Tuesday 8 May 2018

PzIII Armour in British Hands

I previously shared how the PzIII did in Soviet hands. In summary, the 30 mm plate proved far too brittle under fire from a 45 mm gun, shattering into pieces from just one hit. Curiously, British trials find the exact same thing.

Under attack from 2-pounder AP shot, the first projectile chips off the edge, but the second shatters the plate and causes severe cracks. When the remaining pieces are tested, they too crack into pieces after one or two shots with APC shells at 20 and 30 degrees. The British had more than just one hatch, however, and also observed the welding seams coming apart after the shots. The velocities matched those for 1200 yards in the test with AP and 1000 yards with APC. 


However, things get even more interesting after. In trials against a later model PzIII, one with 50 mm of front armour, the 2-pounder can get a shot through the front plate from 100 yards, although the projectile shatters. Interestingly enough, in Soviet trials, the 2-pounder only managed to penetrate the upper edge of the StuG's upper plate (also 50 mm thick) once from 100 meters. The testers were unable to reproduce this penetration from 50 or 100 meters. The Soviet conclusion is that the 2-pounder cannot penetrate 50 mm of armour at any distance, whereas the British are content with its ability to penetrate the German tank from 100 yards. The British also establish that the 2-pounder can defeat a PzIII from the front from 300 yards with HV ammo, but the Soviets didn't have any available.

36 comments:

  1. These are really interesting reports. I'd read lots about German armor being bad at the end of the war which I would expect with the economy collapsing. It appears they had problems all along.

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    1. Samples of armour obtained by the Allies revealed that the Germans were scaling back on the amount of nickel used in armour as early as 1940. The German economy was not built for a drawn out war.

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    2. As a child I toured Climax Mine in Colo. which during WW 2 was the worlds largest producer of molybdenum. Driving up it looked like a God had come down and taken a bit out of Freemont Pass. This and a host of other mines were of such importance that mining engineers were blocked from going to war.

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    3. The Germans, too, put off the drafting of miners and similar critical skilled labour as long as they possibly could. Eventually they had to start replacing even those with slave labour but predictably that did output tonnages no favours...

      Not much you can do when a given raw material can't even be found in your territories in the first place (at least in sufficient quantities) ofc.

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  2. Contrary to what Peter S wrote, Ni was present in german armor plate as late as 1944/5 where needed (i.e. thick plating)
    The presence of absence of Ni or Mb is a poor proxy for high mechanical properties of steel.

    The reason why the british obtained penetration at short range while the soviets did not is also written in the report.

    2pdr A.P. HADFIELD SPECIAL FOR PROOF OF PLATE

    This lot of AP made by Hadfield (regarded as the best ammunition maker for R.N., too) would not be available to the soviets. It was expanded only on the prooving ground, and is of higher quality than service A.P.

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    1. "Where needed" and "thick plating" are very subjective terms. All the Western Allies and the USSR noticed is that nickel disappeared. If the Germans reserved it for some extra special quality of plate that nobody ever found on the battlefield, that's their problem.

      As for Hadfield's ammo being better than field grade, that's your opinion once more. British penetration tables give the distances for 50 mm plate as 200 yards for regular and 400 yards for HV ammunition, 100 yards greater for both quantities than obtained in the trial with Hadfield's shot.

      https://imgur.com/hVESBW3

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    2. Is "high mechanical properties of steel" some alternative technical term for "shatters spectacularly when shot at"?

      Also you contradict yourself in the very first paragraph. If nickel is "needed [for thick plating]" then how can it simultaneously be "a poor proxy" for something else...?

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    3. The british- unlike the germans- fabricated special proof shot and the report quotes those beeing used. Penetration tables are often based on these. These may or may not agree with field trials.
      Special proof shot was service accepted for projectiles of every heat forming a lot. Service AP were selected from multiple heats forming one lot, so QC was tighter, too.

      Ni was present in thick plates 1944. Presence of it was related to section thickness of armor plate, not to "higher quality".

      The strength of the plate is primarely related to the heat treatment.

      The sophisticated heat treatment is the reason why german AP was superior despite the absence of Ni and Mb in mid ww2 shell steel while US AP had plenty amounts of Ni and Mb but exhibited inferior mechanical properties when compared to german. German midww2 shell steel was even leaner in alloy composition than soviet shell steel.

      the 30mm HHA PzIII side plating was not intended to be shellproof against overmatching calibre.

      Notice also that the PzIII exhibited superior resistence to 2pdr APC. Actual penetration range was only 100m-200m for 50mm and 1000yds for 31mm german RHA. UK performance table as reproduced in SUPP 6/910 p.63, Tab.8 (originally classified SECRET) give a penetration of 50mm british RHA at 30° and 1000yds and 38mm british RHA at 30° and 2000yds range for the 2pdr firing capped AP. So You might find ductility of german RHA wanting but resistence to penetration was actually very much superior and that translated into 2pdr penetration only at relatively close range rather than very large range as was the case with british MQ.

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    4. "The strength of the plate is primarely (sic) related to the heat treatment."

