Armor sample chemistry question

[nautilus]

Hello Experts,

I've seen a lot of knowledge about the composition of naval or panzer armor being shared in this forum so I thought I wanted to post this question ... a "reverse lookup" if I may. I acquired a sample of steel armor some time ago, allegedly from the Tirpitz. I recently got a chemistry analysis done by a metallurgy lab and received the following results:

Carbon ... 0.51%
Manganese ... 0.85%
Silicon ... 0.52%
Phosphorus ... 0.027%
Sulfur ... 0.023%
Chromium ... 2.05%
Nickel ... 1.91%
Molybdenum ... 0.004%
Copper ... 0.03%
Vanadium ... 0.04%
Cobalt ... 0.03%

The plate fragment is exactly 3 cm thick, so not the main armor, but possibly a torpedo bulkhead(?). I was wondering if anyone would be able to identify or narrow down the type of steel this could be (Krupp non-cemented, Wotan, KCA, naval or panzer, other country?). The Chromium-Nickel balance suggests Krupp armor for thin plates, but the C, Si, and Mn contents are high. Appreciate any insight and pointers to references anyone may have, including old specs in german! Thanks in advance.

[Thorsten Wahl]

looks like a steel for armour piercing projectiles
-high C %- required for hardenability ~60 Rc

post 1941

...P and S content appears as to high max 0,02% were allowed

[Mostlyharmless]

I am sure that most of you know already but there was a 30 mm bulkhead extending the 45 mm anti-torpedo bulkhead from the main armoured deck up to the 50 mm weather deck. Most of that would probably be as originally built but it is just possible that something needed repair after the FAA bomb attacks in 1944 and thus it might just be 1944 steel.

[Thorsten Wahl]

30 mm could be the longitudial splinterbulkhead
But it makes no sense to use a 0.6 % C, 2 % Ni / 2 %Cr alloy here. For such thin plate. You dont need extreme hardenability.

And 0.6 % C could be somwhat problematic for welding.

[hans zurbriggen]

Hello,
I post here my question even if not directly related to initial post.

Reading M.J.Whitley "German Capital Ships of WWII", pag.20, there is very detailed description of steels and thicknesses used in Deutschland Panzerschiff.

Among steel descriptions there is 'K.C.s' Krupp Cemented (not n/a, I understand) that is defined as 'weldable'.
Is this correct or just an error ? How can cemented armor be welded without degradating its charateristics (hardening process) ? Was this K.C. the same used during WWI or intermediate between WWI and K.C. n/a ?

Several other types of steels are mentioned as used in Deutschland too: 'Wh n/a', 'Ww n/a' but also 'N' and 'S' defined as special steels (N = low nichel) that I did not know, and SII and SIII as construction steels. Can anyone explain their charateristics ? Are they included in the table kindly posted by Mr. Wahl ?

hans

[Thorsten Wahl]

Schiffbaustähle were not alloyed steels

Schiffbaustahl I = St 37
Schiffbaustahl II = St 42
Schiffbaustahl III = St 52

they exist until today a SAE-steels
multiplicate 9,81 and u get the figure in N/mm² instead kg/mm²

n/a means neue Art = new type

KC witout any abbreviaton general Krupp cemented
KVC Krupp shortened cemented
KNC Krupp not cemented

KC (aA) krupp alte Art old typ reference to WW1 KC
KC (nA) Krupp neue Art WW2 KC

Wotan only used in WW2 it didnt require nA usually
Wotan W weich
Wotan h hart
Wotan sh starr

[hans zurbriggen]

Hello Mr. Wahl,
thanks for explaining Schiffbaustähle charateristics and equivalence.

This is the list of steels used for Panzerschiff A according to Whitley (he was apparently using his own names/abbreviations for steel types):

Steel_Types.JPG (46.55 KiB) Viewed 5980 times

My doubts are still about :

1) 'weldability' of 'K.C.s' steel, indicated by Whitley as the one used for turret fronts (140 mm), barbettes (100), conning tower (140 mm). Was this KVC? Still no idea how it could be welded: I suspect a typo in Whitley book.

2) 'K.W.s' steel: is this homogeneous steel ('equivalent' to Class 'B' steel) ? In this case it might have been weldable (which max thickness?). Whitley sais it was used for sides and roof (30-85 mm), rear (170) and base of turrets (30-80)

3) N and S steels (both mentioned as armor or at least special steels). N is indicated as the armor steel used for belt (50-80mm), armor deck (30-45) and rear of turrets (170), S for barbette straps (30 mm) only. Do they appear in the table you have posted in your previous post? Whitley refers to: "Heft B Nr.15 der Materialvorschrift 1915" and "Heft B Nr.29 der Materialvorschrift 1915".

hans

[Thorsten Wahl]

1) 'weldability' of 'K.C.s' steel,

Krupp weldable is KNC
but not cemented
as C content is in the order of0,32 -0,34%

in therory the backside of KC is weldable but it wasnt done
the abbreviations were partly old (WW1) abbreviations

MDV 147 Allgemeine Baubestimmungen I Nr. 47 Liefervorschrift für Panzermaterial
https://drive.google.com/file/d/0B12aaM ... igTaUscvBA

[hans zurbriggen]

Hello Mr. Wahl,
thanks for info and document.

hans

[hans zurbriggen]

Hello,
it looks like (at least for Panzerschiff A) Germans used several types of steels, even some WWI vintage materials (possibly also due to reduced thicknesses), while with Scahrnhorsts and Bismarcks they adopted WWII (n/a) steels for armor. Is my understanding correct?

hans

[Thorsten Wahl]

Yes,
Deutschland had older types.
These were replaced by the newer types on Scheer and AGS

[hans zurbriggen]

Hello Mr.Wahl,
thanks for confirming the difference between Panzerschiffe.
Do you know which were the charateristics and performances of the armor grade steel defined by Whitley as 'N' (Low Nichel armor steel Heft B Nr.29 der Materialvorschrift 1915), used for belt and transverse bulkheads of Deutschland in comparison to the Wh n/a (used on Scheer and AGS) and the reason for choice of 'older' steels on such an important ship for the 'resurrecting' German Navy?

hans

[Herr Nilsson]

...(he was apparently using his own names/abbreviations for steel types):
...

K.C.s = Krupp, cementiert gehärtet, schwierig
K.W.s = Krupp, weich, schwierig
N = niedrig prozentiger Nickelstahl
S = Sonderstahl

[hans zurbriggen]

Thanks Mr. Nilsson,
do you know whether schwierig is referred to complexity in production or difficulty in weldability ?

hans

[Herr Nilsson]

No