Low-temperature-resistant and corrosion-resistant welding material for LNG storage tank and preparation method thereof

Abstract

The application belongs to the field of metal material processing and specifically relates to a low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks and a preparation method thereof. The welding alloy material comprises a welding wire and a coating. The welding wire comprises the following powder raw materials in parts by weight: C: 0.30-0.45%, Si: 0.05-0.20%, Mn: 20.0-22.0%, Cr: 6.0-8.0%, Ni: 12.0-15.0%, Mo: 1.5-2.0%, B: 0.001-0.005%, Ti: 0.05-0.10%, Nb: 1.0-1.5%, V: 0.2-0.5%, Cu: 0.3-0.5%, RE: 0.05-0.15%, nanomaterial: 0.30-0.50%, S: <0.005%, P: <0.005%, and Fe: the balance. The welding wire raw material is treated by high-temperature vacuum melting-atomization powdering-wet mixing method blending-heat isostatic pressing, and is subjected to multi-pass drawing-annealing and solid solution treatment, and finally is subjected to pickling and coating preparation, so that the problem that the low-temperature impact resistance of deposited metal of the welding alloy material for LNG storage tanks in the prior art is poor, the corrosion resistance is poor, and the service life is affected can be effectively solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metal materials, and particularly relates to a low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks and a preparation method thereof. BACKGROUND

[0002] The working temperature of an LNG storage tank is 163 DEG C, and the low-temperature plasticity of the material is greatly required. The low-temperature material for the LNG storage tank mainly includes a nickel-containing alloy steel mainly composed of 9%Ni steel, an ultra-low-temperature austenitic stainless steel, and an ultra-low-temperature aluminum alloy. According to different occasions, the use of various materials is different, and the 9%Ni steel is most widely used. However, due to the fact that the price of nickel element continuously remains at a high level, the price of the nickel-based low-temperature steel is high, which continuously makes the cost of LNG storage and transportation equipment be high, and to some extent, becomes a resistance to the development of LNG clean energy.

[0003] The ultra-low-temperature high-manganese steel (22-28% Mn content) has the same physical and metallurgical characteristics as the 9Ni steel, and has the advantages of high performance (excellent crack resistance) and low cost (cost saving of 30-40%), and is the first choice of the competitive material for replacing the 9Ni steel as the steel for LNG storage tanks, and has an immeasurable application prospect, and has become a research hotspot in the world. In 2015, the high-manganese steel for LNG storage tanks developed by POSCO, Daewoo Shipbuilding & Marine Engineering Co., Ltd., and the five largest ship classification societies (ABS, BV, DNV GL, KR, and LR) has realized batch production.

[0004] On the other hand, in the application process of the LNG storage tank, the complexity of the stored gas, even if there is a trace amount of hydrogen gas, amino, hydrogen sulfide, etc., can also cause hydrogen embrittlement and corrosion of the storage tank. As described above, even if the content of the hydrogen sulfide gas is very low, as long as there is water, the metal material can suddenly produce sulfide stress cracking. The problems caused by hydrogen-induced corrosion (HIC) and sulfide stress corrosion (SSC) in the storage and transportation of natural gas resources and some chemical products are paid more and more attention, and the requirements for the corresponding materials (such as welding materials) are also higher and higher.

[0005] Therefore, it is of great significance to develop a solid welding wire with good ultra-low-temperature impact toughness, corrosion resistance, and matching with the ultra-low-temperature high-manganese steel, a welding joint with high strength, excellent welding process performance, and good weld formation. SUMMARY

[0006] The present application aims at the problem of poor low-temperature impact resistance and poor corrosion resistance of the deposited metal of the welding alloy material for the LNG storage tank in the prior art, and provides a new low-temperature-resistant and corrosion-resistant welding material for the LNG storage tank and a preparation method thereof. The new material is designed and optimized by formula, and can effectively solve the above problems. In order to achieve the above purpose, the technical scheme adopted by the present application to solve the technical problem is that:

[0007] The application provides a low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks, which comprises the following powder raw materials in parts by weight: C: 0.30-0.45%, Si: 0.05-0.20%, Mn: 20.0-22.0%, Cr: 6.0-8.0%, Ni: 12.0-15.0%, Mo: 1.5-2.0%, B: 0.001-0.005%, Ti: 0.05-0.10%, Nb: 1.0-1.5%, V: 0.2-0.5%, Cu: 0.3-0.5%, RE: 0.05-0.15%, nanomaterial: 0.30-0.50%, S: <0.005%, P: <0.005%, and Fe: balance.

