Welding Processing of Medium-Manganese Austenitic Steels for Cryogenic Applications

Abstract

For several years, the significance of gaseous energy sources (e. g. liquified natural gas and hydrogen) has been increasing worldwide due to environmental and climate policy requirements. Storage and transportation of the liquids occur under cryogenic conditions. This results in specific requirements for the mechanical properties of the materials used at cryogenic temperatures. Nowadays, cold-tough, high-nickel austenites and martensitic steels of type X8Ni9 are used for such purposes. While austenitic materials offer good processing properties, they are not attractive due to their comparatively low strength and high costs. Welding martensitic steel with commonly used nickel-based additives significantly impacts processing quality and process automation due to high magnetic remanence. Additionally, the increased requirements for the storage of liquid hydrogen regarding low-temperature toughness push the conventional low-temperature materials to their limits. A potential solution to the identified challenges can be achieved by using medium- and high-manganese austenitic steels. Within the scope of this work, the medium-manganese steel X2CrMnNiN1775 (1.4371) is investigated as an economical substitute for the conventionally used materials in cryogenic applications. Considering the relevant qualification requirements for welded joints and welding additives, submerged arc welded joints are investigated and their applicability under cryogenic operating temperatures is demonstrated.