Military Review

German shells against Soviet armor: tested in the Urals

37

Anti-tank gun 7,5 cm Pak 40. Source: pinteres.se


Saw and smite


In the previous part stories the narrative stopped at sub-caliber shells, or "coils". But in the arsenal of anti-tank artillery there were other types of ammunition. Among the trophies were individual 75-105-mm HEAT shells, the principle of which is described in the report as follows:

"By means of a spherical-goblet-shaped notch in the explosive made in the head part, the blast wave is directed and, concentrating on a small area, acquires the ability to penetrate armor."

There is not a word in the text about the material lining the recess, and the whole description is based on the concentration of the shock wave that breaks through the armor barrier. The explosives of such shells consisted of 45% TNT and 55% RDX mixed with paraffin. Among the advantages, researchers of German shells note the lack of dependence of the ammunition's lethality on speed. In general, the Germans in the leadership write that to shoot at tanks cumulative projectiles can be from a distance of up to 2000 meters. It was not possible to verify such a statement in Sverdlovsk, since the lack of trophy shells forced them to hit targets for sure and from minimum distances. The cumulative ones were generally not enough for a full test on Soviet armor.

German shells against Soviet armor: tested in the Urals
Source: 1942 Report

As already mentioned in the first part of the material, two types of armor were prepared for testing at the test site of plant No. 9 and ANIOP (Artillery Research Experimental Test Site) in Gorokhovets. High-hardness alloys were represented by grade 8C, which became the main armor for T-34 tanks, and medium-hard alloys were FD-6633 steel for the KV series. By the way, the industry name of the armor for the T-34 is silicon-manganese-chromium-nickel-molybdenum steel, grade 8C. In Sverdlovsk, three 8C armor plates with a thickness of 35 mm, 45 mm and 60 mm and dimensions of 800x800 mm and 1200x1200 mm were subjected to shelling. In the same series, two huge plates of 3200x1200 mm in size from armor of medium hardness with a thickness of 60 mm and 75 mm were fired upon. At the Gorokhovets test site, two plates of medium hardness of 30 mm and 75 mm with a size of 1200x1200 mm and a 45-mm plate of the same size made of 8C steel were tested by shelling.

A small excursion into the armor theory. Homogeneous armor of high hardness due to relatively low plasticity was used only to protect against bullets and shells of small-caliber artillery (projectile caliber 20–55 mm). With the high quality of the metal, providing increased viscosity, homogeneous armor could also be used to protect against 76 mm projectiles. It was the last property that was successfully implemented by domestic gunsmiths on medium tanks. In Germany and its allies, high hardness armor was also used to protect all tanks adopted at that time (T-II, T-III, T-IV, etc.). All gun and machine-gun shields with a thickness of 2-10 mm, helmets and individual protection shields with a thickness of 1,0 to 2,0 mm were also made of high hardness armor. In addition, high-hardness armor has found wide application in aircraft construction, in particular, it was used to arm aircraft hulls. Homogeneous armor of medium hardness, which has a higher ductility in comparison with armor of high hardness, could be used to protect against larger shells of ground artillery - caliber 107-152 mm (with an appropriate thickness of armor protection) without unacceptable fragile metal damage. It is noteworthy that the use of armor of medium hardness to protect against bullets and shells of small-caliber artillery turned out to be impractical due to a decrease in penetration resistance at a reduced hardness. This was the reason for the choice of the 8C high-hardness armor as the basis for the T-34. The most effective use of homogeneous armor of medium hardness was recognized for protection against projectiles of caliber from 76 to 152 mm.

The chemical composition of steel 8C: 0,21–0,27% C; 1,1-1,5% Mn; 1,2-1,6% Si; ≤0,03% S; ≤0,03% P; 0,7-1,0% Cr; 1,0-1,5% Ni; 0,15-0,25% Mo. 8C steel armor had a number of significant drawbacks, mainly depending on the complexity of its chemical composition. These disadvantages included a significant development of fracture layering, an increased tendency to form cracks during welding and straightening of parts, as well as the instability of the results of field tests and a tendency to brittle damage in case of inaccurate adherence to the armor manufacturing technology.


