link

found plenty more just my doing a search with the subject: face hardened armor

Uncapped AP has trouble with face hardened armor while capped AP does better against FH than homogenous.

You might find something on Scribed for free or order TM 9 1907 from link

This has tables comparing penetration of US shells vs homogenous and FH.

AFAIK, FH armour was fielded only on the nose plates of some Pz IIIs and IVs. The kinds of weapons likely to be fired at these are, in my opinion, not likely to have their expected performance strongly influenced by whether the target is FH or MQ plate. For example, a 2-pdr shot fired at a 50 + 20 Pz III hull front would not go through whether the front plate was FH or MQ, whether firing AP, AP HV, APC or APCBC. A 6-pdr, at most combat ranges, and with similar disregard of ammunition natures, would.

Unless your rules already have such fine distinctions as the difference between AP and AP HV, the interaction of capped shot with impact angle, and distinguish armour thicknesses to closer than the nearest 10mm, I would;t bother to distinguish between FH and MQ.

All the best,

John.

Isn't this driven by the level of detail in your rules?

It seems to assume that you differentiate hit locations.

The issue is probably a NON-issue for gaming because of the variety of issues facing German armor manufacturers. Face-Hardened steel was used in various manufacturing methods for both the Pz III and Pz IV, usually in the spaced armor role on those models. It was also used in some instances on the Panther, Tiger and King-Tiger IF they had the metal to work with and the ability to get it face-hardened prior to welding the hull or turrets together. Also, some of the plates might have been face-hardened while others were not – on the same vehicle. This is from a 1956 book written in German which documented tank production and has some information on a few of the issues facing German armor producers throughout the war.

I agree with the above-comments – it should vary more with the level of detail you are trying to replicate in your rules. There are a ton of on-line resources documenting the difficulty in tracking down which tanks had and which tanks did not have face-hardened armor. One account I read had the British testing weapons against face-hardened armor on a Panther, and on homogeneous armor on a different Panther – at the same testing grounds. So, unless I read it wrong or am not remembering it correctly, the vagueness on which tanks did and which did not have face-hardened armor is going to be very difficult to ferret out without getting into a level of detail which you probably don't want to introduce into a game. Then again, your view may vary widely from my ideas.

In reading the links – like most things – there are some levels of abstraction which are best left in the rules as abstractions rather than trying to become the next "Phoenix Command" of tank combat set of rules and being MORE detail oriented than Tractics II or some other hyper-focused sets of rules on armor penetration over other mechanics.

Best of luck in your endeavors!

The Pz III and Pz IV had the turret front, the nose and driver's plate FH. These were sometimes protected by another homogeneous plate that acted to decap AP capped projectiles.
The lower nose plate of the Panther D and A supposedly was FH.

While Panzer War is the most detailed game around we don't bother with face hard. I feel you would get into a guessing game of choosing the right ammo for a situation were the tank gunner would not know the composition of enemy armor plate.

I'm actually a metallurgist and have done a little work in developing alloys for use as armor plate. While there are certainly difference in penetration behavior depending in the relative properties of the armor and the penetrator, the fact is that any piece of metal has variation in properties tfronlocation to location even in a single plate. Couple this with variations in the projectile and the further randomness on the battlefield, particularly angle of impact, and the differences between face hardened and Homogeneous Plate are going to get swamped. I certainly wouldn't worry about them in a game sense.

As I understand it: the Germans used face-hardened armor because it worked well against Soviet AT ammo (not capped), and that's where most of their panzers fought most of the time. However, it was actually a detriment against western (U.S. and U.K.) guns, which used APC and APBC ammo a lot.

donlowry wrote:

As I understand it: the Germans used face-hardened armor because it worked well against Soviet AT ammo (not capped), and that's where most of their panzers fought most of the time. However, it was actually a detriment against western (U.S. and U.K.) guns, which used APC and APBC ammo a lot.

