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T-34 – Mice VS Cats – Part 11

2015-11-21

In case if you missed it, here is the previous part

Let’s go back to Guderian words. The trouble with memoirs they are not written by actual Authors, but by professional writers and futher edited by editors in that way it will sell better. I can bet my balls but Guderian could not find Vanadium on periodic table. Besides what kind of difficulties with raw materials Krupp could possibly face in 1941?

To answer that question let’s have a look what Soviet engineers (Research institute – 48) spoke themselves about German armored steel in 1942 after testing captured German tanks.

The investigated armour steels of captured tanks are in the majority of the cases are more alloyed than armour steel of domestic manufacture. Due to that the chemical composition of the investigated stamps do not represent the interest for domestic armour production.

 

After finished with  chemical composition of armoured steel its time to talk about armoured steel composition – homogeneous armour vs layered or cemented armor.

Homogeneous armour steel – the structure and chemical composition is uniform throughout its thickness. Also Homogeneous armour steel may be rolled or casted. Rolled armor is superior to casted armour. As example T-34 turret from rolled steel was 45mm thick, while cast turret had to be 52mm thick.

Layered or cemented armor – name speaks for itself, armoured steel is layered. The easier example if hard layer is followed by soft layer and followed again by hard layer. It was kind of early years of composite armour. Another distinctive feature of layered armour of those years it was pretty much in straight shape. In those years it was not possible to make layered armour in funny rounded shapes.

Homogeneous armour steel was not just easier and cheaper to produce, but also it could be produced in much bigger numbers, while layered or cemented armour was times tougher.

As funny as it sounds but there is no certain documented data regarding exact type of steel used on German WWII tanks. All we have publicly are just some reverse engineering test performed by laboratories. So here it all depends on approach. When it comes to laboratory all you can say “I have a reason to believe”, anything else will be speculation. So according to Soviet tests I also have a reason to believe that at least PzKpfw III, PzKpfw IV and at least early PzKpfw V were made using cemented steel. Exact make of steel is unknown, KC n/A types are closer by chemical composition. You never know but Ww and Wh steel also could be used on the sides or at the rear, because Ww and Wh is times more easier to weld. But let’s concentrate on frontal armour.

According to 1940 Soviets reports (Kubinka) 32 mm cemented armour used by Germans was equal to Soviet 42-44 mm rolled rolled homogeneous steel. As cruel as it was but they had to admit, that depending on application Panzer III Ausf. H is armoured as good as T-34/76. When it comes to Panzer III Ausf. J it was even more serious tank. In 1941 main soviet anti tank gun was 45 mm anti-tank gun M1937 (53-K). According to tests using even best Armor-piercing shell soviets had in 1940 – 1941 this gun had a difficulties to penetrate Panzer III Ausf. H from the distance of 150-200m, at a distance of 500m Panzer III Ausf. H became invincible.

If to read only what I managed to tell you so far you may ask me why German tank crews feared T-34 at all). Well there was the reason, but to understand it we need to have a look at the steel makes used in Soviet Union. Also to have a look at one more tank.

In 1933-1934 Soviets were building BT-5 tanks and they used two different types of armoured steel. One from Izhorsk factory named “ПИ” and the second type of steel came from Mariupol factory, named “МИ”. “МИ” armoured steel was double layered compound type. Ancient technology for the rest of the world, but even such a small step was a big advance for Soviets. To be frank in 1932 Mariupol factory tried to make cemented armour, but after couple of failures they decided in favor of compound type steeel. In general “МИ” armoured steel was better than its competitor, but Mariupol factory struggled to produce it without defects and also it was expensive. So it was decided to use just “ПИ” type armoured steel.

“ПИ” produced by Izhorsk factory Homogeneous armour steel, but they also had cemented armour steel (I will call it type X, because there is no name for it) and it was used till 1940 to buld T-26 and T-28 tanks). The trouble they experienced was welding. It was very difficult to weld that steel.

When it comes to Mariupol factory after abandoning double layered compound type steel they started to produce “Bullet Resistant” ( not a shell resistant) Homogeneous armour steel “ИЗ” (also invented at Izhorsk factory), something that later on became “2П” and supposed to be used just at the bottom of T-34 and non critical armoured parts.

Also Soviets had another light tank T-50. It also used mysterious type X cemented steel. Same as with T-28 Soviet workers had no clue how to weld it. But when it comes to armoured protection of T-50 it was impressive. Produced in small numbers in 1941 – 1942 its 37 mm armour was equal to T-34 45 mm armour.

So officially Soviets used mysterious type X cemented before T-34 production and also used it in 1941-1921 on T-50… but for whatever reason not on T-34. the only reference I managed to find is that Izhorsk factory managed to duplicate and to produce Krupp cemented armour in somewhere in 1913. No further records found.

To add a bit more mystery having a look at the main armour of T-34 it was used “8C” type of steel. The only trouble it was made just in late 1941. So what Soviets used till that time? According to one of Nizhny Tagil factory engineers T.Davidkov initially for production of T-34 it was used some kind Chrome-Nickel-Molybdenum armoured steel. Unfortunately he does not mention exact name. Only after German attack when soviets run out of non ferrous metals and there  was a need to come up with something else. And so they did. Instead of making very expensive and difficult Chrome-Nickel-Molybdenum armoured steel they re modified “ИЗ” steel, or in other words “Bullet Resistant” “2П”. Something should not be used as the main armour. To make it look more important it was named as “8C” we know already. The only Chrome-Nickel-Molybdenum armoured steel soviets had at that time was фд-7924. There are no references  where it was used or its composition. The only reference I managed to find is soviet laboratory test about Matilda II armour. All it was said that Matilda II armour was very close to фд-7924 steel.

So here is the answer why first T-34s were so mega expensive  and also why they were feared. They simply used the different armoured steel. As soon as Soviets run out of proper steel feared T-34 became a card board and urgently needed up armouring.

1942 stz 5

 If you still have an interest here is the next part