Armor quality of Panzer III and IV

Discussions on the vehicles used by the Axis forces. Hosted by Christian Ankerstjerne
critical mass
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Re: Armor quality of Panzer III and IV

Post by critical mass » 12 Feb 2019 12:03

no troubles here...

Avalancheon
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Re: Armor quality of Panzer III and IV

Post by Avalancheon » 18 Feb 2019 01:24

critical mass wrote:
12 Feb 2019 12:03
no troubles here...
CM, have you ever read these articles about the Panzer IIIs armor? Why would German FHA plate perform worse than Soviet HHA plate? We know that HHA was inferior against capped projectiles, but could it have been superior against uncapped projectiles?

http://tankarchives.blogspot.com/2014/0 ... rmour.html
http://tankarchives.blogspot.com/2014/0 ... steel.html

critical mass
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Re: Armor quality of Panzer III and IV

Post by critical mass » 20 Feb 2019 20:29

The FD analysis is not a normal HHa plate, but used for normal hardness RHA.
I don’t see spalling on the back of the german plate. It looks to me that Sampsonov whishfully reads things into the photo which are not supported by evidence. The plate failed by cracking, which leads to variable results in ballistic resistance, however, neither projectile fragments nor plugs were thrown from the back. So the only failure here is the prominent, lateral cracking. How much more velocity would be required to throw a plug is unknown. It’s only safe to say that the velocity was below the limit of the plate.
Cracking can be a result of tuning effects, the German plates are not tested to resist blunt headed AP, used to test soviet plates...

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Re: Armor quality of Panzer III and IV

Post by Avalancheon » 21 Feb 2019 05:20

critical mass wrote:
20 Feb 2019 20:29
The FD analysis is not a normal HHa plate, but used for normal hardness RHA.
A 30mm thick plate at 460-444 BHN is pretty damn hard. You're saying the Soviets didn't use an HHA plate in the test?

http://tankarchives.blogspot.com/2014/0 ... rmour.html
critical mass wrote:
20 Feb 2019 20:29
I don’t see spalling on the back of the german plate. It looks to me that Sampsonov whishfully reads things into the photo which are not supported by evidence. The plate failed by cracking, which leads to variable results in ballistic resistance, however, neither projectile fragments nor plugs were thrown from the back. So the only failure here is the prominent, lateral cracking. How much more velocity would be required to throw a plug is unknown. It’s only safe to say that the velocity was below the limit of the plate.
Yeah, the claims of spalling in the plate can't really be corroborated by anything observed in the test itself. Thats one of the problems TankArchives has as a writer. He expects to see a certain thing so strongly that he convinces himself that he saw it, and then he asserts that his hallucination is a fact supported by the tests.

Its remarkable just how often TankArchives subconscious opinions leak into the reports he translates. Its a really glaring example of an 'unreliable narrator.'
critical mass wrote:
20 Feb 2019 20:29
Cracking can be a result of tuning effects, the German plates are not tested to resist blunt headed AP, used to test soviet plates...
Okay, so its a result of fine tuning. The Soviets required their plates to withstand 45mm domestic AP shells at 0 degree obliquity. In this specific criteria, they were clearly superior to German plates. No ifs, ands, or buts about it...

you've pointed out before that Soviet AP shells suffered from a soft and brittle nose. Do you know whether the plates would have done as well against an AP shell with a properly hardened nose, something like the 2 pounder AP?

critical mass
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Re: Armor quality of Panzer III and IV

Post by critical mass » 21 Feb 2019 17:16

FD-5654 was NOT (!) high hardness armor. The analysis is a straightforward copy of 1894 period german Krupp Q420 (classic homogenious Krupp armor steel, relatively rich on alloys). In the soviet Union, FD-5654 was always treated homoegnious, low hardness in thicknesses up to 40mm. In thicknesses of 13mm, FD-5654 also received face hardening (flame surface hardened), but not in 30mm. The production designation of this material was 6-PSK, and it occurs in many pre-T34 tanks.

In this thickness range FD-4654 is a better proxy for face hardened armor plate, a roughly similar analysis but with less carbon. Or, MZ-2 may have been used if ballistic resistence of homogenious high hardness in this thickness was pursued.