[0008] Further, the ratio of the amount of Mn to Cr is 2.75-3.35.

[0009] Further, the RE is one or more of Y, La and Ce.

[0010] The application further provides a preparation method of the low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks.

[0011] S1: oxidation treatment: performing surface oxidation treatment on the nanomaterial to obtain an oxidized nanomaterial;

[0012] S2: surface modification treatment: performing ball milling treatment on the oxidized nanomaterial and RE and Cr to obtain a modified nanomaterial;

[0013] S3: raw material proportioning: under the protection of argon, preparing raw metal powder except the modified nanomaterial;

[0014] S4: high-temperature vacuum smelting: performing high-temperature vacuum smelting on the prepared metal powder to obtain an alloy melt;

[0015] S5: atomization powdering: performing argon atomization treatment on the alloy melt, and screening to obtain spherical atomized alloy powder;

[0016] S6: wet mixing method blending: adding the spherical atomized alloy powder and the modified nanomaterial into ethanol, performing ultrasonic treatment to obtain an ethanol suspension, and performing drying treatment to obtain a mixed powder;

[0017] S7: hot isostatic pressing treatment: placing the mixed powder in a stainless steel sleeve with a certain space reserved, performing degassing treatment, and then placing the mixed powder in a hot isostatic pressing machine to sinter into a rod blank;

[0018] S8: forging and rolling: performing forging and rolling on the rod blank to prepare an alloy rod;

[0019] S9: solid solution treatment;

[0020] S10: surface treatment; i.e.

[0021] The alloy wire is subjected to acid pickling coating to obtain the target product.

[0022] Further, the nanomaterials include two-dimensional nanomaterials.

[0023] Further, the two-dimensional nanomaterials are graphene.

[0024] Another object of the present application is to provide a welding method of the low-temperature and corrosion-resistant welding material for LNG storage tanks, which adopts argon protection, the argon flow rate is 15-20 L / min, the welding current is 300-400 A, the voltage is 28-32 V, and post-welding heat treatment is performed.

[0025] Further, the post-welding heat treatment is heat treatment at 600-620 ℃ for 2.0-2.5 h.

[0026] The present application has the following beneficial effects:

[0027] (1) The present application provides a low-temperature and corrosion-resistant welding material for LNG storage tanks, in which Fe is used as the base body in the welding wire structure, Mn promotes the formation of full austenite welds, and ensures the low-temperature comprehensive mechanical properties of the weld metal; Cr can strengthen the austenite grain boundary and improve the corrosion resistance; Ni is a strong austenite-forming element, which can effectively improve the low-temperature toughness of the weld metal; at the same time, it has excellent corrosion resistance; Mo is a solid solution strengthening element, which can refine the grains and improve the strength of the weld metal. At the same time, Mn, C and Ni are all austenite-forming elements, which work together when the weld metal solidifies in the molten pool, and the initial phase is austenite, which remains until room temperature, forming an austenite-organized weld metal, which has excellent ultra-low-temperature toughness.

[0028] (2) The present application provides a low-temperature and corrosion-resistant welding material for LNG storage tanks, in which a certain amount of Ti, V and Cu elements are added to the welding wire alloy. On the one hand, Ti can improve the weldability of the alloy, and has strong affinity with oxygen, which can be used as a deoxidizing element to protect the weld from oxidation, thereby effectively inhibiting the formation of CO and N2 pores, which is beneficial to the formation of the weld; on the other hand, Ti can also reduce the grain size of the weld metal and improve the comprehensive mechanical properties; V precipitates have stability and hydrogen trapping ability, and the ionic bond formed by the carbide of V and hydrogen is the strongest, which has hydrogen embrittlement resistance; Cu can improve the corrosion resistance of the weld, and the affinity of copper with oxygen is smaller than that of iron, so most of it can be transferred to the weld during welding, forming a protective film layer to prevent the corrosion reaction of ammonia, hydrogen sulfide, etc., thereby improving the corrosion resistance.