Source: t34inform.ru

In many respects, the difficulties in achieving the required characteristics in the 8C grade armor metal lie in the increased silicon content, which led to an increase in fragility. The technology for the production of 8C armor, while maintaining all the requirements, was inaccessible in peacetime, not to mention the war period of total evacuation of enterprises.

Homogeneous armor of medium hardness, to which the FD-6633 belongs, was developed in the USSR at the end of the 30s in the armored laboratory No. 1 of the Izhora plant, which later formed the basis of the TsNII-1939, created in 48. Having no experience in the development of armor of this class, the Izhorian metallurgists fully mastered production in 2 months. It must be said that making armor for heavy tanks was easier than for medium T-34s. Minor deviations from the technological cycle did not cause such a serious drop in quality as in the case of 8C. After all, medium hard armor made any machining after hardening much easier. An exceptional advantage of medium-hard homogeneous armor was also low sensitivity to welding cracks. The formation of cracks during welding of shells made of armor of this type was a rare case, while when welding shells made of 8C armor, cracks were formed at the slightest deviations in technology. This was encountered quite often on the T-34, especially in the early years of the war.

A little about the chemical composition of medium hard armor. First of all, such steel requires molybdenum, the proportion of which should not be less than 0,2%. This alloying addition reduced the brittleness of the steel and increased the toughness. The Sverdlovsk report of 1942 provides the following data on the chemical composition of medium-hard armor FD-6633: 0,28-0,34% C, 0,19-0,50% Si, 0,15-0,50% Mn, 1,48, 1,90-1,00% Cr, 1,50-0,20% Ni and 0,30-75% Mo. Such a large range of values ​​is explained by the different thicknesses of the armor images: the composition of steel 30 mm thick could differ significantly from the XNUMX mm armor.

Against German shells


The resistance to shells of domestic high-hardness armor was higher than that of average hardness. This was shown by the pre-war tests. For example, for full protection against blunt-headed 45 mm projectiles, medium-hard armor 53–56 mm thick was used, while in the case of high-hardness armor, the minimum thickness that provides protection against these projectiles is 35 mm. All this together gives considerable savings in the weight of the armored vehicle. The advantages of 8C armor are further enhanced when tested with sharp-headed projectiles. To protect against such projectiles with a caliber of 76 mm, the minimum thickness of rolled armor of medium hardness was 90 mm, for protection against a sharp-headed projectile with a caliber of 85 mm, the minimum thickness of rolled armor of high hardness was 45 mm. More than double the difference! Despite this overwhelming advantage of 8C steel, medium-hard armor is rehabilitated in tests at high angles when toughness comes to the fore. In this case, it allows you to more successfully withstand the powerful dynamic impact of the attacking ammunition.


Source: ww2.games.1c.ru

In 1942, domestic testers did not have a wide variety of captured ammunition, so the firing range was limited to 50 and 150 meters with a standard charge of gunpowder. In fact, there were at best 2 shots for each sample, which slightly spoiled the reliability of the results. The important parameters for the testers were the PTP angle (the ultimate back armor strength) and the PSP angle (through the armor penetration limit). The angles of meeting the armor with the projectile were 0, 30 and 45 degrees. A feature of the tests at the test site in Gorokhovets was the use of reduced charges of gunpowder, which made it possible, at a constant distance of 65 meters, to simulate various projectile speeds. The reloading of German ammunition was carried out as follows: the muzzle was cut off from the sleeve and the projectile was inserted into the muzzle of the gun, and the charge was placed separately behind it. For comparative tests with captured armor-piercing and sub-caliber ones, 76-mm domestic cumulative projectiles were fired at a 30-mm plate made of high-hardness armor and 45-mm medium-hard armor.

The intermediate results of testing captured artillery shells were the expected better durability of 8C high-hardness steel in comparison with medium-hard armor FD-6833. So, the angles of the rear strength limit, which guarantee the protection of the crew and units, for 60 mm armor of medium hardness are 10-15 degrees more than for the same thickness of high hardness. This is true for German APCR shells. That is, all other things being equal, the plates of the FD-6833 armor had to be tilted at a greater angle to the attacking projectile than the 8C armor. In the case of using a 50-mm sub-caliber projectile, medium-hard armor to maintain the rear strength required tilting 5-10 degrees more than the 8C plates.