I take it that FD-5654 was experimentally treated to high hardness in this case, which is perfectly feasable. But one should be aware that it´s experimental armor, which will qualitatively deviate from standart armor due to a change of specification hardness. Specifications for later high hardness implicate that standart low hardness 6-PSK plate would probably have failed here by lack of resistence to penetration.

In 1940, at the time of the A-34, the then still experimental Х-3 high hardness armor plate was specified to resist against the 45mm blunt headed shell at 0° at the following velocities:
45mm: 710m/s PSP and 680m/s PTP
40mm: 660m/s PSP and 625m/s PTP
35mm: 610m/s PSP and 580m/s PTP
30mm: 550m/s PSP and 525m/s PTP

The german 30mm plate had neither PSP (no projectile through) nor PTP (no bulge with star cracks or plug started yet) at 533.8m/s actual, so it would have satisfied soviet specifications -IF it wouldn´t have been for the prominent plate shatter failure! Soviet metallurgic development went into the slightly different, experimental MZ-2 HHA (I8-S and later, production designation: 8-S), which obtained the following ballistic resistence on the prooving ground (crosses, 30mm, 0°: PSP: 573m/s & PTP: 533m/s):
https://t34inform.ru/photo/Ar_01_11.jpg
Take notice of the thick black lines (triangles are 37mm, crosses is 45mm projectile drawing 0130 and circles is another 45mm APBC):
https://t34inform.ru/photo/Ar_01_06.jpg

MZ-2 also failed badly -in later tests- due to plate shatter when attacked by overmatching projectiles (T/D 1.5 or larger). However, unlike Pz III 30mm plate, which underwent plate shatter but prevented projectile passage, MZ-2 did fail by full projectile passage, associated with or without plate shatter.
One might ask, why then did they not use the Izhor FD-5654 armor, which resisted so well up to 562m/s, much higher than the experimental MZ-2? Well, it was experimental armor, unsuited for mass production requirements due to the demand of high alloy quantities of scarce chromium and nickel as well as careful controll of the heat treatment times. The trial therefore does testify that the soviets could produce good quality plate when extra care was taken at hand.
you've pointed out before that Soviet AP shells suffered from a soft and brittle nose. Do you know whether the plates would have done as well against an AP shell with a properly hardened nose, something like the 2 pounder AP?
The 30mm face hardened plates were approx. equal to british MQ armor against 2pdr AP but considerably better than british FH armor against capped 2pdr APC, which shattered against this plate as if it had no cap at all.

Avalancheon
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Re: Armor quality of Panzer III and IV

Post by Avalancheon » 22 Feb 2019 05:22

critical mass wrote:
21 Feb 2019 17:16
FD-5654 was NOT (!) high hardness armor. The analysis is a straightforward copy of 1894 period german Krupp Q420 (classic homogenious Krupp armor steel, relatively rich on alloys). In the soviet Union, FD-5654 was always treated homoegnious, low hardness in thicknesses up to 40mm. In thicknesses of 13mm, FD-5654 also received face hardening (flame surface hardened), but not in 30mm. The production designation of this material was 6-PSK, and it occurs in many pre-T34 tanks.

