Monday 27 November 2017

T-34 Armour Research

January 25th, 1940

"
  1. When researching armour for 25-50 mm plates, the Ilyich Research Laboratory made the correct decision to explore highly hardened steel while preserving the necessary degree of ductility. Despite existing opinions that thick tank armour (40-75 mm) must have lower hardness (3.4-3.6 mm), the Research Laboratory developed hard armour (2.9-3.1 mm), finding a successful combination of alloying components, which gave the armour satisfactory ductility.
  2. The commission remarks that work on MZ-2 armour was done very thoroughly. Experience with HZ steel made from byproducts of ship armour manufacturing proposed by engineer D.I. Chizhikov in 1937 was applied, work on determining the optimal combination of elements (C, Ni, Si) for various armour thicknesses was performed, although the analysis should be confirmed for 30 and 35 mm thick armour.
    The process of smelting steel from byproducts of ship armour with minimal addition of nickel was developed. Work to establish the thermal hardening process was performed. Sufficient proving grounds trials were performed to present the type of steel to the commission.
    However, the commission remarks on the insufficient amount of laboratory work performed on the materials, especially microscopic analysis and fracture tests, with correlations established between armour quality and fracture test results.
  3. Let it be noted that, at the point of delivery of MZ-2 armour, it had already been used in the production of A-34 hull components, and has proven itself completely. Another positive note is that not one, but six plates were presented for delivery, which allows for more confident conclusions.
  4. Based on the results of trials, the commission concludes that MZ-2 steel demonstrates high resistance to shells and bullets when used in thicknesses of 40, 45, 50, and 25 mm against shells up to 45 mm in caliber inclusive, which is superior to tank armour of FD-4654, 4674, and 7634 types, as well as high quality HNM plates used by the AU to test shells.
    In addition to high resistance (PSP and PTP [rear plate intactness and complete penetration]) against blunt tipped 45 mm shells, both at normal and at angles, 40, 45, and 50 mm plates also showed good resistance against sharp tipped 2-01991 45 mm shells, which approached the resistance of surface hardened plates against this type of shell.
    Due to a lack of data against 37 mm ammunition, the commission could not perform a detailed comparison against other types of armour. MZ-2 plates also reliably destroy incoming shells. 40 mm thick plates and up do not allow a shell to penetrate with its HE chamber intact. 
  5. These excellent characteristics are achieved due to high hardness and satisfactory ductility demonstrated by 40, 45, and 50 mm thick plates against 37 and 45 mm shells. These characteristics (hardness and ductility) are the defining characteristics of MZ-2 steel. A simple heat treatment method ensures that production will be kept up to standards.
  6. From a cost standpoint, MZ-2 steel is very interesting, as it allows the production of tank armour, sufficiently hardened by additions of nickel and molybdenum, with minimal additions of nickel and use of ship armour byproducts. Existing types of tank armour, FD-4654, 7934, and even MIZ require a large amount of additional nickel and molybdenum.
The commission considers it necessary to task the Ilich Research Laboratory with the following work:
  1. Smelt MZ-2 steel with nickel and molybdenum from byproducts in such a way that additional nickel is not required.
  2. Explore other ways of smelting MZ-2 steel that are more cost effective than the duplex process.
  3. Confirm the chemical composition of nickel and carbon, especially to determine the feasibility of producing the armour without additional nickel.
  4. Explore the effect of chrome, silicon, and molybdenum on the characteristics of steel.
  5. Explore the optimal production process for MZ-2 steel.
The commission decrees that:
  1. Conditional on satisfactory results against 76 mm shells, the Chief of the Red Army ABTU and the Chief of the 7th Directorate of the People's Commissariat of Shipbuilding should accept MZ-2 into production for 40, 45, and 50 mm plates for A-34 tanks.
  2. MZ-2 steel is recommended for use in the production of 25 mm thick armour plates.
  3. The Ilyich laboratory should continue work on 30 and 35 mm thick plates, which demonstrated poor ductility during trials.
  4. Task the Ilyich laboratory with exploring the use of MZ-2 steel in the production of 55-75 mm thick plates. The 7th Directorate must provide the laboratory with a shooting range for a 76 mm gun for this work.
  5. Accelerate the completion of work to determine the suitability of MZ-2 steel for production of plates thinner than 25 mm.
  6. Establish the following tactical characteristics of MZ-2 armour:
  7. Thickness
    45 mm sample 0130
    45 mm 2-01991
    37 mm blueprint 3882
    12.7 mm DK
    0 degrees
    30 degrees
    0 degrees
    30 degrees
    0 degrees
    30 degrees
    0 degrees
    PTP
    PSP
    PTP
    PSP
    PTP
    PSP
    PTP
    PSP
    PTP
    PSP
    PTP
    PSP
    PTP
    PSP
    50
    745
    Higher than max velocity
    680
    712
    691
    >740
    743
    760
    -
    -
    -
    -
    45
    725
    755
    Higher than max
    680
    -
    663
    >685
    680
    710
    740
    760
    -
    -
    40
    669
    690
    740
    765
    665
    690
    -
    750
    630
    685
    675
    725
    -
    -
    25
    450
    530
    500
    560
    -
    -
    -
    -
    550
    650
    500
    650
    730
    -
  8. Advise the A-34 manufacturer to increase the thickness of the rear armour from 35 to 40 mm. At a cost of a small increase to mass (100 kg), it will drastically increase the performance of the vehicle.
  9. Accept the attached technical requirements draft. Propose and task the Ilyich laboratory with development of an MZ-2 plate fracture scale.
  10. Accept the attached instructions for production of MZ-2 steel by the Ilyich laboratory. Instruct the laboratory to develop a process to smelt steel using 50% of HNM steel byproducts."

