Tuesday 19 May 2020

Cast vs Rolled

The question of cast vs rolled armour is often encountered in specialist literature. It is typically accepted that cast armour needs to be about 10% thicker to provide the same resistance as rolled armour. This was the case with T-34 turrets: cast ones had a nominal thickness of 52 mm, turrets welded from rolled armour had a thickness of 45 mm. However, trials were held in late 1940 to confirm this theory. Defective hulls and turrets rejected by QA were used.

Results of trials with different types of shells were compared to determine the limit of partial penetration (PTP) and limit of complete penetration (PSP) in meters per second.


Considering that the muzzle velocity of the model 1937 45 mm gun is only about 750 m/s (depending on the round), the gun can only penetrate either the cast or welded turret from nearly point blank range. The sharp tipped round fared a little better, but the penetration range for both types of turret is comparable. The 76 mm gun used in this test was the model 1902/30 gun with a muzzle velocity of 650 m/s. Penetration was definitely possible, but also at close range. Note that the casts turrets are actually better at resisting this gun than the welded turrets.

In general, the commission came to the conclusion that the two types of turrets are generally equivalent in resistance to shell fire. 


5 comments:

  1. In terms of cast armour resistance- that's interesting citation from article about "75 mm Sherman tank casualties" - "REME, 5 Gds Armd Div state that an AP.300 and an AP.500 Browning both fired at 100 yds range, penetrated 1/2 and 1 1/2 inches respectively into the turret armour"

    I heared abour bad quality of early US cast armour and in my opinion citation above can be described as proof (IIRC, 7.62 mm ammunition typically can't penetrate 1 inch armour). https://scholars.wlu.ca/cgi/viewcontent.cgi?article=1422&context=cmh

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    1. My mistake- "AP.300" penetrate 1/2 inch armour, not 1 inch armour. But "AP.500 Browning" penetrate 1 1/2 inch armour- that's better penetration than it's nominal penetration.

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    2. The troops definitely seemed to think so https://i.imgur.com/6g6UK2b.png

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  2. What was this sharp nose 45mm shell and was it used during the war?

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    1. The leftmost one in this picture https://forum.guns.ru/forums/icons/attachments/19212.jpg

      It pops up in documents every so often, so presumably it was still used.

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