A Question of Armor?

[PzKpfw 1]

<BLOCKQUOTE>quote:</font><HR>Originally posted by DanW:

Since this seems to be a relative gathering of experts, I'll toss my question out.

Dredging up my school days, it was my understanding that BHN was a function of how the metal was quenched. Wouldn't the subsequent welding operations of the German tank designs result in the parent material being significantly softer, in an annealed condition, rather then the initial hardness from the as quenched condition?

Dan W.<HR></BLOCKQUOTE>

I am no 'expert'what I have posted is from my limited understanding concerning the data I have available & from what I have learned from Robert & Jim over the years, they are experts though loathe to admit it .

The BHN given is the hardness from the plates used in the actual vehichles that the WA reports were on, and the actual plate BHN used for the penetration test results.

The British go into Poldi hardness & the softer & quenched aspects of German armor plate, in some detail in an paper I got from Jim, but its buried in boxes from the move, the paper also deals with face hardening practices.

If your interested I'd sugest getting a copy of the British report on German armor from 1946 I listed in the refrences in the previuos post, as it explains this all better then I can presently.

Regards, John Waters

[Paul Lakowski]

<BLOCKQUOTE>quote:</font><HR>Originally posted by DanW:

Wouldn't the subsequent welding operations of the German tank designs result in the parent material being significantly softer, in an annealed condition, rather then the initial hardness from the as quenched condition?

For the next ten days I'm still in my role as structural analyst, and these kind of discussions really float my boat.

Dan W.<HR></BLOCKQUOTE>

Dan I'll do some digging tomorrow cause there are several 'papers' on the ballistic resistane of weld joints in the Int.J.Impact Engng. Have you read any of these?

The one article I remember talked about 'Heat Affected Zones'

They showed that you could harden these areas to 500-600 BHN by some process, but it wasn't homogeneous through the depth of the weld.

As I recall the 'weld' ballistic resistance was much better than the 270-300 BHN plate resistance.

[Paul Lakowski]

Dan the paper is quite extensive and what I should do is scan and Email it to you but its 14 pages long , if your interested drop me an Email . The basics are as follows the base metal was 450-520 HV[10] and 6 different weld arrangements were tried., from basic soft weld [Austenitic weld 19% Cr 9% Ni =250-320 HV] to face hardened [ 30% Cr 4% C = 650-780 VH] and layered approach.. The ‘projectile’ was a 7.62mm API and the plates 500mm x 300mm and 6mm deep, so the results were velocity loss. The results were as follows

Start Velocity was 830m/s and plate was 6mm thick

<PRE>

Weld residual Velocity

Aust 600m/s

Aust/FH/Aust 0 m/s

FH/Aust 0 m/s

FH 800m/s

<PRE>

[PzKpfw 1]

Well digging through our move boxes I found a chapter of the British German Armor report (BIOS) dealing with German use of 'Flame Hardening' armor plate from 1940 - 1945, which I thought might be of interest here.

The Germans used flame hardening on all their 30 - 50mm AFV plates including the 60mm Panther nose. Flame hardening was considered ballisticly superior to cace hardening, in that flame hardened armor had 'less tendancy to flake'.

Their was an problem found with flame hardening in that flame hardened plate when FH of the whole plate was done, the plate could not be machined and the plate was also not satisfactory for welding, so the Germans used heat insulating & or water cooled copper sheilds to cover the plate edges.

Paul mentioned that Robert had brought up the Tiger II's, ball mg mount as an 'free edge', the Germans used flame hardening on all their bow MG mounts as well.

Live fire testing of the flame hardened plate was done in the following manner, 1 30mm plate was selected randomly from an batch of 50,(the 'batch' of 50 included plates from all casts, steel, & heat treated with no distinction by mm of plate) and tested vs 20mm AP, 50mm plates were tested vs 37mm AP.

After the test, the plate was fractured and the depth hardness measured. If the test plate failed, another plate was taken from the 'batch' and tested if that plate also failed the ballistic requirements the whole batch was scrapped.

Anyway the chapter deals with Face hardening, Electrical induction & High Frequency Hardening as well and is interesting reading.

Regards, John Waters

[DanW]

Gents,

Well if you guys aren't the experts, then I'd hate to find out who is. I'd also say that an expert isn't necessarily the one who knows everything, but rather someone who knows what he knows, and knows where to find the rest.

Returning to this idea of post-weld heat treating, I'm wondering if the penetrations that John Waters is talking about having seen in pictures, doesn't tie back into the heat affected zones near weld lines, rather then the free edge effect. I tend to agree that a turret edge should be well supported by the plate normal to it, as opposed to a gun mantlet which has a large cutout and no buttressing structure behind it.

To be honest I'm entering the seminary to study for the priesthood in a few weeks, and I don't have the time (or space) to begin accumulating a library of ballistics data. I do however have a keen interest in structural engineering and armor, so I'm game to learn whatever you guys are willing to teach me.

