Any Research on the Fate of the Wreck of the Bismarck?

Anything concerning the wreck. Expeditions, submersibles, photos, etc.
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Dave Saxton
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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby Dave Saxton » Sat Feb 20, 2010 11:47 pm

Legend wrote:Titanic is made of a low quality steel with a high content of iron, thus all of the brown-rust stalactites on the wreck. The Bismarck is a high carbon steel. Due to the purer and homogenous state it will last much much longer, because of the low iron content. I see Bismarck lasting longer than any nation currently standing.



The construction steel of Bismarck was ST-52. The composition of ST-52 is:

C-0.14%
Si-0.36%
Mn-1.4%
Cu-0.37%
Balance is FE

The carbon content is relatively low to improve weldability. By comparision the C content of D-steel is 0.30% or 0.23% for DW. Of special interest in this context is the high Cu content. Copper significantly retards corrosion in marine enviroments. It also increases strength significantly. The armour grade steels such as Wh, Ww, and KC, will have Nickel, Chromium, and Molybdenum. These will all retard corrosion to a great extent. I have seen Cr/Mo steels of much lesser alloy amounts than armour grade steel remain shiney for a long time, even exposed to the elements and chlorides. German armour grade steels for naval use also carried 0.11% Cu.

Unless your dealing with a stainless steel or a 60% nickel steel..ect..., even armour grade steel is mostly (more than 90%) Fe. The Bismarck did not use high carbon content in its materials due to weldability concerns. The carbon content of Wh was at most 0.29%.

Of interest is the high % of welding. The heat effected zone of weld seems are prone to corrosion. These areas will likely degrade much quicker if exposed to the elements (paint scaped or burnt off ...ect...). Also the weld metal of weld seems is also more prone to corrosion than the non-heat effected areas of the parent metals. The exception will be welds of armour to armour or armour to construction steel. Here austenic stainless steel was used for the weld metal.

Another interesting aspect of the Bismarck is the extensive use of structural plates 20mm thick. That is a lot of metal to rust out.

What is interesting is that Andrea Doria has basically rusted out and collapsed on itself in many places already.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby Thorsten Wahl » Sun Feb 21, 2010 5:30 pm

St 52 slightly corrections
St 52 is according DIN a high-strenght non-alloyed steel
Contents
C - 0,17% +-0,03%
Si - 0,45% +-0,15%
Mn - 1,15% +-0,25%
Copper content was max 0,55% but this content was deleted from the original Kriegsmarinenorm at around Okt 1943
post war metallurgical literatur states for small amount of copper

unwanted contents
P - < 0,06%
S - < 0,06%
P+S - < 0,1%

Strenght
(kg/mm²)

Thickness (mm) Tensilestrenght- Yield- Elongationlenghtwise-Elongation crosswise
<18--------------------52...62--------36------>24%----------------------->21%
>18...<=30-----------52...64--------35------->23%---------------------->20%
>30...<=50-----------52...64--------34------->22%---------------------->19%

St 52 is mostly comparable to Schiffbaustahl III

St 52 replaces St 37 because of its 50% increase in strength.
So ship-hull-constructions with 40% less steel were possible with simultaneous increase of strenghtproperties
aditional the weldening technolgy saves an additional of roughly 10% material compared to the riveting technology and also increase strength of the connections
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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby Dave Saxton » Sun Feb 21, 2010 7:44 pm

Hi Thorsten,

The specs I used are from a 1942 welding study. I also have the 1933 requirements specs set by the KM. These match your specs more or less. I also have B&V's spec charts for ST-52. I seem to recall them listing ~0.17% C. An interesting aspec from the welding study was the elongation of the St-52 tested:

langs:32.4%
quer:31.4%

The 1933 specs: lists elongation as:
dehnung% 18 bis 20

Schiffbaustahl III 1908 lists the Tensile as 50kg/mm2 and elongation as 16% "wenigstens"

The welding electrode for ST-52 was the E52K. A low hydrogen electrode eqivilent to the modern 7018. The weld metal in the welding study tested:
UTS:52.8
YTS:45.7
Elongation: 27.5%
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby Bill Jurens » Tue Feb 23, 2010 2:37 am

I am sure Bismarck would have survived a Titanic-type iceberg collision easily. Actually, Titanic almost made it herself. What's interesting is that even today most modern cruise-liners would not be able to survive a Titanic type collision either. This type of raking damage is extremely deadly in a single-hull design.

Bill Jurens

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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby RF » Tue Feb 23, 2010 1:47 pm

Bill, I would have thought on these single hull liners the watertight bulkheads would go up to the required deck level to retain watertight integrity, whereas on Titanic I believe they only went up to E Deck (and just not quite high enough)?
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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby RF » Wed Feb 24, 2010 8:54 am

Another thought.

If Bismarck is able to escape a glancing impact on an iceberg with only a small amount of flooding, given the speed Lutjens applied to run the Denmark Strait, if instead of being intercepted by Holland Bismarck had struck a glancing blow with an iceberg instead would it be possible for the berg's underwater mass to cause similar or identical damage as the underwater hit from POW which ruptured the forward oil tank?
I am asking this out of curiousity as I am not a naval engineer.....
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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby hammy » Wed Feb 24, 2010 2:27 pm

The Water-tight bulkheads do not go all the way up to the weather deck (the one you walk about on in the open air) in passenger carriers because it would be useless to have them this high .

Firstly , any ship flooded to the weatherdeck in one or more hull spaces between these bulkheads is headed for the bottom anyway due to stability issues .

Secondly , the hydrostatic pressure at the bottom of the W T bulkheads on either side of the flooded section simply couldn't take the weight of water , you would have to construct them very much stronger than is normally done , and again this would be useless expense , due to the stability issues . And even if you did this , a fully filled section between two empty ones would be very likely to tear the ship apart .

I remember reading a book called "Tanker Practice" written for Merchant Navy cadet Officers which showed you how oil tankers should be loaded and emptied in ships like the big WW2 tankers , where getting this wrong was a certain recipe for rolling her over or breaking her back .
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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby tommy303 » Wed Feb 24, 2010 5:10 pm

Normally, unless you actively pump a compartment full, a compartment will only flood as high as the adjusted waterline reflecting the loss of buoyancy and trim from the increased weight caused by the water. Once equilibrium is reached, the ship will adopt a new waterline and, unless there is progressive flooding in other compartments, the waterlevel in the flooded one will be neither more nor less than the adjusted waterline.

The Water-tight bulkheads do not go all the way up to the weather deck (the one you walk about on in the open air) in passenger carriers because it would be useless to have them this high .


In the previously mentioned Great Eastern of 1859, the bulkheads did go all the way to the weather deck, and while it made the ship safer perhaps, it also was highly inconvenient to the passengers and crew who could not go directly from one compartment to the next, as there were no water tight doors in the design. Instead they had to go up to the weather deck cross over to the next hatchway and descend back down again.

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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby tommy303 » Wed Feb 24, 2010 5:17 pm

RF,

The hit forward was actually above the waterline but below the bow wave. The flooding of the forward fuel tanks was due to severed piping, so the nature of the damage was somewhat different in the two cases. An iceberg would likely only rupture the outer hull plating, and the inner hull plating would suffice to prevent extensive flooding inboard. Unless Bismarck hit head on at high speed, she might not have suffered enough damage to kill the mission.

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They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.

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Re: Any Research on the Fate of the Wreck of the Bismarck?

Postby RF » Thu Feb 25, 2010 2:49 pm

Thanks for the info tommy303.

POW - more deadly than an iceberg!
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