In this thickness range FD-4654 is a better proxy for face hardened armor plate, a roughly similar analysis but with less carbon. Or, MZ-2 may have been used if ballistic resistence of homogenious high hardness in this thickness was pursued.
In order to provide a scientific control for the German FHA plate, the Soviets used an RHA plate as a reference? Weird. I wouldn't have guessed that it would make a better proxy than any of their other armors... Speaking of that, do you know whether the FD 5654 armor was ever used in any tanks? It certainly offered superior protection compared to the standard MZ-2 armor.
critical mass wrote:
21 Feb 2019 17:16
The german 30mm plate had neither PSP (no projectile through) nor PTP (no bulge with star cracks or plug started yet) at 533.8m/s actual, so it would have satisfied soviet specifications -IF it wouldn´t have been for the prominent plate shatter failure! Soviet metallurgic development went into the slightly different, experimental MZ-2 HHA (I8-S and later, production designation: 8-S), which obtained the following ballistic resistence on the prooving ground (crosses, 30mm, 0°: PSP: 573m/s & PTP: 533m/s):
https://t34inform.ru/photo/Ar_01_11.jpg
Take notice of the thick black lines (triangles are 37mm, crosses is 45mm projectile drawing 0130 and circles is another 45mm APBC):
https://t34inform.ru/photo/Ar_01_06.jpg
That an interesting way to look at it. Even though it sustained massive cracks, the German FHA plate didn't technically fail because it stopped the shell. It just did so in a much more degraded state than the FD-4654 armor. Clearly, FHA is no good for multi-hit protection near its ballistic limit.
critical mass wrote:
21 Feb 2019 17:16
MZ-2 also failed badly -in later tests- due to plate shatter when attacked by overmatching projectiles (T/D 1.5 or larger). However, unlike Pz III 30mm plate, which underwent plate shatter but prevented projectile passage, MZ-2 did fail by full projectile passage, associated with or without plate shatter.
One might ask, why then did they not use the Izhor FD-5654 armor, which resisted so well up to 562m/s, much higher than the experimental MZ-2? Well, it was experimental armor, unsuited for mass production requirements due to the demand of high alloy quantities of scarce chromium and nickel as well as careful controll of the heat treatment times. The trial therefore does testify that the soviets could produce good quality plate when extra care was taken at hand.
I know about the tests with the MZ-2 armor, and how badly they failed against 76mm AP. But I've never heard about it failing against 45mm AP. It sounds like HHA plates were even worse against overmatching shells than FHA! CM, do you have any more info about those tests with the 45mm AP?

critical mass
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Re: Armor quality of Panzer III and IV

Post by critical mass » 22 Feb 2019 10:35

I have to add a correction.

Apparently, when MZ-2 was taken into production, updated specifications, different from the earlier experimental ones were issued.
The details are to be found here:
https://t34inform.ru/doc/1940-07-27_Armor_TU.html

For the problem at hand, the specification velocity of PTP and PSP was further lowered from 525 and 550 m/s in the project aim stage to 510-515 (PTP) and 530-535m/s (PSP), respectively, in the updated production specification, as far as 30mm MZ-2 plating at 0° impact vs 45mm APBC was concerned. The 30mm FH Pz 3 production plate was above soviet specification velocity for acceptance of their production high hardness MZ-2 (i8-S) armor (510m/s PTP and 530m/s PSP).
To put it in a prospect, the soviets also asked Mariupol to study their own new MZ-2 high hardness armor against alternative products. Interestingly, MIZ and FD-7954 were choosen, as these were standart armor steels, unlike the experimental FD-5654 re heat treated to high hardness. At this point, the Mariupol plant reported the following resistence of MZ-2 vs 45mm APBC (drawing 013) at 0° following field trials:
50mm: 715m/s PTP, 730m/s PSP
45mm: 700m/s PTP, 720m/s PSP
40mm: 640m/s PTP, 660m/s PSP
35mm: 600m/s PTP, 620m/s PSP
30mm: 490m/s PTP, 510m/s PSP
Compared to MZ-2, the medium hardness standart RHA MIZ exhibited 10% lower PTP and the alloy richer, intermittent quenched, experimental FD-7954 5% lower PTP. Against both these products as well as against MZ-2 from 1940 period production, the 30mm FH exhibited a somwhat noticably superior ballistic resistence (>533.8m/s compared to 490m/s, 445m/s and 465m/s). You will not hear much about these comparative studies from Mr. Sampsonov.
Plates of 25 and 30mm thickness were then treated seperately from plates of 35 to 50mm, including. That´s because their thickness was low enough so that the resulting T/D ratio exhibited issues in overmatching 45mm impact, resulting in a rapid drop of ballistic strength (these plates were thin enough to not damage the 45mm APBC significantly, resulting in lower energy, adiabatic shear failures). Although details are lacking, evidence suggests that this problem was known. Very little armor in this thickness was made for the T-34. The A-32 design was changed in order to delete 25 & 30mm thick MZ-2 plates owing to inferior tests records. 25mm plates were only to be tested vs 37mm projectiles.

Shatter of plates in ww2 was one of the least liked plate failure modes. However, all failure modes can be utilized to work out a protection system. That´s how we use ceramic tiles today, they all do fail by plate shatter, yet they add ballistic protection. Its inferiority to an experimental FD-5654 plate was ascribed to plate shatter, not to failure in ballistic resistence. But then again, it´s an experimentally heat treated vs production plate comparison, or cherry picked oranges vs apples..

