9% Ni steel is W( Ni) -9% reduced carbon medium alloy relieved as well as tempered steel established by the American International Nickel Company in 1944. Its framework is Martensite and Bainite. This steel has good toughness and high stamina at very low temperature level, the thermal expansion coefficient is tiny compared to Austenitic stainless steel as well as light weight aluminum alloy, the lowest temperature can reach a 196 ℃. The 5% Ni steel established based on 9Ni steel additionally has great low temperature toughness at the low temperature of -162 ~ -196 ℃.
The major qualities of this steel are high nickel web content, high purity, high strength, high reduced temperature level impact durability, excellent weldability. In 1952, the initial 9Ni steel storage tank worldwide was taken into use in the United States. In 1960, the research study confirmed that 9Ni steel without post-weld stress alleviation warm treatment could be utilized securely. Ever since, 9Ni steel has become one of the major materials used in the manufacture of big cryogenic tank. The first LNG storage tank constructed in Japan in 1969 has an optimum capability of 20 × 104m ³.
www.wldsteel.com is the commonly used shape for this steel, and the steel plate have some specification worldwide such as ASME: SA-353, EN 10028, JIS G3127, GB 24510 and others.
EN 10028-4: X8Ni9+ NT640/ X8Ni9+ QT680.
JIS G3127: SL9N520/SL9N590.
ASME: SA-353/ SA-553-1.
GB 24510: 9Ni490/ 9Ni590A.
The mechanical residential properties of 9Ni steel at reduced temperature mainly depend on its chemical make-up, specifically the contents of Ni and also C. On top of that, the sturdiness of 9Ni steel additionally depends on the purity and microstructure of the steel. The 8.50 ~ 9.50 Ni material ensured the hardenability to a specific degree. The reduction of carbon material can significantly lower the rainfall of carbides in toughened up martensite, therefore enhancing the low temperature durability, while the high carbon web content will lead to major deterioration of welding homes and cold weak homes. Therefore, in the alloying procedure, the material of C need to be purely controlled to maintain it in the reduced carbon variety, and at the exact same time, the material of P, S, Mn, Mo, Cr and other alloying components need to likewise be controlled in the reduced array. The content of alloying components and also contamination is a vital factor influencing the weak change temperature level of 9Ni steel.
We know that the liquefaction temperature of gas is -162 ℃, as well as the volume of liquefied natural gas (LNG) is 1/600 of the aeriform state, which has higher demands on the product of LNG tank. Currently the products used in LNG container mainly are 9 Ni steel, 5 Ni, Austenitic steel, Aluminium magnesium alloy steel, etc., as well as the most affordable temperature level can reach 9 Ni steel - 196 ℃, its high stamina, excellent low temperature level durability, great welding performance, simple to refining advantages, making it extensively made use of in the manufacture of LNG tank as well as transport ships, is the best of the cryogenic setting using the toughness of products.