Wednesday, 14 August 2013

German Armour Quality

During WWII, the relations between Britain and the USSR have been quite close. Aside from material aid (the British sent Lend-Lease tanks and equipment, the Soviets sent captured German tanks and their own samples), the two countries exchanged intelligence. Here is one of many such exchanges, from CAMD RF 38-11355-2704:

"Tendencies in the manufacturing of German armour plates (excerpts from the report prepared by the Head of the Main British Tank Development Directorate)

The testing of a Tiger tank recently brought to England showed a deviation from typical German armour protection techniques. None of the armour was surface hardened. The hardness on the Brinell scale is as follows:
  • Thin horizontal plates (26 mm thick): 298-343
  • Thick nearly vertical plates: 257-310
The fact that the armour is no longer surface hardened, and has a relatively low Brinell hardness, is very important. It must be noted that this change coincides with the appearance of new German heavily armoured tanks: Tiger, Panther, Ferdinand. Until now, no German tank had armour thicker than 50 mm.

The deviation from existing practices is explained by the following reasons, or their combination.
  1. Economic reasons. It is very possible that the very amount of armour overloaded the German capacity to manufacture it, and Germany was forced to utilize heavier manufacturing, usually tasked with manufacturing simple armoured plates. There might be a shortage of equipment capable of processing thick armoured plates.
  2. Mechanical finish problems. The three aforementioned vehicles have interlocking armoured plates to increase the strength of the welds. Regular step connections were preserved. The combination of these two connections reduced the ability to produce a large number of armoured hulls. Perhaps the softer plates were introduced to remedy these problems.
  3. Ballistic factors. The three aforementioned vehicles were built for the purpose of long ranged combat. It is possible that the enemy introduced softer armoured vehicles knowing that the Allies use armour piercing capped shells. Use of these shells against soft armour is suboptimal. If soft armour continues to be used, we must explore the question of ballistic caps. However, it is necessary to collect more information, as this armour could still be surface hardened. 
It is necessary to examine a Panther tank and perform experiments on armour of Tiger tanks built later than the one mentioned in this report."

The report came out in January of 1944, so not many Tigers were built after that. The Americans, meanwhile, tested the armour of the Panther. Their findings spoke rather poorly of German manufacturing. Their findings were the same as what any of my readers have already seen: German armour is of poor toughness, and their welding seams have a tendency to burst under pressure.


  1. 1) Its not that easy.
    Homogenous armor is not in any case worse than face-hardened armor, that should be noted here.

    Successfull German use of face hardened armor during the early stages of the war was because allied fielded a lot solid AP shells. AP shells without a cap may shatter against the high hardness layer on the surface of the face hardened armor.
    However allied intelligence fitted their rounds with caps as well and now the FHA was very well penetrateable for them.

    As example, Shermans 75mm APCBC round against Panzer IVH front (85mm@10°):
    - if the front was face hardened, the Sherman's APCBC could penetrate it at up to 940m
    - if the front was homogenous, the Sherman could penetrate it only at up to 150m (!)

    Homogenous armor was infact more resistant against capped rounds. Thus i bet on your first point, the economical reasons, because the expensive electrical induction face hardening was not needed anymore with the rise of capped shells.

    [1] WW2 Ballistics: Armor and Gunnery

    2) The Panther plate in the report was one of the late ones. Mb (because it was in short supply) has been replaced by V (vanadium) already, thus shattering.

  2. US engineers were not kind to the Russian armor either.

    Watertown Arsenal for metallurgical examination:

    The very high hardness encountered in most Soviet tank armor has
    caused much unnecessary concern regarding the relative ballistic performance of the hard Soviet armor and the softer American armor. Many people associate high hardness with high resistance to penetration. Although this is true, within limits, in the case of attack of armor by undermatching projectiles (i.e. caliber of shot is less than the thickness of the armor), articularly at low obliquities of attack, it is definitely not true when the armor is attacked by larger caliber
    shot at higher obliquities of impact. Competitive ballistic trials which have been conducted at ordnance proving grounds on both very hard and normally hard domestic armor and Soviet armor have established beyond question of doubt that in many cases, representative of actual battlefield attack conditions, very hard armor is distinctly inferior in resistance to penetration as compared to armor of more conventional hardnesses (280-320 Brinell).