At first glance, a bit of a paradox, considering that 8C was intended for medium tanks, and medium-hard armor was for heavy ones. But it was this factor that determined the high projectile resistance of the T-34, of course, subject to the observance of all the technological subtleties of the manufacture of armor and the tank hull.

But with German armor-piercing shells for 8C armor, the situation was not so rosy: the PTP and PSP angles for a 60-mm high hardness plate were already 5-10 degrees more than for medium hard armor. When the turn came to cumulative domestic 76-mm shells, it turned out that they were not able to hit armor up to 45 mm thick. The given charge simulated a shot distance at a target of 1,6 km. Captured cumulative projectiles, due to insufficient supply, were not included in the study.

To be continued ...
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German armor-piercing: Sverdlovsk studies of 1942
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  1. polpot
    polpot 16 September 2020 18: 09
    +9
    Thank you, an interesting topic, we look forward to continuing.
  2. The leader of the Redskins
    The leader of the Redskins 16 September 2020 18: 32
    +7
    A very interesting continuation. I read the first part with pleasure. We are waiting, we are waiting.
  3. mark1
    mark1 16 September 2020 19: 01
    +1
    The surface layer of the armor was hardened by HFC or by some other method (cementation before the war), so it was not homogeneous (unchanged in properties and composition to the entire depth), but heterogeneous
    1. Free wind
      Free wind 17 September 2020 04: 33
      +2
      Steel with a carbon content of up to 0,3% does not heat up, well, it is not capable of this, in the books it is written so, for T-34 carbon up to 0,27% ..
      1. mark1
        mark1 17 September 2020 05: 45
        0
        Read the process for the production of an armored hull and a tower - there is a vacation and subsequent hardening, the cast towers were hardened all the more.
        1. Vladimir Demyanov
          Vladimir Demyanov 17 September 2020 13: 40
          0
          First quenching, and then - tempering, to reduce the resulting stresses and equalize the mechanical properties. It is a special steel, as indicated by the letter "c". Otherwise, according to the adopted standard 8, this is the carbon content, in structural steels in hundredths of a percent, in instrumental steels in tenths. Here, as you can see, the carbon content is not more than 0,3 and there are alloying elements, by the way, increasing the hardenability of steel.
      2. Vladimir Demyanov
        Vladimir Demyanov 17 September 2020 13: 22
        0
        If there are no alloying elements, then St3 should not be hardened. According to the chemical composition given in the article, steel 8c (the designation does not correspond to the accepted standard), there are elements that increase both the hardness and hardenability of the specified steel.
        1. Free wind
          Free wind 17 September 2020 13: 27
          0
          is hardened precisely due to the carbon content. most likely in numbers something is confused. According to what I see it is soft steel, and it does not heat up.
          1. Vladimir Demyanov
            Vladimir Demyanov 17 September 2020 22: 28
            0
            Free wind, in this steel manganese up to 1,5%, chromium up to 1%, and they just increase the hardness during heat treatment; nickel increases ductility, molybdenum gives shock resistance. Silicon, with such a content (1,2 -1,6%), increases the hardness, but worsens the weldability due to the high fluidity and the formation of refractory silicon oxides. Sulfur and phosphorus content ... Acceptable for open-hearth steel. At that time, electroslag remelting was still unknown, as were the subsequent methods for reducing the S u F content.
  4. Alf
    Alf 16 September 2020 20: 09
    +6
    Fine ! This article is now very rare in terms of information content.good hi
    1. Alf
      Alf 16 September 2020 21: 30
      +6
      Quote: Alf
      Fine ! This article is now very rare in terms of information content.good hi

      Hey, alternatively gifted miner! Twice two equals four. Disagree.
  5. Captain Pushkin
    Captain Pushkin 16 September 2020 20: 28
    0
    Quote: mark1
    The surface layer of the armor was hardened by HFC or by some other method (cementation before the war), so it was not homogeneous (unchanged in properties and composition to the entire depth), but heterogeneous

