Investigation of welded joints on a medium-manganese steel for use under cryogenic conditions as an alternative to 9% Ni steels

The importance of technical gases has been increasing worldwide for several years. Liquefied natural gas for shipping and land-based transport are becoming increasingly important, especially as a result of political requirements to reduce emissions and climate targets. The significantly increased storage efficiency due to lower volumes means that transport and storage are mainly carried out in a cryogenic condition. However, these conditions imply special requirements for the materials used. In recent years, the 9% Ni steel has been increasingly used for cryogenic applications. This is due to the significantly higher strength properties and the resulting mass reduction compared with cold-tough high-nickel austenitic steels. In addition to the comparatively low strength of high-nickel austenites, the higher prices and susceptibility to raw material market-based price fluctuations make the materials economically unattractive for use with high material requirements. The increased requirements of liquid hydrogen storage for low-temperature toughness are pushing the conventional low-temperature materials used to their limits. For the qualification of medium manganese austenites for the maritime applications, the welding processing of an X2CrMnNiN17-7–5 is investigated and compared with results of the 9% Ni steel.