X8Ni9 steel for low-temperature LNG storage tanks

Grade X8Ni9 is a European standard low-temperature vessel steel plate, containing 9% Ni. This steel is mainly used for the manufacture of low-temperature LNG storage tanks and belongs to low-temperature steel. It is a low-carbon quenched and tempered steel with a martensite and bainite structure.
Standard: EN10028-4: 2017
Main properties of X8Ni9 steel plate
The main characteristics of X8Ni9 steel are high nickel content, high purity, high strength, high low temperature impact toughness, and good welding performance.
 
Delivery status: delivery in normalizing plus normalizing plus tempering and quenching and tempering status. For steel plates with a thickness of less than 15mm, the delivery status of +N plus +NT is also applicable.
Ultrasonic flaw detection of X8Ni9 steel plate
Ultrasonic inspection standards are implemented in accordance with JB/T4730.3, GB/T2970 or GB/T28297.
 

Heat treatment analysis of X8Ni9 steel

a. With the increase of tempering temperature of X8Ni9, the content of reverse transformation austenite in the steel increases, and the low-temperature impact toughness increases. At the same time, the matrix structure is purified, and the strength first increases and then decreases.
b. When tempering at 580℃, as the holding time decreases, the strength of the steel increases, while the plasticity and toughness decrease, and the plasticity is lower than the standard value; the tempering process of QLT heat treatment is 580℃×60min.
c. With the increase of tempering temperature of X8Ni9, the content of reverse transformation austenite in the steel increases, and the low-temperature impact toughness increases. At the same time, the matrix structure is purified, and the strength first increases and then decreases. When tempering at 580℃, as the holding time decreases, the strength of the steel increases, while the plasticity and toughness decrease, and the plasticity is lower than the standard value; the tempering process of QLT heat treatment is 580℃×60min.
 
 
Application scope:
EN10028-4 X8Ni9 steel plate is mainly used to manufacture liquefied natural gas (LNG) storage tanks and transport ships. The service temperature can reach -196℃. It has high strength, excellent low temperature toughness, and good welding performance. It is a material with good toughness for use in cryogenic environments.