readx; Protection and survivability have always been the most significant performance strengths of the German ship, which is related to the design idea of the German Navy, since the previous dreadnought era, the German ship has always been the world's most important defense warship. Pen @ fun @ pavilion wWw. ｂｉｑUｇE。 The Germans not only strengthened the defense of warships in terms of technology, but also increased the priority of warship defense in terms of design trade-offs: the "Bismarck" class was the battleship with the largest proportion of armor among the battleships built in the World War II era, and the total weight of the armor without the rotating part of the turret reached 41.85% of the standard displacement; it was also the battleship with the largest protection scale in the World War II era, and the side walls of the main armored fort covered 70% of the waterline length and the entire freeboard height.

The "Bismarck" class battleships were mainly built using the following types of steel:

ST42 shipbuilding steel, improved in 1931 from the traditional No. 2 shipbuilding steel, was used to build Bismarck's superstructure and non-armored cabin hull structure. Its hardness is 140-160HB, tensile strength is 420-510MPa, yield strength is 340-360MPa, elastic deformation range is 21%, and its performance is not lower than similar products in other countries.

ST52 shipbuilding steel, improved in 1935 on the basis of the famous No. 3 shipbuilding steel, was used in the construction of the Hull Structure of the Bismarck's armored and lightly armored compartments. Its hardness is 160-190HB, tensile strength is 520-640MPa, yield strength is 360-380MPa, elastic deformation range is 21%, and it has excellent toughness and ductility, and has strong resistance to fracture and tear. Although its softer material is less resistant to kinetic armor-piercing projectiles, it has excellent structural strength retention and excellent resistance to torpedo blasting blast blasts.

WW highly elastic homogeneous steel, invented in 1925 on the basis of the traditional KNC armor, was used in the construction of Bismarck's main anti-mine armor. Its hardness is 190-220HB, tensile strength is 650-750MPa, yield strength is 380-400MPa, and the elastic deformation range is 25%.

Wh high-strength homogeneous steel, invented in 1925 on the basis of traditional KNC armor, the high-performance part of which was used in the construction of all horizontal armor and head and tail waterline armor belts of the "Bismarck" class, as well as internal longitudinal and horizontal armor. Its hardness is as high as 250-280HB, the tensile strength is 850-950MPa, the yield strength is 500-550MPa, and the elastic deformation range is 20%.

K/A surface carburized hardened steel, developed in 1928 on the basis of traditional KC armor, was used in the construction of Bismarck's broadside, gun mount, turret façade, and conning tower façade armor. Its surface hardness is as high as 670-700HB, the decreasing carburizing depth is 40-50%, the substrate hardness is 230-240HB, the tensile strength of the substrate is 750-800MPa, and the yield strength of the substrate is 550-600MPa.

In the longitudinal top view, the Bismarck-class hull is spindle-shaped, with the thickest in the middle, tapering in a parabolic shape towards the ends of the head and tail, and this form of hull can easily obtain reliable structural strength. Transversely, due to the arrangement of heavy upper side armor and upper armor deck, the ship has arranged the first main structural beam below the upper deck and the second main structural beam below the second deck, so that the ship has a double-layer upper main structural beam on the hull, instead of a single main structural beam under the main horizontal armor as is the case with most warships of other countries. The advantage of this is that the main load-bearing structure is arranged by making full use of the scale of the cross-section of the hull of 25 meters high and 46.8 meters wide, which maximizes the geometric moment of the load-bearing structure and thus improves the strength.

The "Bismarck" class is divided into 44 main watertight compartments, from the 6th to the 38th compartment of the main armored fort area, the main armored fort of the hull is 246.15 meters long, the widest point is 46.8 meters, protecting 70% of the waterline length and 85%-90% of the buoyancy and reserve buoyancy space, which is a big deal that no warship of the same period can do. Inside the huge hull main armor fort, the Germans in turn installed multiple armor and watertight partitions in the longitudinal and transverse directions. For example, in addition to the 11-meter-wide mine-protected isolation compartments on each side of the boiler compartment, the lower part of the boiler compartment is divided into three watertight compartments arranged side by side, each of which houses two high-pressure heavy oil boilers, and Bismarck has two such compartments, which are separated by a secondary artillery ammunition depot section. With such an arrangement, one boiler compartment is flooded, and the battleship will lose only one-sixth of its power, and an attack from one broadside direction will only flood the battleship's two boiler compartments at most, losing a third of its power. In addition, unlike the battleships of other countries, relying on a large amount of lateral, longitudinal and horizontal armor, the ship also has a large number of watertight compartments in the upper hull above the main horizontal armor. Together with the lower hull, the Bismarck is subdivided into thousands of separate watertight compartments of various sizes, like boilers, in which each important subsystem is separated and placed in a way that minimizes risk.

The mine protection isolation cabin of the "Bismarck" class is 11 meters deep in the amidship, gradually reduced to 10 meters in the direction of the stern, and gradually reduced to 9 meters in the direction of the bow of the ship, and is composed of 44mmST52 hull-air cabin-36mmST52 oil bulkhead-oil tank-90mmWW main anti-mine armor plate-16mmST52 waterproof back plate, which is an arrangement structure of two cabins and four layers of steel plates. The structure does not have a complete filter compartment behind the main anti-mine armor of the power compartment section, and between the main anti-mine armor of the auxiliary gun ammunition depot and the main gun ammunition depot section to the ammunition depot wall, the pipeline compartment and the storage compartment below form a complete filter compartment. On the whole, in addition to the relatively tight arrangement of the ammunition depot compartments, compared with the mine protection structure of the battleships of other countries in the same period, the structure of the "Bismarck" class is much simpler, and the design requirements are not high, only to resist the underwater blasting of 500kgtnt. However, the German Navy's Technical Report No. 222-45 of November 12, 1944 on the loss of the "Tirpitz" pointed out that its TDS could withstand the underwater blasting of 600 kg of German Hexanite high explosives, which can be considered to be the actual and accurate level of defense of the anti-mine system of this class of warships.