[0029] (3) The application provides a low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks, wherein a certain amount of nanomaterial is added to the alloy, and the nanomaterial is subjected to ball milling modification treatment together with RE and Cr. Firstly, RE has a wetting effect, can reduce the interfacial tension, makes the new phase and the matrix combine more closely, is helpful to the better spreading and combination of the weld filler metal, and improves the mechanical properties of the weld; Cr can form a dense Cr2O3 protective layer on the surface, has oxidation resistance and corrosion resistance; secondly, the two-dimensional nanomaterial has a super large specific surface area, effectively prevents the grain growth in heat treatment, has the effect of fine-grain strengthening; meanwhile, can increase the lattice distortion energy of the dislocation affected zone, increases the sliding resistance, and improves the low-temperature resistance; in addition, the two-dimensional planar structure can effectively block the corrosion factors, and further improves the corrosion resistance; thirdly, the wetting property of the rare earth provides excellent compatibility between the nanomaterial and the metal; meanwhile, the rare earth is enriched at the phase interface, and further improves the corrosion resistance of the welding material; fourthly, due to the high specific surface area of the nanomaterial, the Cr modified on the surface has excellent synergistic effect, has high corrosion resistance while ensuring the low-temperature toughness. DETAILED DESCRIPTION

[0030] The application will be described in detail below in combination with examples. However, it should be understood that the following examples are only illustrative of the embodiments of the application, and are not a limitation on the scope of the application.

[0031] The purpose of the application is to develop a low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks, so as to solve the problems of poor low-temperature impact resistance and poor corrosion resistance of the deposited metal of the existing welding alloy material for LNG storage tanks. The idea is as follows: Mn in the deposited metal can ensure the low-temperature comprehensive mechanical properties of the weld metal, including low-temperature toughness; Cr is a solid solution strengthening element, forms a dense Cr2O3 protective layer, and has corrosion resistance, but Cr>8% will reduce the low-temperature toughness; a low content is insufficient to play the corrosion resistance; that is, Mn and Cr have different focuses in low-temperature toughness and corrosion resistance, but there is a certain antagonism; considering that the nanomaterial has a high specific surface area, has a synergistic effect on the material performance; meanwhile, the two-dimensional nanomaterial also has the functions of improving the mechanical properties, shielding corrosion factors, and the like; the surface of the two-dimensional nanomaterial is modified by Cr, which can improve the corrosion resistance under the premise of adding insufficient amount of Cr; meanwhile, the surface is modified by the rare earth metal, which improves the wetting property and compatibility between the metals; the two-dimensional nanomaterial has the mechanisms of refining the grains, increasing the lattice distortion energy of the dislocation affected zone, and bearing the load, and the like, to improve various performances; and through the formula design, the addition of trace elements such as Ti, V and Cu, and the cooperation with the preparation process and the welding process, a new type of low-temperature-resistant and corrosion-resistant welding material and a deposited metal with excellent performance can be prepared. The embodiments of the application are as follows:

[0032] The embodiment of the present application provides a low-temperature-resistant and corrosion-resistant welding material for LNG storage tank, which comprises the following powder raw materials in parts by weight: C: 0.30-0.45%, Si: 0.05-0.20%, Mn: 20.0-22.0%, Cr: 6.0-8.0%, Ni: 12.0-15.0%, Mo: 1.5-2.0%, B: 0.001-0.005%, Ti: 0.05-0.10%, Nb: 1.0-1.5%, V: 0.2-0.5%, Cu: 0.3-0.5%, RE: 0.05-0.15%, nanomaterial: 0.30-0.50%, S: <0.005%, P: <0.005%, and Fe: balance.

[0033] The content ratio of Mn and Cr is 2.75-3.35.

[0034] Mn is a strong austenite-forming element, promotes the formation of full austenite weld, ensures the low-temperature comprehensive mechanical properties of the weld metal, including strength, plasticity and low-temperature toughness, and the Mn content in the application is 21-25%.

[0035] Cr is a solid solution strengthening element, and can also strengthen the austenite grain boundary, and forms a dense Cr2O3 protective layer on the surface of the base material, which has the effects of oxidation resistance and corrosion resistance; but when Cr is greater than 8%, the low-temperature toughness is reduced and the weld forming is deteriorated, and the Cr content in the application is 6.0-8.0%.

[0036] Meanwhile, considering the performance supplement effect of Mn and Cr, in order to ensure the best comprehensive performance, the content ratio of Mn and Cr is 2.75-3.35, so that the welding material has excellent low-temperature effect and certain corrosion resistance.

[0037] The above-mentioned RE is one or more of Y, La or Ce.

[0038] RE has good wettability, can improve the mechanical strength of the weld, can purify the grain boundary, reduce the segregation of impurity elements at the grain boundary, and improve the low-temperature toughness and corrosion resistance of the welding material.