    1. That doesn't necessarily means the armor is bad, read the full report... It's a mostly deflective armor, not a resistive one, it's designed to deflect overmatching projectiles, not resisting direct impact/penetration.
      The key is that soviet engineers tried to avoid penetration at all, to reduce damage from HE AT and prolonged low-caliber fire, that lead to the adoption of harder armor.

  3. I made an article about this some time ago (in spanish):

    Germans didn't say their armor quality was bad or worse, but the enemies (british, soviets and americans) say their qualitie fell down. Armor more brite and less hardened.

    FH was used to break enemy AP shells when impacting their armor. Once the shell penetrates, FH armor is a little less resistance than normal armor.

    SS, I can send you the book "WW2 Ballistics: Armor and Gunnery" if you don't have it yet (pdf).


  4. True is, that due to ressource shortness, V was replaced by Mb as steel component, leading to more brittle plates. Also, the inductive face-hardening took too much time, and was too expensive. Early PzIV plates were hardened to the state of a good kitchen knife.
    So, Imho, it was both factors: Capped shells calling for softer armour, and economic reasons calling for cheaper production. German tanks were generally too expensive for wartime conditions. Later models would be delivered bright red with only anti-corrosion coating, and a box of paint powder that could be mixed with fuel for the crew to paint the tank themselves, now what does that tell you?
    Biggest Problem AFAIK was the brittleness of inferior Mb-steel qualities due to the shortage of high quality steel components (also for the gearbox and transmissions of tigers and panthers, that called for very high steel qualities!)

    1. I think I confused Mb and V , and their respective effects, but in the end, the shortage demnded chage of material.
      The american report on the Panther armor also explicitly states that inadequate production conditions eliminated any potential the new material composition could have been providing. Especially the hardening was done inexpertedly, speaking of great haste in the process. So, no, german armour was not that great, and later in the war, not so good at all. Plus, It showed the basic problem of german engineering: Very sophisticated design ideas, that called for overly complicated, horribly expensive manufacture, using top-quality material, which in reality quickly led to crappy products due to sloppy production and shabby material available

    2. Tests of early model panthers by the allies in Normandy showed some faulty plates in one or two tanks, but general armour quality was reasonable in war conditions.

  5. "However, it is necessary to collect more information, as this armour could still be surface hardened." (#3)

    What exactly is this supposed to mean? Is this as in, "other Tigers could still be carrying face hardened armour"?

    1. The term reappearing in primary sources for secondary application of face hardening to homogenious armour is "Einsatzgehärtet"

      You would heat up the surface of the plate by a heat source for a certain period and spray it with water immediately after.

      A crude procedure, not very effective. The surface gets hardened a bit but the back stays soft.
      The hardneing is sufficient to break up pointed, uncapped shells, which may result in shatter, depending on the cal/plate ratio, obliquity and velocity.

      The tough, ductile back is smaller than with full homogenious armour, so if the face doesn´t succeed in breaking up the shell (like f.e. with well treated, capped AP, where the cap protects the nose tip), it will reduce the effectivity of armour to resist the shell in penetration

  6. The hardness of homogenious armour is inversely correlated to ductility and section thickness. While You may have thick plates at high hardness, they would tend to be brittle and thus, less resistent to perforation.

    Thinner plates can have superior hardness at acceptable ductility because it was easier to controll the heat removement in thinner sections and thus keep the desired fibrous structure.

    At high obliquity impact, soft plates are definetely superior to hard plates because

    a) they tend to damage the penetrator less, a nose damaged projectile against a harder plate would inhibite ricochet, the projectile would undergo more often than not the attempt to penetrate rather than deflect

    b)harder plates normalize at significantly higher degrees than softer armour plates, thus reducing the benefit of high obliquity

    c) the effect of tensile strength / hardness is more pronounced in measurement of plate resistence at low obliquity and drops with increasing obliquity. Depending on the cal/plate relationship, there will be a cross over point at which point a harder plate is inferior to a softer plate

    "face hardened" tank armour is basically "harveyized" surface-only hardened homogenious armour. It´s not what the Navy understands under the term "Face hardened" (=decrementally hardened KC derivative).

    Navy KC armour would be superior to capped and uncapped shell but the only case, I am aware of where Navy armour was intended to be used (doubtful if ever executed) was for the MAUS.