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...)
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 1
Sample 2
A7V #542
EN36A
Carbon
0.35%
0.4%
0.36%
0.13%
Nickel
4%
3%
4.1%
3.4%
Chromium
1.8%
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