      I'm sure this is why various alloying elements were such an important strategic resource and everyone did their level best to come up with combinations that minimised the need to import the damn things...

      Also those late-war "thick plates" sometimes abruptly came apart in very dramatic fashion under impact as we have previously discussed at (considerable) length, so yeah. The evidence rather implies that German "sophisticated heat treatment" wasn't quite the Philosopher's Stone you like to pretend it was at least insofar armour plate went.

      And I'm tolerably sure armour plate in general is not supposed to *shatter* when shot at irrespective of thickness and overmatching. As pointed out in the previous discussion this stuff isn't the ablative ceramic inserts of modern body armour...

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    5. Mind if I ask whether or not your "tolerably sure armour plate in general is not supposed to *shatter* when shot at irrespective of thickness and overmatchiing" does also extent to soviet armor?
      Soviet MZ-2 /Is-8 armor (T34 High hardness standart armor) was shattered thoroughly by overmatching 76mm Br-350A impacts -at fairly low velocities, too, and failed to be of minimal quality for acceptance. What did the soviets do? They just ordered the requirement to resist overmatching impact to be deleted from the acceptance criteria. Such armor was procured and accepted in the 100.000´s ts.

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    6. As I already illustrated to you every single time you bring this up (which seems to be in every other post), this alleged weakness does not show up during analysis of knocked out tanks on the battlefield, whereas is absolutely does for Germans.

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    7. And as I already responded, You comnpared apples with oranges:
      A) soviet definition of poor plate behaviour required >3 cal diameter holes, or it would be considered "fair". british or german definitions had a much tighter border <2 cal diamter hole, US even 1.5 cal.
      B) the MZ2 failed vs Br350A (uncappedAP). These shells break up on impact. The 2pdr used here shattered, too against the PzIII armor.
      T34 was attacked by capped AP on the battlefield, and these shells, having superior penetration to the inferior, uncapped soviet domestic AP, will cause smaller diameter holes because they usually stay intact and don´t break up.

      Different failure mechanics. But I don´t expect You to understand the basic fundamentals of armor protection given Your track record on these matters...

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    8. Yes, I'm sure all the British, American, and Soviet engineers whose findings I post here have no understanding of anything, you are the only one who is qualified to make any statements and your opinion is equal to their findings.

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    9. Well at least we can agree that You don´t understand these things because You keep comparing apples with oranges.

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    10. No, we can agree that you have an over-inflated opinion of yourself.

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    11. Peter Samsonov, the mistakes shown here, Your inability to reflect the issues of this trial and Your vast ignorance of the differences in plate-projectile interaction mechanics are Your failing, not mine.

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    12. Yup, it's just that American, Soviet, and British engineers happen to agree with me, and not you. Funny how that worked out.

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  3. You don´t understand nor comprehend armor metallurgy, so my advice would be first to aquire some basic knowledge.

    Alloying determines the response of a cast to primary and secondary thermal and mechanical treatments, they do not predetermine the strength of the material.

    You can shatter all homogenious armor plate, it´s just a question of the type of attack required to obtain this result. German armor was specifically heat treated with the aim to hit the 1st ductile-brittle transition range for optimal ballistic protection against intact projectiles, the type of projectiles Germany was procuring during ww2.

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    1. Pray tell how is the plate shattering on first actual hit supposed to be acceptable material performance by ANY standard whatsoever? And the 2-pounder wasn't even a spectacularly powerful gun.

      You can posture all you want about your supposedly superior knowledge (and pretend stating the obvious somehow demonstrates such superiority) but that does nothing to change the blunt fact *the plate broke to pieces* which I can only assume wasn't exactly what the German military ordered.

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  4. Plus, one should not forget that the PzIII plate tested here was a FACE HARDENED plate, not homogenious. It faired extraordinary well if compared to aequivalent thickness british FH plate. The 2pdr firing APCBC was rated to defeat 31mm british FH (carburized plate) @30° at more >2000 and <2500yds, which is, as You might recognize, twice the range the PzIII plate failed.

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    1. It also fell apart on the first solid hit. I'm not familiar with a criterion of armour-plate performance by which that would be considered "faring extraordinarily well"...

      Last I checked proper armour was supposed to fail by getting a relatively clean hole punched through it, not by completely falling apart like so much glass. That the shell that caused said unsightly fragmenting *also* shattered seems like a rather cold comfort given how the plates form a load-bearing structural element...

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    2. To reiterate:

      FACE HARDENED PLATE CANNOT FAIL BY DUCTILE HOLE FORMATION

      So difficult to understand? FH cannot fail in a clean ductile holing event, that failure mode is only possible for RHA and Navy KC, and only when the ductile back section of the decrementally hardened KC plate is considerably larger than the attacking projectile (i.e. 15cm APC vs 25cm KC plate, which I own the trial reports of). FH plate will be rigid until it is defeated by attack, at which point it will give in a rapid way either by plugging or discing. Cracking is frequently associated with surface hardened FH plate when attacked by overmatching projectiles (which 40mm vs 30mm plate, actually is true here). What counts is that the FH plate is of superior ballistic resistence compared to MQ or british FH.
      Yes it will fail badly, but it will fail at shorter range to the same threat, and considerably thicker armor would be required to meet this shorter range protection with MQ plate. If ductile hole character were the only criterium of good armor, then everybody would have used mild steel instead of FH / HHA/ RHA armor.

