Effective Resistance of T34 Hi-Hardness Plates

[rexford]

Spring 1942 German firing tests against T34 armor suggest that 40mm to 53mm high-hardness plates would resist hits by 37mm AP like the plates were made of medium hardness armor but the effective resistance would be 26% higher.

Thus, when 37mm AP hits the 45mm at 40 degree side hull of a T34 the armor resistance would be calculated using the standard slope multipliers but the result would be multiplied by 1.26. So the 45mm flat area on the T34 mantlet would resist 37mm AP hits like 57mm of medium hardness rolled plate.

The firing test results with 50mm AP do not result in clearcut results for hits on the 45mm at 40 degree side hull, since the majority of the hit angles vary from 55 to 65 degrees from vertical and the two hits at 40 degrees appear to be shatter gap failures due to uncapped 50mm AP.

Two 50mm Pak 38 uncapped AP hits at 100m against 40.8mm armor at 40 degrees resulted in "durchschuss kleine als Kaliber glatt" results, which we think are partial penetrations. The odd thing is that the same rounds fully penetrated 42.1mm plate at 65 degrees at the same range, so why two failures against 40.8mm at 40 degrees?

Are there any combat or firing test results that would add to the above German test results for 50mm Pak 38 attack on the side of a T34? Jentz has something which suggests a 600m to 700m penetration range for 50mm L60 against the T34 side, but additional results would provide a better foundation for penetration models.

Thanks.

Lorrin

[c3k]

Rexford,

Your post seems to state that the T-34 armor can be more closely modelled using MEDIUM hardness resistance factors rather than HIGH hardness numbers.

What is the approximate ratio of resistance between MEDIUM and HIGH hardness? (I.e., is medium hardness only 80% as good as high hardness against solid penetrators?)

Thanks,

Ken

[rexford]

Originally posted by c3k:

Rexford,

Your post seems to state that the T-34 armor can be more closely modelled using MEDIUM hardness resistance factors rather than HIGH hardness numbers.

What is the approximate ratio of resistance between MEDIUM and HIGH hardness? (I.e., is medium hardness only 80% as good as high hardness against solid penetrators?)

Thanks,

Ken

The resistance of high-hardness armor needs to be converted to medium hardness plate, since penetration data for rolled homogeneous armor is medium hardness.

High-hardness armor is best against small diameter projectiles, and becomes progressively less resistant as the ammo gets bigger. This happens because high hardness armor has low impact resistance and the metal structure is crystalline, which tends to be brittle under strong impacts.

So, when 45mm high-hardness T34 plates are attacked by 37mm AP, they resist like about 57mm of medium hardness plate. Against 50mm APC the T34 45mm plates would resist like close to 45mm of medium hardness, while a hit by a German 75mm APCBC round on a 45mm high hardness plate would be resisted by about 34mm equivalent medium hardness.

This is why T34 45mm plates are so vulnerable to 75mm hits in CMBB. If the T34 carried 45mm medium hardness plates on the front hull and they were good quality, the 45mm/60 degree glacis would resist like 122mm of vertical plate. And 75L43 hits would bounce beyond 600m or so.

But good quality medium hardness plate takes time, care and skilled workers to manufacture, and high hardness allows more tanks to be made with a given workforce.