19 comments:

  1. This goes some way to expose the misconceptions in the mettallurgic skill prevailing at the time about the effects of hardness on penetration on the soviet side and the lack of knowledge paying attention to fundamental differences in the correlation between hardness and resistence due to different armor penetration mechanics. High hardness MZ-2Z (IS-8S)relies entirely on it´s ability to completely break up the pentrator and is consequently very prone to failure by adiabatic shear when it does not succeed to break up the shell. Projectile failure was common with the inferior domestic 45mm APHE and APBC-HE projectiles -those against IS-8S armor specifications were laid out for to resist- and might even reasonably be justified against early ww2 german, uncapped 37mm and 50mm projectiles but once 50mm and 75mm capped Pzgr39 appeared, this armor resists with a significantly lower strength than 1930´s construction steel under conditions where the projectile cannot be shattered.

    I quote soviet trials conducted with captured 50mm PAK38 using Pzgr39 in spring 1942, courtesey M. Krogfuss:

    5.0cm Pzgr39 (PAK38) vs 45mm glacis plates (IS-8S) for T34.
    0°:363m/S (PTP) & 415m/s (PSP)
    30°: 411m/s (PTP) & 539m/s (PSP)

    To normalize their data, the soviets used the De Marre formula developed by Jakob de Marre in the 1880´s for penetration of homogenious nickel steel.

    The 0° figure equals a De Marre K =1750 for PSP of the Pzgr39. The soviet De Marre K for the 45mm [drawing 0130] AP at 0° and PSP is as high as K=2865 -this MZ-2Z armor looses almost 40% of it´s relative ballistic resistence strength due to absence of projectile shatter.

    For what´s worth, the soviets were well advised to employ highly sloped armor plate due to the breathtaking inferiority of that material at low obliquities against intact penetrators.

    ReplyDelete
    Replies
    1. As always, the great critical mass knows more about the trials than the people conducting them.

      Delete
    2. Also, the penetration figures for 50 mm capped AP that I posted before are 790-815 m/s, with the conclusion of "The upper front plate of the hull cannot be penetrated by 50 mm and 37 mm shells, barring cases where the tank is tilted forward due to terrain." But sure, breathtaking inferiority, etc. I'm sure it was this breathtaking inferiority that caused the Germans to abandon 50 mm guns.

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    3. "As always, the great critical mass knows more about the trials than the people conducting them."

      To be fair a lot has been discovered since January 25, 1940.

      But, you are right the 50mm Pzgr. 39 does not reliably penetrate the upper front hull of the T-34 at even 50 meters.

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    4. As always, the great Peter Samsonov knows more about the armor qualities and is impervious to any facts laid down in multiple penetration trials with capped shells.

      Bottomline - the Soviets tested their own high hardness plates and found them effective against their own AP projectiles designs which lacked AP caps. Of course they did, since everyone else figured that out already decades ago on large warships, and everyone else figured out that to prevent high hardness armor being very effective in reducing penetration by destroying the head of the AP projectiles was simply to add a sacrificable AP cap to the projectile. Once fitting AP caps became commonplace (i.e. everyone but Soviets, and the Germans were 'early adoptors') the tables turned and high hardness armor became a liability.