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    3. Right, so what's your excuse for Soviet 30 mm armour plates withstanding hits from 45 mm AP while German plates of the same size shatter into pieces? A wizard did it?

      I already showed you many, many sources that say the opposite of what you claim. The British say, time and time again, that comparable German armour is *inferior* to their IT70 and IT80 standards.

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    4. Well "superior ballistic resistance" is certainly a fine thing and I think we can all agree the way about half of the shells shattered against the plate without achieving much is a perfectly satisficatory outcome.

      The plate itself progressively breaking to smaller and smaller pieces on about every other hit, OTOH, is *not* regardless of how you try to spin it. The intented design of the metallurgy is simply irrelevant here; THAT SHOULD NOT HAPPEN PERIOD.
      Again - this is not ballistic-vest ceramic inserts.

      While your explanation of the operating principles is interesting it changes nothing about that naked truth and has the unbecoming whiff of a red herring about it.

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    5. Another red herring is presented by Peter. If he thinks that the opposite is true, i.e. in the case of discussion that an undermatching FH plate can be defeated in ductile mode than he is even more depart from the physics of this world than anybody could ever imagine...

      It´s not enough to take a result, You have to understand what factors were involved in a given result.

      F.e. WHY, for example, do You fail to reflect upon the fact that the PzIII plates were removed with help of a cutting torch? How does a secondary heat treatment followed by an aircool does to a surface hardened plate, which is Thermo-mechanically treated to fit a specific condition?

      Do You admit that You failed to reflected about it because You don´t comprehend these problems?

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    6. Are you SERIOUSLY trying to excuse the structural failure of the entire plate of, what, about 24"x18" if I'm reading the report correctly, by the localised effects of the cutting torch on the edges of it?
      Get out of here.
      I was actually taught something about metallurgy and tempering steel years ago in vocational school and that has "bullshit excuse" written all over it. Heat doesn't conduct to THAT degree in steel.

      I also like how you seem to assume the British testers knew nothing at all about any of that which is absurd right in the face of it. The principles of this have been known to, if for the most part only patchily understood by, blacksmiths for some three thousand years and graduated into a real science during the Industrial Revolution.

      Not to mention there's no shortage of German plates still solidly in place in the original vehicles shattering under fire, as we have previously discussed.

      Short form: these plates were not performing acceptably by ANYONE'S standards - I'm giving the Germans more credit than assume their official bar was this low - no matter how desperately you try to deny it and red-herring into factual irrelevancies.

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    7. Not to mention that the Soviet tests were against a hatch that was not cut up any further, so the heat excuse does not apply.

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  5. *Plate shatters into pieces on impact*
    British engineer: this plate is too brittle and below our standards.
    Soviet engineer: this plate is too brittle and below our standards.
    American engineer: this plate is too brittle and below our standards.
    Critical mass: actually none of you know anything about metallurgy and it's actually really good because I said so.

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  6. When the 2pdr is expected to penetrate 30mm britih FH plate at distances larger than 2000/2200 yard and the german PzIII FH plate can only be perforated at 1000 yard, yes, then I´d argue that it is ballistically superior. Why? Because it is vulnerable to the same threat at only half the distance.

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    1. Where are you getting any of these figures from?

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  7. SUPP9/610 official penetration tables of 2pdr gun firing A.P.C.B.C.

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    1. You're comparing penetration of British armour with APCBC to penetration of German armour with AP.

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    2. Let's compare apples and apples:

      https://i.imgur.com/hou1xFL.png

      1600 yards to penetrate 32 mm of British armour with HV AP.

      https://i.imgur.com/hVESBW3.png

      1700 yards to penetrate the same amount of German armour with HV AP (measurements of captured tanks show that the sides were usually 31-32 mm thick rather than the nominal 30 mm).

      So a 100 yard difference in British favour instead of the 1000+ yard difference in German favour you claim. In addition, the German plate shatters into pieces while the British one does not, which is why the British concluded that their armour is superior.

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    3. I have given my answer to that in a memo supressed by You. You use the wrong tables, of course, and a different obliquity criterium. Not that You want to take care...

      Note that both, capped and uncapped 2pdr A.P. were fired on 31mm plates at 20° with a specific velocity.

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    4. The angle of attack in the document is 20 degrees, yes. The velocity is specific, yes. What's your point? The plate never once managed to resist the 2-pounder AP, which is why the British started angling the plate more to figure out at least something about the German armour other than it's really brittle and breaks up catastrophically.

      What I don't understand is why you used the data for APCBC and are now claiming that I'm the one using wrong tables.

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  8. Dealt with a lot of armor plate in my time working as a machinist, and no way in hell is a touch of "hot wrench" going to radically affect the face hardening.

    You'd have to get the whole chunk of armor pretty fucking hot to affect any face hardening.
    At best the effect will be very localized, and easily demonstrable. .

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