[0039] In addition, other important components and effects in the embodiment of the present application are as follows:

[0040] Si acts as a deoxidizer, can improve the purity of the weld, reduce defects, improve the strength of the weld, and reduce the tendency of solidification cracks; but too high content can cause the weld metal to become brittle, reduce plasticity and toughness. Therefore, the Si content is controlled to be 0.05-0.20% in the present application.

[0041] Ni in the alloy also mainly plays a solid solution strengthening effect, and the substitution of Ni element can reduce the cost while Fe can also make the stacking sequence of the gamma matrix decrease, which has a positive effect on the improvement of yield strength. Therefore, the Fe content is controlled at 7.0-10.0% in the application.

[0042] Ni is a strong austenite forming element, which can effectively improve the low-temperature toughness and corrosion resistance of the weld metal, and also can improve the oxidation resistance of the material, offset the problems of weld structure coarsening and toughness decrease caused by the addition of Cr; but the price is expensive, and the content is too high, which will significantly increase the cost of the material, and the Ni content is controlled at 12.0-15.0% in the application.

[0043] Mo is a solid solution strengthening element, which can improve the weld strength and improve the corrosion resistance of the alloy, especially in the case of complex action with Cr, the pitting resistance is more excellent. Therefore, the Mo content is controlled at 1.5-2.0% in the application.

[0044] The addition of trace B element strengthens the grain boundary and improves the endurance strength of the weld metal, and the trace addition will not increase the sensitivity of welding cracks.

[0045] Ti is a strong deoxidizing element, which plays a deoxidizing role in the welding process, and Ti can also reduce the grain size of the weld metal and improve the comprehensive mechanical properties, and the Ti content range is 0.05-0.10% in the application.

[0046] Nb can increase the lattice distortion and lattice atomic bond attraction of the solid solution, so that the matrix is strengthened, and the solid solution strengthening effect is more significant; at the same time, it is also a strong carbide forming element, which can form MC, M6C or M2C type carbide, which has a significant second phase strengthening effect on the weld metal and improves the mechanical properties. Therefore, the Nb content is controlled at 1.0-1.5% in the application.

[0047] V can further ensure the yield strength and tensile strength of the deposited metal, and ensure the low-temperature toughness of the deposited metal; and the ionic bond formed by the carbide of V and hydrogen is the strongest, which has the performance of hydrogen embrittlement resistance, and has excellent storage effect on trace hydrogen in LNG. Therefore, the V content is controlled at 0.2-0.5% in the application.

[0048] Cu is an austenite forming element, which can improve the mechanical properties of the weld; at the same time, the affinity of copper and oxygen is smaller than that of iron, and most of it can be transferred to the weld during welding to form a protective film layer, which prevents the corrosion reaction of ammonia, hydrogen sulfide and other corrosion reactions, and improves the corrosion resistance. Therefore, the Cu content is controlled at 0.3-0.5% in the application.

[0049] Nanometer material has high specific surface area, and has significant synergistic effect after being modified with metal surface; and the material has low temperature resistance and corrosion resistance.

[0050] Fe is the main component and mainly plays a solid solution strengthening role in the alloy, and replacing the Ni element can reduce the cost.

[0051] Another purpose of the embodiment of the present application is to provide a preparation method of the low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks, comprising the following steps:

[0052] S1: oxidation treatment; that is

[0053] The nanomaterial is added to a mixed solution of concentrated nitric acid and concentrated sulfuric acid, ultrasonically dispersed at room temperature for 4-8h, heated to 60-80℃, refluxed for 1-4h, and then centrifuged to remove most of the acid, filtered, washed with deionized water until neutral, and placed in a vacuum dryer at 60℃ for 12h to obtain the oxidized nanomaterial.

[0054] The total amount of the nanomaterial is 1g, the amount of concentrated nitric acid is 30mL, and the amount of concentrated sulfuric acid is 90mL;

[0055] The nanomaterial includes a two-dimensional nanomaterial; it can also be a one-dimensional nanomaterial;

[0056] The amount ratio of the two-dimensional nanomaterial to the one-dimensional nanomaterial is 1.0g:0-0.3g;

[0057] The two-dimensional nanomaterial is graphene or other two-dimensional nanomaterials that can be oxidized by mixed acid;

[0058] The thickness of the graphene is 3-10nm, and the flake diameter is 5-10μm; and in the following embodiments and comparative examples of the present application, the graphene has a product number of 100078 and is purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0059] The one-dimensional nanomaterial is a carbon nanotube or a carbon nanofiber; and preferably a carbon nanotube;

[0060] The average tube diameter of the carbon nanotube is 10-30nm, and the aspect ratio is >500; and in the following embodiments and comparative examples of the present application, the carbon nanotube has a product number of CT-M-001 and is purchased from Jiangsu Chaocan Xianfeng Technology Co., Ltd.