    Before the war, the Germans actually cemented the surface layer.
    But I haven’t heard about the armor of the T-34 and KV. She was homogeneous.
    1. Free wind
      Free wind 17 September 2020 04: 44
      +1
      The surface layer of the finished product is cemented, that is, the surface is carbonized. One of the ways is to place a red-hot part, an ancient method, place a red-hot part in coal dust. I somehow used sinetalk, I do not know what this powder is scientifically called. He heated the spline part of the shaft and sprinkled it with this powder. The Germans covered the surface of the tanks with an anti-magnetic layer, zimerite. Maybe you are confusing this.
      1. Captain Pushkin
        Captain Pushkin 17 September 2020 19: 42
        0
        Quote: Free Wind
        The Germans covered the surface of the tanks with an anti-magnetic layer, zimerite. Maybe you are confusing this.

        Ask for a description of the German T-III and T-IV, their armor was cemented.
        The fact that the armor of the T-34 and KV was homogeneous is confirmed by Alexey RA in the commentary of my post.
      2. Vladimir Demyanov
        Vladimir Demyanov 17 September 2020 22: 42
        0
        Free wind, an even more ancient method, processing in crucibles with horns and hooves. So even under Alexander Nevsky and earlier, raw iron was saturated with carbon and swords were forged. And for artillery this method was used, described in the Charter of the pre-Petrine time.
    2. Alexey RA
      Alexey RA 17 September 2020 09: 21
      +2
      Quote: Captain Pushkin
      Before the war, the Germans actually cemented the surface layer.
      But I haven’t heard about the armor of the T-34 and KV. She was homogeneous.

      Cemented armor in the USSR was on pre-war tanks - the same T-26 and T-28. They wanted to make a T-50 armored hull out of it.
      But during the SPV, when knocked out armored vehicles came massively from the front, and the factories started shielding tanks, the BTV faced the fact that cemented armor does not like cutting, welding and other hot work very much - after them the surface-hardened layer in the work area disappears. Moreover, the problems when working with such armor were not only in the units, but also in the factories. It got to the point that LKZ simply refused to take T-28 with cemented armor for shielding. Therefore, cementation was abandoned for the sake of the maintainability of the tanks.
  6. lucul
    lucul 16 September 2020 22: 10
    -1
    A small excursion into the armor theory. Homogeneous armor of high hardness due to its relatively low plasticity was used only to protect against bullets and shells of small-caliber artillery (projectile caliber 20–55 mm). With the high quality of the metal, providing increased viscosity, homogeneous armor could also be used to protect against 76 mm projectiles. It was the last property that was successfully implemented by domestic gunsmiths on medium tanks.

    That is, in fact, 8C high hardness armor successfully held all shells from 30mm to 75mm inclusive (it was designed against them). And against 85-120 mm shells, it did not make sense to increase the thickness of the armor, because a shell of this caliber, having high kinetic energy, simply split the armor, and did not make a neat hole.
    Now it is clear why ours did not increase the frontal armor on the T-34. Against shells, caliber 85-120 mm, different armor was required (of medium hardness), which would require a complete remake of the entire tank.
    Which was implemented on the T-44, a worthy opponent of the Panther, but did not go into production.
    And so the article is good ...
    1. mvg
      mvg 16 September 2020 23: 03
      -2
      8C high hardness armor successfully held all shells from 30mm to 75mm

      Come on. So the T-34s are simply invulnerable at the beginning of the war. However, they made their way from 37 mm inclusive. And on the forehead too. 75 mm is a sure penetration, if not a cigarette butt from an early T-4.
      Panther 75 mm pierced EVERYTHING that was. From any direction.
      1. lucul
        lucul 17 September 2020 05: 57
        +1
        So T-34s are simply invulnerable at the beginning of the war.

        Almost, only 88mm antiaircraft gun and 150mm howitzer left the T-34 no chance.
        However, they made their way from 37 mm inclusive

        When did subcalibers appear for all these guns, in what year? ))) It was thanks to the acquaintance with the T-34 armor that the Germans began to develop sub-calibers.
        75 mm is a sure penetration, if not a cigarette butt from an early T-4.

        What cigarette butt ???? Look at the 75mm cannon of 1940 tanks, that barrel length was the norm for that year.
        Panther 75 mm pierced EVERYTHING that was.

