Review of 9% Ni steel and its weldability

Research and development status of 9%Ni steel for cryogenic liquefied natural gas storage tanks were summarized and reviewed.Microstructures, mechanical properties and field weldability were presented.Most commonly used quenched and tempered 9%Ni steel is composed of a majority of tempered martensite and a few scattered retained austenites.Base metal of 9% Ni steel shows high strength, good cryogenic toughness, excellent field weldability and low cold-cracking susceptivity.Hot-cracking can be avoided under proper welding parameters.A heat input of 7-35 kJ cm and a interpass temperature lower than 100℃ are generally adopted for the welding of 9% Ni steel.