[0061] S2: surface modification treatment; that is

[0062] The oxidized nanomaterial is added to anhydrous ethanol A and ultrasonically shaken for 20min to obtain a dispersion liquid; the dispersion liquid, RE, Cr, and anhydrous ethanol B are added to a ball mill for ball milling treatment for 15-24h, filtered, and the insoluble matter is placed in a vacuum dryer at 60℃ for 12h to obtain the modified nanomaterial.

[0063] The ratio of the above-mentioned oxidized nanomaterial, anhydrous ethanol A, RE, anhydrous ethanol B is 0.30-0.50 g:20 mL:0.05-0.15 g:6.0-8.0 g:30 mL.

[0064] The ball milling treatment rotation speed is 200-300 r / min, and the ball-to-material mass ratio is 8-10:1.

[0065] The average particle size of the above-mentioned RE and Cr is 30 μm.

[0066] S3: Raw material ratio: under argon protection, prepare the original metal powder except for the modified nanomaterial;

[0067] The average particle size of the above-mentioned original metal powder is 50-100 μm.

[0068] S4: High-temperature vacuum melting: high-temperature vacuum melting of the prepared metal powder to obtain an alloy melt;

[0069] The vacuum degree of the above-mentioned vacuum melting is 5×10 3 -8×10 3Pa，熔炼温度为1420-1600℃。

[0070] S5: Atomization powdering: the alloy melt is treated by argon atomization method, and after screening, spherical atomized alloy powder is obtained;

[0071] The process parameters of the above-mentioned argon atomization method are: atomization temperature 1680-1720℃, atomization pressure 0.3 bar, inlet flow rate 45-55 mL / min, and 99.99% high-purity Ar.

[0072] S6: Wet mixing method blending: the spherical atomized alloy powder and the modified nanomaterial are added to ethanol, and after magnetic stirring at 1000 r / min for 3 h, ultrasonic treatment at 50 KHz for 2 h is performed to obtain an ethanol suspension; filtration, taking the insoluble substance, and placing it in a 80℃ drying box for drying treatment for 2 h to obtain a mixed powder.

[0073] S7: Hot isostatic pressing treatment: the mixed powder is placed in a stainless steel sleeve with a certain space reserved, degassed, and then sintered into a rod blank in a hot isostatic pressing machine;

[0074] The degassing process is that the furnace temperature is kept at 660-700℃, the vacuum degree is <0.1 Pa, and the keeping time is 6-8 h; the sintering process is that the heating rate is 25℃ / min, the temperature is raised to 1220-1280℃, then a gas pressure of 120-180 MPa is applied to the surface, and the constant pressure and temperature are kept for 4-6 h, and the furnace is cooled to obtain a cylindrical powder sintered rod blank.

[0075] S8: Forging and rolling: the rod blank is forged and rolled to prepare an alloy rod, and annealing-drawing treatment is performed.

[0076] The forging process is to forge the alloy blank at 1080-1130℃, and the forging ratio is 3-4.

[0077] The rolling process is to heat the alloy blank to 1180-1220℃ for 0.5-1.5h, and then hot-rolled to Φ7.0-8.0mm alloy wire rod at 1020-1080℃.

[0078] A lubricant is added before drawing, and the alloy wire rod is drawn for 6-8 passes to obtain Φ1.2mm alloy wire rod.

[0079] The annealing-drawing process of the present application has no special requirements, and the annealing-drawing process known in the art can be used.

[0080] S9: solution treatment;

[0081] The solution treatment is a multi-step grading treatment; specifically, the alloy is heated to 900-1000℃ in a nitrogen environment, and held for 2-3h, then heated to 1000-1100℃, and held for 2-3h, and then rapidly water quenched to obtain the solution-treated alloy.

[0082] S10: surface treatment; that is,

[0083] The alloy wire rod is pickled; coated; specifically, and unless otherwise specified, the pickling in the following examples and comparative examples of the present application is to pickle the alloy wire rod after heat treatment, first pickled in a mixed pickling solution containing 100g / L nitric acid and 20g / L hydrofluoric acid, the temperature is controlled to ≤50°C, and the pickling time is 10min; and finally the residual acid on the surface is cleaned;

[0084] The coating is to coat a water-soluble coating agent on the surface of the pickled alloy wire rod, and the coated alloy wire rod is naturally air-dried.