        A panther with a spear, more precisely. Otherwise, that gun (with a barrel length in calibers) cannot be named.

        However, they made their way from 37 mm inclusive

        According to an eyewitness, though this is not World War II:

        1. Alexey RA
          Alexey RA 17 September 2020 09: 24
          +1
          Quote: lucul
          Almost, only 88mm antiaircraft gun and 150mm howitzer left the T-34 no chance.

          Gorokhovets polygon. The results of tests of captured guns and ammunition for domestic armor (from October 9 to November 4, 1942):
          50-mm anti-tank gun PaK.38, ordinary armor-piercing:
          The 75-mm sheet normal showed the back strength limit of 700 m, the through penetration limit of 400 m. That is, starting from a distance of 700 m and closer PaK.38 can penetrate unshielded HF armor, with 400 m it is guaranteed to break through.
          The 45-mm sheet along the normal showed the through penetration limit of 1500 m, at an angle of 30 degrees to the normal 1300 m.
          That is, PaK.38 confidently hits the T-34 in the side and the tower at any real combat distance.

          50-mm anti-tank gun PaK.38, sub-caliber:
          The 75-mm sheet normal showed the back strength of 870 m, the through penetration of 740 m, at an angle of 30 degrees to the normal of 530 and 470 m, respectively.
          The 45-mm sheet along the normal showed the through penetration limit of 1300 m, at an angle of 30 degrees to the normal 700 m.

          37-mm anti-tank gun PaK.36, ordinary armor-piercing:
          The 45-mm sheet normal showed a rear strength limit of 700 meters - that is, starting from 700 meters the “mallet” can dig through the side and the T-34 turret.

          37-mm anti-tank gun PaK.36, sub-caliber:
          75-mm sheet along the normal showed the durability limit of 180 m, the limit of penetration through the 120 m.
          45-mm sheet along the normal showed the limit of the durability of 440 meters, the limit of penetration through the 350 meters, at an angle of 30 degrees from the normal 200 and 150 meters, respectively.
          © D. Shein
        2. Bormanxnumx
          Bormanxnumx 17 September 2020 11: 08
          +2
          Quote: lucul
          According to an eyewitness, though this is not World War II:

          The words of eyewitnesses should be treated with a reasonable degree of skepticism. A striking example is the reviews of American soldiers about the effectiveness of the RPG "Bazooka", which took the German Panther head-on without any problems, and during the war in Korea suddenly "dramatically exhausted itself" and became ineffective against the 45mm armor of the T-34-85 tank.
          1. Captain Pushkin
            Captain Pushkin 17 September 2020 21: 16
            +1
            Quote: BORMAN82
            Quote: lucul
            According to an eyewitness, though this is not World War II:

            The words of eyewitnesses should be treated with a reasonable degree of skepticism. A striking example is the reviews of American soldiers about the effectiveness of the RPG "Bazooka", which took the German Panther head-on without any problems, and during the war in Korea suddenly "dramatically exhausted itself" and became ineffective against the 45mm armor of the T-34-85 tank.

            This is especially true for American eyewitnesses.
            For example, one Saber pilot claimed that he personally knocked out 50 T-34s from 12,7mm machine guns during the Korean War.
            Believe it or not from the series.
        3. mvg
          mvg 17 September 2020 22: 44
          0
          Almost, only 88mm anti-aircraft gun and 150mm howitzer left the T-34 no chance

          Often the Germans had 88 mm anti-aircraft guns and 107 mm corps guns in the anti-aircraft gunnery? But the T-34 did not have much of a chance. How else to explain the failure of 41? Read real tests in Kubinka. Maybe Fedorov will stop verbiage for 3-4 volumes, and get down to business with tables and real shooting.
          What cigarette butt ???? You look at the 75mm cannon of 1940 tanks
          Here in the photo, Pak40 February 42, Pak38, an earlier 50 mm model, French 74 mm, arr 1897. What are these "butts"? In 50 mm Pak38, the probability of penetration into the forehead of the T-34, from 300-500 m is approximately 50%. At 75 mm Pak 40, at real combat distances, almost 80-90%.
          according to an eyewitness