Notice also, Sampsonov claimed that 533.8m/s was the equal of 1600m downrange velocity for the 45mm mod. 32 gun. This statement is in conflict with soviet range table data from NII48, which drop below 500m/s at 1500m:
download/file.php?id=410744&mode=view

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Re: Armor quality of Panzer III and IV

Post by Peasant » 23 Apr 2019 17:30

Image

Interesting results. Previously I thought that Pz.III's were dead meat as soon as 75mm/6pdr guns came rolling in North Afrika, even the variants with add-on armour, but apparently they can still pose a challenge to them.

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Re: Armor quality of Panzer III and IV

Post by Yoozername » 24 Apr 2019 13:03

Here is a link to all 'resumes' of the APG tests.

https://worldoftanks.com/dcont/fb/document/tests_v6.pdf

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Re: Armor quality of Panzer III and IV

Post by Peasant » 24 Apr 2019 18:56

Yoozername wrote:
24 Apr 2019 13:03
Here is a link to all 'resumes' of the APG tests.

https://worldoftanks.com/dcont/fb/document/tests_v6.pdf
wrong link. this data is from Volume XI : https://worldoftanks.com/dcont/fb/docum ... es_v11.pdf

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Re: Armor quality of Panzer III and IV

Post by Avalancheon » 25 Apr 2019 06:14

This provides an interesting contrast to similar tests done by the Wa Pruf with the 75mm M3 gun. They determined that when the panzer IV was angled at 30 degrees, the glacis could only be pierced at a distance of 100 meters. The different results in the two tests can be attributed to the fact that the Americans used a spaced armor array, while the Germans used a layered armor array. The latter represents what the panzer IVs actually used: 50mm thick FHA base armor, and 30mm thick RHA applique armor.

One mystery is why the Americans were surprised at the cap shattering upon impact. What did they expect to happen?

Also interesting is a Watertown report from October 1943, about the composition of the panzer IVs armor. Apparently, the Germans were already beginning to reduce the alloy content in some of their thinner armor plates. WAL 710/539 specifically says: ''Of striking interest is the Si-Cr-Mo analysis, encountered for the first time in the subject armor. The reduction of the chromium and molybdenum contents indicates an attempt at conservation of those strategic alloying elements. The hardenability of the steel is maintained by an increase in silicon, a non-strategic alloying element.''

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Armor quality of Panzer III and IV Re: Cairo Tests

Post by Mobius » 25 Apr 2019 14:15

The Cairo Tests
To penetrate the given armor at 1000 yds the German 75mm shell must of been fired from the Sherman 75mm/L40 M3 gun and not the German 75mm/L24. So depending of ballistics it should strike somewhere 534-541 m/s when fired at 619 m/s.
cairo test.jpg
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Re: Armor quality of Panzer III and IV

Post by Mobius » 25 Apr 2019 14:24

Well, well well. Look what I found.
Looks to be a Russian reprint of German data.
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Re: Armor quality of Panzer III and IV

Post by L/24Stug » 27 Apr 2019 19:21

K. Gr. Patr. rot Pz penetration is the same between 100 and 1000 meters @ 685 m/s m.v.
You know, it is an indication of proyectile deformation-shattering.
But what does it really means? German proyectile tests required intact penetration, ready to burst beyond the plate. Does it means it is possible that it indeed penetrated thicker plates but not in bursting condition?

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Re: Armor quality of Panzer III and IV

Post by Peasant » 28 Apr 2019 12:33

Mobius wrote:
25 Apr 2019 14:24
Well, well well. Look what I found.
Looks to be a Russian reprint of German data.
In reality every shell design has a penetration maxima (german definition) beyond which all further increase in striking speed actually lowers the target difficulty(thickness ,obliquity ect.) that it can still defeat while remaining intact. Increasing velocity would only increase penetration by Soviet, US, British definition.
Don't forget that those curves are only the result of a mathematical model plotted as close as possible to the actual data from live tests. It seems that german engineers adopted a monotone function that described target resistance which can only grow with T/D.

Edit: the penetration chart for this shell cuts off after 700m/s so I guess they were aware of this fact.

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