Not my understanding -- I believe the Sovs capped their AP rounds earlier than the Brits, and the US used caps right from the start of their involvement.

The 2-pdr has a reputation for failing against FH armour, but this was probably thanks to the thickness of the armour often being beyond the 2-pdrs ability to penetrate anyway, and the fact (attested in Perret's "Valentine", I think) that the tracer element often broke off on impact, so giving the impression of a ricochet even when the shot had penetrated.

All the best,

John.

Not my understanding -- I believe the Sovs capped their AP rounds earlier than the Brits,

My understanding is the Sovs did have ballistic caps that streamlined the shell as they used flat nosed or beveled/flat noses with various slots. These to penetrate sloped armor better, but I don't recall any of their common rounds with AP caps.

I am sure that John will correct me, but i thought that FH tended to break up rounds which were overmatched, even if they could theoretically penetrate – eg 40mm gun vs 50mm plate, whereas overmatching rounds tended to fracture the plate.

Fairly good summary of the pros and cons of FH can be found at GvA:

link

…And thanks to BuckeyeBob for posting that link to the CM forum – I got a real nostalgic chuckle from reliving one of Lorrin's many manic threads !

On checking the few sources I have on Soviet AP ammunition (some metallurgical reports from the Watertown Arsenal) it looks as if Mobius is right. I still have some residual difficulty getting my head around the idea of having a ballistic cap without a piercing cap. If only there was a good authoritative source available on Soviet WW2-era ammunition…(sigh).

I would suggest that the thing a treadhead detail-fiend might want to model is the phenomenon of shatter gap, and this seems to have occurred in WW2 notably with:

British uncapped 2-pdr AP and AP HV
Early US 76mm APCBC
Early Soviet 45mm and 76mm APHE

I would not bother so much with "what is the interaction between FH armour and piercing caps", because the thing that matters, as I understand it, is whether the force produced by the striking velocity of the shot exceeds the strength of the projectile to withstand -- I believe that projectile shatter in steel projectiles starts at impact velocities of about 750 m/sec. Piercing caps help delay the onset of shatter, but, as shown by the case of US 76mm, aren't necessarily sufficient if the projectile isn't strong enough. Likewise, there is no reason a fast-moving projectile shouldn't shatter against MQ armour.

The tactical effect of shatter gap is to give the range vs penetration curve of a projectile an odd shape -- normally one expects penetration to decrease monotonically with range, but instead you will see an increase in penetration down-range as the projectile falls below its shatter velocity. Shatter does not necessarily mean shot failure, as "shattered penetrations" are possible.

If I knew a good deal more about metallurgy, impact dynamics, and in particular adiabatic shear stress banding, I might be able to account for these pehnomena better. However, for wargaming purposes (2-pdrs against late Mk IIIs, 76mm APCBC against Tigers and Panthers, early Sovs being overrun in Barbarrossa) other factors should already give the Germans such an edge that including shatter gap adds little, unless you are the sort of wargamer who likes "+1 for being German" rules.

All the best,

John.

"+1 for being German" rules

Indeed.

I actually have an old set of wargames rules (1984) called GI Commander that has quite detailed optional rules for Face Hardened armour. At 74 pages in a very small font I can't say I've ever attempted to play them though…

As Hornswagler's site says: "The Germans were faced with APC and APCBC from the Western allies only, not the Soviets, so their decision to use FH armour weakened their tanks against Western guns but strengthened them against Soviet guns."

so their decision to use FH armour weakened their tanks against Western guns but strengthened them against Soviet guns.

Not so fast. This had the opposite affect for the Tiger and Panther with homogeneous armor. The switch to capped ammo and HE filler instead of the solid core AP reduced the effectiveness vs. homogeneous armor by about 10%. Thus the Tiger and Panther received a benefit. The PZIV and StuG with the 8cm front homogenous armor instead of the 3cm + 5cm fronts also benefited.