          These are not "eyewitnesses", this is the director. I can't watch this, I spare my psyche.
    2. Niko
      Niko 17 September 2020 17: 06
      +1
      It looks like you didn't read the previous articles of the author carefully. About research on REAL damage t 34 yes and this article talked about problems with REAL armor quality
  7. Undecim
    Undecim 16 September 2020 22: 16
    +2
    There is not a word in the text about the material lining the recess, and the whole description is based on the concentration of the shock wave that penetrates the armor barrier. The explosives of such shells consisted of 45% TNT and 55% RDX, mixed with paraffin.
    The picture shows the German 7,5 cm Granatpatrone 38 HL cumulative projectile.

    Steel lining of the cumulative funnel. Explosive charge - 59% of cyclonite (RDX), phlegmatized with trinitrotoluene (39%) and wax (3%).
    Normal armor penetration - 100 mm. The firing range is 1500 m.
    1. Undecim
      Undecim 16 September 2020 22: 42
      +2
      Typo. 58% cyclonite.
  8. Aviator_
    Aviator_ 16 September 2020 22: 24
    +1
    When the turn came to cumulative domestic 76-mm shells, it turned out that they were not able to hit armor up to 45 mm thick.

    Maybe not "before", but from above? Otherwise, it turns out that thin armor holds the shell better than thick armor. And so the article is interesting, respect to the author.
  9. Free wind
    Free wind 17 September 2020 04: 28
    0
    that I did not understand anything in numbers. composition of steels, by numbers. Steel 8C, in terms of carbon, is a low-carbon steel, but the hardness was added by adding manganese and silicon, initially there were a lot of harmful impurities, like sulfur and phosphorus, the percentage was reduced, again due to silicon and manganese. Chromium and nickel add plasticity, there are other properties, for example corrosive, but they are not important, molybdenum in such quantities does not affect anything. I would say ordinary structural steel. KV armor should be harder. For German armor of high hardness, it seems to be considered plastic. There were many cases when the ZIS-2 penetrated German tanks right through without any harm, that is, there were either no fragments or there were few of them, the crew was not surprised. With cumulative factors, it’s quite a problem.
    1. Undecim
      Undecim 17 September 2020 07: 18
      0
      I didn't understand anything in numbers
      What exactly is not clear to you?
      1. Vladimir Demyanov
        Vladimir Demyanov 17 September 2020 13: 47
        0
        I tried to explain by numbers, maybe clumsily: I haven't worked with metal science for a long time.
        1. Undecim
          Undecim 17 September 2020 14: 14
          0
          I understand that you doubt the possibility of hardening steel with a carbon content of less than 0,25% to the required hardness?
          1. Vladimir Demyanov
            Vladimir Demyanov 17 September 2020 21: 48
            +1
            If steel besides carbon does not contain other elements that increase the hardness after heat treatment, then yes. The steel, which is held in the article, although it is low-carbon, contains elements that increase hardenability and increase the hardness after heat treatment (hardening + tempering, for tank armor made of this steel). Did I answer your question?
            1. Undecim
              Undecim 17 September 2020 22: 19
              +3
              Yes, I actually thought you were looking for an answer. But I see that you yourself own the issue in general terms.
              1. Vladimir Demyanov
                Vladimir Demyanov 18 September 2020 07: 17
                +1
                Thank. The composition of tank armor has always been a secret. Before the start of the war, the intelligence of future enemies always hunted him.
  10. Captain Pushkin
    Captain Pushkin 17 September 2020 21: 10
    0
    Quote: lucul
    Which was implemented on the T-44, a worthy opponent of the Panther, but did not go into production.

    The T-44 tank was produced from 1944 to 1947, the total number of vehicles was 1823 units.
    In World War II, he did not fight, like the IS-2
  11. serezhasoldatow
    serezhasoldatow 21 September 2020 20: 10
    0
    "to protect against bullets and shells small-caliber artillery "Author! There is no such artillery !!!" The article is very interesting, I look forward to continuing.
  12. Comrade Kim
    Comrade Kim 11 November 2020 08: 57
    0
    Quote: Leader of the Redskins
    A very interesting continuation. I read the first part with pleasure. We are waiting, we are waiting.

    We are waiting!