06Ni9DR level is -196 ℃ low temperature pressure vessel steel plate. Is its good low temperature impact properties, and low coefficient of thermal deformation, and is widely used in LNG ships and LNG storage and transportation projects. Same series grades are 08Ni3DR (3.5 nickel), 08Ni5DR (5 nickel), and 06ni9dr (commonly known as the 9-nickel steel). 06Ni9DR cryogenic vessel steel 06Ni9DR, generally called its 9Ni or nine nickel steel, corresponding foreign brands is SA553, SA353,9Ni, Wuyang Steel and TISCO domestic production. GB24510-2009 cryogenic pressure vessels 9% Ni steel inspection execution JB / T4730.3-2005 Nondestructive Testing pressure equipment. Quenched and tempered steel with heat treatment quenching and tempering offline delivery. In order to improve the toughness of steel, can also be an intermediate heat treatment (secondary hardening), of a thickness of not more than 12mm steel plate can also be normalized and tempered state pay twice goods, steel tempering temperature is not lower than 540 ℃. + Electric furnace steel refining method, the steel should be subject to vacuum treatment. 06Ni9DR cryogenic vessel steel 06Ni9DR, generally called its 9Ni or nine nickel steel, corresponding foreign brands is SA553, SA353,9Ni, Wuyang Steel and TISCO domestic production. With the diversification of one of the world's energy resources, the future of the domestic demand for LNG terminal construction materials will be very large, the development of appropriate structural materials will become an important part of energy strategy adjustment: 9Ni steel used in the analysis of the LNG storage tank . LNG temperature is -162 ℃, require structural material which has a certain strength and toughness at very low temperatures. Current ultra-low temperature materials are the following: austenitic stainless steel, nickel-based alloys, aluminum and steel 9Ni. Relative to austenitic stainless steel and austenitic iron - nickel alloys, steel 9Ni lower cost, relative to aluminum, 9Ni steel has better mechanical performance, structural materials LNG storage and transport equipment commonly used internationally 9Ni steel . Which, 9Ni steel is only possible at - 196 ℃ ferritic steel used in low temperature, Charpy its -196 ℃ reached 200 ~ 230J, is toughness at cryogenic environment, the best material to use. 1 9Ni steel material temperature of the LNG storage tank is designed to -165 ℃, the temperature must be considered because of possible condensation with nitrogen during design time, so the design temperature range of -165 ~ -196 ℃. 9Ni steel since the 1940s to develop, because of its high strength, good low-temperature toughness, and the cost of stainless steel is lower than Ni2Cr gradually been widely adopted. 1956 was included in the ASTM standard 9Ni steel. After 1982, 9Ni steel cryogenic tanks became the main material, gradually replaced the Ni-Cr stainless steel, are countries in the world as LNG and atmospheric pressure liquid nitrogen steel equipment. 9Ni ferritic steel is low temperature steel, high strength and good toughness. Based alloy composition, 9Ni steel is the steel, but because of the positioning of its manufacturing equipment design temperature at - 165 ~ -196 ℃ range, so the raw material itself and the factors involved in the manufacture brittle transition temperature is very critical. The main factors affecting the 9Ni steel brittle transition temperature of the grain size, organizational structure, alloying elements and impurities. 2 9Ni chemical composition of the main factors affecting the 9Ni steel brittle transition temperature, the alloying elements and impurities are closely related to the chemical composition. 9Ni steel chemical composition design criteria in Table 1: Table 1 9Ni steel chemical composition element C Si Mn PS Ni ASTM A553 ≤0.13 0.15 ~ 0.30 ≤0.90 ≤0.035 ≤0.04 8.50 ~ 9.50 ASTM A353 ≤0.13 0.15 ~ 0.45 ≤0.98 ≤0.040 ≤0.035 8.40 ~ 9.60 BS1501-509 ≤0.10 0.10 ~ 0.30 0.30 ~ 0.80 ≤0.030 ≤0.025 8.75 ~ 9.75 VDEh680 ≤0.10 0.10 ~ 0.35 0.30 ~ 0.80 ≤0.035 ≤0.035 8.50 ~ 9.50 JIS G 3127 ≤0.12 ≤0.30 ≤0.0.90 impact ≤0.025 ≤0.025 8.50 ~ 9.50 for each alloying elements: C - carbide precipitation can cause pitting, general control <0.08%; Mn-- austenite phase stabilizing element, improve the wear resistance and nitrogen fixation capacity; Si-- help high temperature high temperature oxidation and acid corrosion performance; Ni-- stabilizing element, reduce brittleness and improve the mechanical properties, and enhance the ability of acid. When 9Ni steel plate used, should pay attention to the following aspects: (1) the scope of the chemical composition of the steel 9Ni