      Delete
    5. I posted "multiple penetration trials with capped shells", and the conclusions regarding those trials by contemporary Soviet scientists. This isn't my opinion, it's theirs, and their opinion is consistent between multiple trials. See, for instance:

      http://tankarchives.blogspot.ca/2014/05/german-steel-vs-soviet-steel.html

      http://tankarchives.blogspot.ca/2014/02/pziii-armour.html

      As for your "hurr durr, dumb Russians can't figure out caps", that is nonsense. Soviets explored performance of various types of AP and went with the one that worked best against armour, including foreign armour: https://tankarchives.blogspot.ca/2013/11/shell-shape.html

      Trials of foreign-obtained weapons and armour were frequently performed.

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    6. "Study of captured armour piercing shells and their comparative trials showed that:

      All captured shells without ballistic caps are sharp tipped. If there is a ballistic cap, the tip is dulled.
      The front part of the shell is very hard (up to 62-65 Rc), which is achieved by:
      use of instrumental steels
      welded on tip
      very fine grinding, and even polishing, of the shell tip

      Domestic armour piercing shells are made from more ductile 35 HGS grade steel, and, according to work of NII-24, are not improved by the above methods.
      Sharp tipped armour piercing shells are only superior when manufactured from instrumental steel. At this time, the transition to instrumental steel, requiring special thermal treatment for the required high hardness and polishing of the shell tip or a welded on shell tip, would be difficult, and production of large amounts of these shells is not possible."

      Which is, as You might notice, the exact opposite of what Peter Samsonov claimed.
      The soviets went on with the inferior, uncapped shell because they were not ready to invest in more careful heat treatment and better alloys, and because they failed to understand the importance of AP-caps and nose hardness until the 1950´s (when APCBC-HE finally replaced their various wartime designs, too).

      The careful observer might notice even that Pzgr39 series projectiles obtained higher Rc hardness, and better resistence to break up despite using a (not too chemically different) significantly leaner alloy composiiton than soviet shell steel by allowing more carbon to the shell steel and exercising tighter quality controll in regard to heat treatment.

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    7. It is interesting that Peter Samsonov is now filtering off replies.

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    8. Another conspiracy theorist? We've been over this. I enabled the spam filter months ago to stem the torrent of spam.

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    9. @critical mass: again, you claim things about Soviet research despite having no idea what it means. You say "All captured shells without ballistic caps are sharp tipped." Let's ask the Armoured Journal (Бронетанковый Вестник), Effect of Hardness of Steel Armour on Its Anti-Shell Resistance (ВЛИЯНИЕ ТВЕРДОСТИ СТАЛЬНОЙ БРОНИ НА ЕЕ ПРОТИВОСНАРЯДНУЮ СТОЙКОСТЬ), which discusses at great length the properties of 75 mm and 88 mm sharp tipped shells with caps and muzzle velocities of 1000 m/s. This is the only kind of ammunition for the 7.5 cm KwK 42 and 8.8 cm KwK 43 mentioned in the article. But, as always, you know more than any research scientist, right?

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    10. By the way, you still have not explained the terrible performance of "superior" German armour against "inferior" 45 mm shells compared to Soviet armour.

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    11. Actually, I explained that. You will find my memo in the three replys of mine which You have filtered out.

      And for the matter, I didn´t state "All captured shells without ballistic caps are sharp tipped", I quoted
      a line from Your soviet source, comrade...

      And for the record, I have assembled knowledge of the properties of german Pzgr39 projectiles far exceeding anything You believe to know about it. Your understanding ranges between sketchy at best, and outright misleading at worst. You fail to comprehend even the most basic principles of failure modes of both, armor plate and projectile and their correlation to hardness, even after I pointed out these errors. I will also not forget that You mislabelled the NII48´s T34 vulnerability graph when You posted it in Your blog with "50mm APCR on top, 37mm bottom", while the graph shows not only 50mm APCR but also (the furthest out #1 and #2 lines) 50mm APC (Pzgr39) vulnerabilities (out to 1.93km and 2.3km, respectively), information of which You decided not to mention.