The main armored fort of the "Bismarck" class is 246.15 meters long, covering 70% of the length of the waterline, and the side walls of the armored fort extend from more than 6 meters below the waterline to the upper armored deck, and the common shelled parts of the entire broadside façade are arranged with heavy armor, which is the battleship with the largest proportion of armored coverage area in the World War II era. The upper 5.2-meter-high broadside armor belt is made of 290mm thick K/A steel plates, which, together with the 100-160mm upper armor deck, protect the entire sailors' living and working areas located in the upper hull of the main armored fort, and can withstand heavy cruiser shells and small and medium-sized aerial bombs. In the middle is a 640 mm thick and 10.4 m high K/A steel plate made of the main side armor belt located above and below the waterline, which can withstand most of the battleship's shells on its own with material quality superiority at normal engagement distances. At the normal combat weight of 19.6-20.8 meters of draft, Bismarck's 10.4-meter-high 640mm broadside armor has 5.5-6.4 meters buried underwater, and below the 640mm mainboard side armor, there is also a 1.2-meter-high and 340mm thickness of the lower edge of the mainboard side armor, so that the ship has 6.4-7.6 meters of broadside armor down to the water, providing it with good underwater bulletproof capabilities, the shell must travel a long distance in the water to hit a lower position before it can pass through the 44mm hull into the anti-mine swallowing capsule and absorption capsule, at this time the 90mm main anti-mine armor plate behind has been able to resist independently。

Inside the main armor fort of the hull, located below the main armor deck, there are 16 transverse internal armor walls made of 40-120 mm thick WH steel plates, which are also part of the transverse structure of the hull at the same time. The 16 armor walls and the 640mm thick transverse outer armor walls at the head and tail end of the "Bismarck" class divide the lower space in the "Bismarck" class main armor fort into 18 heavy armored compartments, 12 of which extend to the upper hull with a thickness of 60 mm, and the 200-440mm thick transverse outer armor walls at the head and tail ends together divide the upper space in the main armored fort into 14 heavy armored compartment sections. Even if a battleship shell or armor-piercing bomb was fired into it and exploded, the shrapnel was blocked by these internal armors, and the destructive power would be controlled in a smaller area of space.

The bow and stern waterlines of the Bismarck-class are equipped with light armor belts made of 120mm and 160mmWh steel, respectively, which will maintain the overall integrity of the waterline shape as much as possible when the hull is attacked, and prevent large-scale fragmentation of the hull surface. Most of the new battleships of the World War II era used the method of key protection to arrange their armor, because their armor has a small specific gravity, there is no extra armor to protect non-lethal parts, and it is the first thing to ensure that the key parts are not penetrated.

The main horizontal armor of warships in most countries during World War II was arranged above the main side armor, and was connected with the upper edge of the main side armor to form a closed armor box. The German ** ship is different, it adopts an armor arrangement called the armored fort extension structure, its main horizontal armor is located at the waist of about half of the main side side armor, and slopes down at both ends near the side of the side at a small depression angle, extending to the lower position of the main side armor to connect with it, such that the main horizontal armor looks like a dome in cross-section, called "dome armor". The top of the dome is located near the waterline, and when the warship is in normal combat displacement, it is often below the waterline, which makes it necessary for enemy shells to pass through this layer of armor after passing through its main armor belt before entering the German ship's engine room, boiler room, secondary gun ammunition depot, and main gun ammunition depot. Although the dome arrangement reduced the spatial height of the core compartment of the ship, this problem was often compensated for by the huge length of the main armor area of the German hull, thus maintaining the total space of the core compartment of the German ship. Taking the Bismarck battleship as an example, its 460mm main gun ammunition depot, boiler, engine, 150mm auxiliary gun ammunition depot, 105mm, 37mm and 20mm anti-aircraft gun ammunition depot, steam transmission pipeline from the boiler room to the engine room, and the longitudinal main cable channel running through the whole ship are all arranged under the 160-240mm dome armor, accommodating more facilities than most of the new battleships of other countries.

German battleships did not have the habit of having dual-purpose decks, they adopted the traditional layout of the separation of armored and watertight decks. The horizontal structure of the hull of the "Bismarck" class, located above the engine room and ammunition magazine, has three layers, the first layer consists of teak + 100-160-mmwh armored deck + 20mmST52 watertight deck + first main structural beam; The second layer is composed of a 40mmST52 watertight deck + a second main structural beam; The third layer is one of the few innovative designs on the ship, under the 160-200mmWh horizontal part of the armored deck is a 40mm ST52 watertight deck, and further down there is not a main structural beam like the battleships of other countries, but a layer of structural stiffeners is laid horizontally, which is used as an integral part of the hull structure together with the armored deck, assuming a similar role to the main structural beam. In addition, the structural stiffeners are made of ST52 steel, which has an elastic deformation range slightly larger than that of WH steel, which can undergo elastic deformation with the WH armor plate and share the peak tensile force, and then recover with the WH armor plate, so as to improve the defense of the entire horizontal structure and strengthen the last line of defense to protect the power compartment and ammunition depot.

The "Bismarck" class has two 3-pack 460mm main turrets in the front and rear, the open part of the gun mount is a 640mm thick K/A armor steel ring, the part between the 160mm upper armor deck and the 200mm main armor deck in the ship is a 440mm thick K/A armor steel ring, and the outer sides are protected by 290-640mm K/A broadside armor and 60mmWh internal longitudinal armor, with a total thickness of 7901140mm, and the defensive capability is higher than that of the open part of the gun mount.