Thanks for the info. I found the various welds and filler material info interesting. I assumed that a 0 m/sec velocity meant that the weld defeated the round (i.e. no penetration)?

Dan W.

[Paul Lakowski]

I've bee asked my opinion of the accuracy of the armor penetration system, while the armor question [related to Tiger-1 front armor ] is still open to debate, I'd like to examine the Armor penetration system.

What is the game penetration value assigned the US 57mm APCBC ammo at 500-1000 yards and whats the value for the British 6lb APCBC round?

Whats the same game value for the 76mm APCBC ammo and German 75L48 gun @ 500 M & 1000 M range?

How did you deal with slanted penetration and the differing criteria for defining what is and is not a penetration?

[PzKpfw 1]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Paul Lakowski:

What is the game penetration value assigned the US 57mm APCBC ammo at 500-1000 yards and whats the value for the British 6lb APCBC round? <HR></BLOCKQUOTE>

US 57mm AP Penetration from Game data.

@ 0^

500ms - 91mm

1000ms - 78mm

@ 30^

500ms - 71mm

1000ms - 63mm

@ 60^

500ms - 39mm

1000ms - 36

UK 6Pdr AP Penetration from Game data.

@ 0^

500ms - 91mm

1000ms - 78mm

@ 30^

500ms - 71mm

1000ms - 63mm

@ 60^

500ms - 39mm

1000ms - 36mm

<BLOCKQUOTE>quote:</font><HR>

Whats the same game value for the 76mm APCBC ammo and German 75L48 gun @ 500 M & 1000 M range? <HR></BLOCKQUOTE>

76mm AP Penetration from Game Data:

@ 0^

500ms - 112mm

1000ms - 101mm

@ 30^

500ms - 89mm

1000ms- 82mm

@ 60^

500ms - 50mm

1000ms - 46mm

75L48 AP Penetration from Game Data:

@ 0^

500ms - 130mm

1000ms - 112mm

@ 30^

500ms - 100mm

1000ms - 90mm

@ 60^

500ms - 49mm

1000ms - 46mm

Regards, John Waters

[Paul Lakowski]

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1:

76mm AP Penetration from Game Data:

[PRE]

500ms 1000ms

@ 0^- 112mm - 101mm

@ 30^ - 89mm - 82mm

@ 60^ - 50mm - 46mm

75L48 AP Penetration from Game Data:

500ms 1000ms

@ 0^ - 130mm - 112mm

@ 30^ - 100mm - 90mm

@ 60^ - 49mm - 46mm

<HR></BLOCKQUOTE>

John are these LOS values cause Jentz reports

"Example : The penetrating ability of the 7.5cm Pzgr.39 fired from the Pak 40 at a range of 1000meters os 81mm at an impact angle 30°. Penetrating ability at this same range at 0°is 95mm ,45° is 50mm , and 60° is 32mm."...'Tank Combat in North Africa'.

Rgds Paul & keep up the good work

[guachi]

The question arises - what KIND of armor is being penetrated? Just because CM's numbers differ from what is in a book doesn't mean that EITHER of them is wrong. We would have to know the test conditions first.

Jason

[Jeff Heidman]

Wow, what a great discussion.

Nothing like something like this to keep me humble.

What is meant by the term "overmatching"?

Jeff Heidman

[PzKpfw 1]

<BLOCKQUOTE>quote:</font><HR>Originally posted by guachi:

The question arises - what KIND of armor is being penetrated? Just because CM's numbers differ from what is in a book doesn't mean that EITHER of them is wrong. We would have to know the test conditions first.

Jason<HR></BLOCKQUOTE>

the German test plate was 285 - 300BHN, US & UK test plate was 240 - 250 BHN, Soviet plate was 285 - 400BHN. They took that plate and shot it under ideal conditions at the ranges specified, giveing the penetration results given here @ 30^ etc .

Paul bah, I just copied it from the unit box nothing big.

I believe its LOS, but someone from BTS would have to respond on that.

Yes Jentz revised the data in Panzertruppen 2 to Wa Pruef data. I sent you the revised data in our E-mail.

Regards, John Waters

[Paul Lakowski]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Jeff Heidman:

Wow, what a great discussion.

Nothing like something like this to keep me humble.

What is meant by the term "overmatching"?

Jeff Heidman<HR></BLOCKQUOTE>

Overmatch means the target armor plate is thinner than the projectile diameter.

Armored steel has been shon to resist differently depending on wether the projectile is larger than the plate thickness.This is part of the 'confinement issue'. Modern long rod penetration studies are always done into targets 1.6 times the maximum penetration possible to avoid this problem in measurement.

In the case of hard steel they seem to suffer more and result in plate shattering and less resistance than simple RHA.