Submarine steel

from Wikipedia, the free encyclopedia

As mangalloy are special types of steel called, are distinguished by high strength and corrosion resistance , especially against sea water , and the lack of any magnetisability distinguished. In addition to their original purpose as a cover for submarines , they are also used, for example, for diving watches .

particularities

Compared to simple stainless steel , submarine steel is still alloyed with manganese and molybdenum . This stabilizes the austenitic structure and prevents the formation of α or δ ferrite . A submarine built in this way can no longer be located by distorting an external magnetic field . Furthermore, the dreaded stress corrosion cracking in contact with sea water is prevented.

The submarine steel is therefore a full austenite with extremely high strength and of the highest non-magnetic quality. The strength value reaches more than 155% of a normal watch case steel AISI 316L. Submarine steel is “completely” resistant to permanent contact with seawater. In addition, due to its ductility, submarine steel is extremely crack-resistant.

Manganese also causes a significant increase in hardness and strength without impairing the toughness , as it inhibits the movement of the dislocations necessary for any plastic deformation . By Kolsterizing , Vickers hardnesses of up to approx. 1300 HV 0.05 can be achieved on the surface .

Examples

The following examples show typical properties of some submarine steels:

Material number Short name Yield point (Re) Tensile strength (Rm) annotation
1.3813 X 40 Mn Cr N 19 ≥ 295 N / mm² 740-920 N / mm²
1.3952 X 2 Cr Ni Mo N 18-14-3 ≥ 295 N / mm² 590-780 N / mm²
1.3964 X 2 Cr Ni Mn Mo N Nb 21-16-5-3 ≥ 365 N / mm² 700-950 N / mm² From class 206 standard for German submarines
1.3974 X 2 Cr Ni Mn Mo N Nb 23-17-6-3 460 N / mm² 800-1050 N / mm²
1.0577 St 52-3 265 N / mm² 450-600 N / mm² Comparison value. Not today's submarine steel, but was used
for submarine class XXI during World War II . Significantly magnetic as martensite.

See also

swell

  1. ↑ Sinn - watch encyclopedia
  2. ↑ EZM - Non-magnetizable steels
  3. ^ Heinrich Schütz: Only the past or already history - the steel crisis in German submarine construction. (PDF) 2009, accessed April 16, 2017 .