      Soviet AP were terribly inefficient penetrators. De Marre K=2550-2450 for mid war projectiles, much worse than british US, or german AP. They improved only little by increasing the hardness from RC45 to Rc55 (post war) as testified by the lowering down to K=2200 for some lots of specially treated projectiles. Special heat treatment and /or higher grade shell steel was considered uneconomical for the Russians (they used highly alloyed steel for 122mm AP, though). You claimed -in blind ignorance of all facts- that they choosed the best projectile for work against their and foreign armor. It´s possible that they truly believed in this. If so, it only prooves a surprising lack of knowledge on the soviet part in armor and projectile metallurgy. Arguably, they would have won the war earlier with decent AP quality instead (such as Pzgr39 or /-D model APCBC-HE introduced in the 1950´s).

      Delete
    12. Right, so as always when there's a document that disagrees with you, you decide that it's wrong and keep blindly plowing forward while declaring that you're the smartest and actual scientists with access to relevant materials know nothing. When pressed, you fall back to flowery language like "terribly inefficient penetrators" (even though you were initially whining about the quality of Soviet armour against German shells, I don't know why you moved into Soviet shells now). Somehow in all the trials I've posted, this mythical superiority of German shells over Soviet armour never arises. You post a lot of assertions, but your massive walls of text are heavy on insults and very low on evidence. It's very convenient that you have an excuse for that too.

      Delete
  2. Maybe You should read my memo more carefully.

    "For what´s worth, the soviets were well advised to employ highly sloped armor plate due to the breathtaking inferiority of that material at low obliquities against intact penetrators."


    Because You refer to only two, extremely oblique datapoints (65° and 55° impact, respectively for capped 50mm AP), not 0° or 30°, which matter here, or even medium obliquity realm. At such extreme oblique impact, the Pzgr39 cannot be expected to stay intact. Thus, the penetration mechanics change back towards plugging and projectile break up, which deletes any advantages intact penetrators may have.

    You should know that there is a difference in projectile behavior between 0° or 30° on the one hand and >45° on the other.
    Soviet MZ-2Z armor plate was service acceptance tested at 0° impact with 45mm AP, not at 55°, making the latter reference pretty much a red herring to this discussion.






    ReplyDelete
    Replies
    1. Mhm, so that's why 5 cm Pzgr 39 behaviour in Soviet trials against the vertical 45 mm side of the T-34 behaved pretty much exactly (a little worse, even) as predicted by calculations with K=2400 armour, right?

      Also please explain how German armour performed much more poorly in Soviet trials than Soviet armour against this inferior 45 mm ammunition.

      Delete
  3. ...would it be rude to point out it was the Germans who went on to greatly (and arguably excessively) increase the frontal armour thickness of their workhorse AFVs to deal with the "inferior" Soviet shells, rather than the other way around?

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  4. Soviet vulnerability figures for T34 are more negative than german Panzerbeschußtafel, because the latter assume a higher resistence quality, more in line with actual armor grade steel.

    NII48 tested captured 50mm PAK38 firing Pzgr Gg (AP-HE) and Pzgr39 (APC-HE) vs domestic 45mm armor plate in spring 1942.
    Their 45mm armor plate was found vulnerable to 5cm Pzgr39 out to ranges approaching (and exceeding) 2km due to the poor resistence vs intact projectiles. At a range of 2.3km, the terminal velocity dropped down to 358m/s for the PAK38. The De Marre K for PTP against the Pzgr39 was as low as K=1510 (worse than mild steel), for PSP K=1750 (roughly on par with high strength construction steel).
    Any claim by Peter Samsonov claiming a K=2400 for vertical 45mm plate vs 5cm Pzgr39 are in error as demonstrated by CAMD RF 38-11355-776.

    https://ibb.co/mqc59b

    45mm soviet HHA domestic armor plate vs:

    1-50mm Pzgr39 (V0:835m/s) PTP =2300 m @0° (!)
    2-50mm Pzgr39 (V0:835m/s) PSP =1930 m @0° (!)
    3-50mm Pzgr40 (V0:1200m/s) PTP =1400 m @0°
    4-50mm Pzgr40 (V0:1200m/s) PSP =1300 m @0°
    5 & 6 are 45mm domestic AP a PTP =200m @0°
    (notice this 45mm AP performance is WORSE due to shatter than german 37mmm AP, which obtains a PTP = 700m @0°.

    ReplyDelete
    Replies
    1. What is this, a table for ants? Meanwhile, here's a trial you can actually read: http://tankarchives.blogspot.ca/2015/07/comparative-testing.html

      "the 50 mm shell can penetrate the side from normal at a range of 900-1000 meters, and the 37 mm shell at 150 meters."

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    2. Here's the PTP for the 45 mm gun: 350 meters http://tankarchives.blogspot.ca/2013/06/soviet-45-mm-at-guns.html

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