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Post Info TOPIC: A7V Armour Plate properties


Legend

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A7V Armour Plate properties
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Found some French work on the physical properties/ composition of the armour plate on A7V #542.

The steel is a Nickel steel with about 4% Ni - it's roughly like a low alloy tool steel. It was pretty hard -

the hardness test result is about the same as white cast iron.

If anyone's interested in the detail I'll translate the whole thing and post it.

Regards,

Charlie

Edit: wrong - too many years since I did this stuff - the composition is very similar to modern case hardening steels.  



-- Edited by CharlieC on Wednesday 22nd of March 2017 01:21:02 AM

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Captain

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Hello Charlie

The Frenchs have done some tests on the A7V # 542 Elfried to see the strength of the armor ( Shooting with 37 mm Bethleem and Puteaux / 8 mm Lebel standard and armor piercing...)

Tanker wrote some articles about this.

You will find the trials and conclusions  in :

http://pages14-18.mesdiscussions.net/pages1418/Pages-d-Histoire-Artillerie/Artillerie-Speciale-chars-d-assaut/elfriede-recupere-bretonneux-sujet_463_1.htm

It is in French but I am sure you can find a means of translation.

Best regards

Olivier



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Lieutenant-Colonel

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Here is an extract from a British report on the analysis of steel taken from Elfriede.

Regards,

Marc



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Regards, Marc

Digital History Archive



Lieutenant-Colonel

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I'd personally be very interested to see that information Charlie.

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Legend

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The data comes from "Ecole d'application des chars de combat. Technique des chars et de l'automobile. Troisième Volume. Armement et blindages 1926"

Composition

The data compares the steel composition of 3 armour steels, one of which is sampled from a 16mm plate from A7V #542.

I've also added data from a modern case hardening steel EN36A nominal composition

 Sample 1Sample 2A7V #542EN36A
Carbon0.35%0.4%0.36%0.13%
Nickel4%3%4.1%3.4%
Chromium1.8%0.4%0.7%0.85%
Manganese  0.4%0.5%
Silicon  0.11%0.25%
Sulphur  0.04%0.02%
Phosphorus  0.02%0.02%

The physical measurements from the A7V plate are:

Elastic limit - 139 (unfortunately the units are not specified)

Tensile strength - 141

Elongation - 6%

Brinel hardness (3000kg) - 400 (typical of white cast iron - **)

I think the conclusion can be drawn that the steel is quite hard but also fairly brittle - the physical properties are different

from the 30mm plate tested (earlier post) which may indicate the problem of creating thin armour plate by carburising - the harder

the plate gets the more brittle it becomes since the depth of the high carbon zone is a greater % of the thickness of the plate.

It's also interesting that the other samples quoted here are fairly similar to the A7V plate composition. 

How effective was the A7V armour? Very - I've seen the A7V #506 Mephisto up close and the armour is marked by dozens of bullet

strikes - none of which did anything more than mark the surface. 

Regards,

Charlie

** - cast iron comes in two flavours - grey which is soft and malleable and white which is hard and brittle - the names come from the appearance of a freshly

broken surface. 

 



-- Edited by CharlieC on Thursday 23rd of March 2017 12:56:15 AM



-- Edited by CharlieC on Thursday 23rd of March 2017 01:03:18 AM

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