standards should be strict, such as Si mass fraction of 0.15% ~ 0.30%, Ni content was 8.50% - 9.50%; (2 ) In general, the standard allowable maximum P and S is about 10 times the value of the physical 9Ni steel sheet, that is: ① When 9Ni steel -196 ℃ used when design conditions, must substantially reduce the content of P and S; ②9Ni steel equipment manufacturing requirements as much as possible to reduce the content of P and S, in order to ensure 9% Ni steel devices can meet the design requirements for the use of a temperature of -196 ℃ time. (3) 9Ni steel chemical composition designed artificially added alloy composition and control of the key for Ni and Mn, in the control method of the license conditions, tends to give a larger value. (4) other residual alloy composition should be strictly controlled. Heat treatment of steel 9Ni 3 9Ni ferritic steel is steel under low temperature cryogenic conditions of use, after appropriate heat treatment, impact toughness at 77K has greatly improved. Existing steel heat 9Ni There are three basic norms that normalizing normalizing + tempering (NNT), quenching and tempering (QT), quenching + subcritical quenching and tempering (IHT). Section 3.1 normalizing normalizing + tempering (NNT) 9Ni steel once normalizing for air-cooled 900 ℃, holding time according to the thickness of the decision, which is about 2.4min / mm, but must ensure that the holding time is greater than 15min, the second normalizing air cooling at about 790 ℃, holding time and the first requirement, as is air-cooled or water-cooled and tempered at 550 ~ 580 ℃, holding time and normalizing the same requirements. The purpose of normalizing the austenite grain refinement, finer austenite grain size, the higher the intensity 9Ni after heat treatment of steel and plastic as possible, impact toughness is also higher. However, if the normalizing temperature is too high, or too long holding time at high temperatures, the austenite grain steels will grow, will significantly reduce the impact toughness and crack propagation energy and improve steel brittle transition temperature. Thus, the first normalizing temperature higher than Ac3 or Acm, whose purpose is to refine the grain. Second normalizing temperature slightly, in order to bring about a phase transition, get lath martensite tempering is to be obtained α-rich phase and a small amount of carbon, nickel austenite. 3.2 quenching (QT) with bipolar processing zone (IHT) quenching, 9Ni steel quenching temperature is generally 800 ~ 900 ℃, while holding it after sufficient time to fully austenitic, at 565 ~ 635 ℃ tempering, tempering time by 1.2min / mm computing, but at least more than 15min. Intercritical 9Ni steel processing is based on the quenching, tempering prior to (α + γ) duplex region processing is intended to enable the tissue distribution more diffuse, uniform. After quenching organization 9Ni low carbon steel lath martensite matrix organization after tempering get is tempered martensite and austenite part of the rotation. 9Ni steel after (α + γ) two-phase zone treatment, the impact toughness higher than -196 ℃ transfer of heat treatment of 0.5 to 1 times, even better than 1Cr18Ni8Ti stainless steel 1Cr18Ni8Ti strength is 2 times, resistance to temper embrittlement capabilities are greatly improved. In the prior three heat treatment process, by double normalizing (NNT) heat-treated steel 9Ni poor low temperature toughness, quenching and heat treatment, followed by low-temperature toughness (α + γ) two-phase region the best treatment. 4 9Ni 9Ni strength steel mechanical properties of steel extreme high and at low temperatures, further substantial increase (decrease in toughness). For heat-treated by QT 9Ni steel, bent at room temperature is stronger than about 0.85, and there is a higher work hardening tendency. Therefore, 9Ni steel manufacturing equipment, should be strictly controlled and groups forming process, to prevent cracks, especially surface cracks. 9Ni steel mechanical properties are shown in Table 2. Table 2 9Ni mechanical properties of steel mechanical properties 06Ni9DR (9% Ni) yield strength Rel (MPa) yield strength or σb 680-820 Rel (MPa) or σs thickness of 5 ~ 30mm Rel≥585; thickness> 30mm Rel≥575 Elongation A (%) or σ5 ≥18 cold bend test b = 2a 180 ° d = 3a Charpy impact strength of three average (J) single value (J) ≥70 experimental temperature (℃) -196 test shape 2mmV type I ≥100 Company perennial spot, complete specifications, inventory, price concessions, with a large gantry crane and truck fleet, 24 hours for your service, the company's goods sent to the country, welcomed the new and old customers to meet Fair