[0085] Another purpose of the embodiment of the present application is to provide a welding method for the low-temperature corrosion-resistant welding material for LNG storage tanks, which uses argon protection, the argon flow rate is 15-20L / min; the welding current is 300-400A, the voltage is 28-32V; and post-weld heat treatment is performed.

[0086] The post-weld heat treatment is to heat treat the alloy wire rod at 600-620℃ for 2.0-2.5h.

[0087] In order to further understand the present application, the low-temperature corrosion-resistant welding material for LNG storage tanks provided by the present application will be described in detail below in conjunction with specific examples, and the protection scope of the present application is not limited by the following examples.

[0088] Example 1

[0089] The embodiment provides a low-temperature-resistant and corrosion-resistant welding material for an LNG storage tank, which comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 21.0%, Cr: 7.0%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0090] The RE is Y.

[0091] Another purpose of the embodiment is to provide a preparation method of the low-temperature-resistant and corrosion-resistant welding material for the LNG storage tank, which comprises the following steps:

[0092] S1: oxidation treatment, namely

[0093] The nanomaterial is added into a mixed solution of concentrated nitric acid and concentrated sulfuric acid, ultrasonic dispersion is carried out at room temperature for 6h, then the temperature is increased to 70 DEG C, reflux is carried out for 2h, most of the acid is removed by centrifugation, then filtration is carried out, the insoluble substance is washed to neutral with deionized water, and vacuum drying is carried out at 60 DEG C for 12h, so that the oxidized nanomaterial is obtained.

[0094] The total amount of the nanomaterial and the amount of the concentrated nitric acid and the concentrated sulfuric acid are 1g: 30mL: 90mL.

[0095] The amount of the nanomaterial and the amount of the concentrated nitric acid and the concentrated sulfuric acid are 1g: 30mL: 90mL.

[0096] S2: surface modification treatment, namely

[0097] The oxidized nanomaterial is added into anhydrous ethanol A and ultrasonic oscillation is carried out for 20min, so that a dispersion liquid is obtained; the dispersion liquid, RE, Cr and anhydrous ethanol B are added into a ball mill for ball milling treatment for 20h, then filtration is carried out, the insoluble substance is taken out, and vacuum drying is carried out at 60 DEG C for 12h, so that the modified nanomaterial is obtained.

[0098] The amount of the oxidized nanomaterial, the anhydrous ethanol A, the RE, the anhydrous ethanol B, the argon and the concentrated nitric acid is 0.40g: 20mL: 0.10g: 7.0g: 30mL: 0.2g: 0.2mL.

[0099] The ball milling treatment rotation speed is 271r / min, and the ball-to-material mass ratio is 9:1.

[0100] S3: raw material proportioning: under the protection of argon, the original metal powder except the modified nanomaterial is prepared.

[0101] S4: high-temperature vacuum smelting: the prepared metal powder is subjected to high-temperature vacuum smelting, so that an alloy melt is obtained;

[0102] The vacuum degree of the vacuum melting is 6*10 3 Pa, and the melting temperature is 1500℃.

[0103] S5: atomization and powdering: the alloy melt is treated by argon atomization method, and spherical atomized alloy powder is obtained after screening;

[0104] The process parameters of the argon atomization method are as follows: atomization temperature 1700℃, atomization pressure 0.3 bar, flow rate 50 mL / min, and high-purity Ar 99.99%.

[0105] S6: blending by wet mixing method: the spherical atomized alloy powder and modified nanomaterial are added into ethanol, and after magnetic stirring at 1000 r / min for 3 h, ultrasonic treatment is performed at 50 KHz for 2 h to obtain an ethanol suspension; filtration is performed, and the insoluble substance is placed in a drying box at 80℃ for drying treatment for 2 h to obtain a mixed powder.

[0106] S7: hot isostatic pressing treatment: the mixed powder is placed in a stainless steel sleeve with a certain space reserved, degassing treatment is performed, and then the mixed powder is placed in a hot isostatic pressing machine to sinter a rod blank;

[0107] The degassing treatment process is as follows: the furnace temperature is kept at 680℃, the vacuum degree is less than 0.1 Pa, and the keeping time is 7 h; the sintering process is as follows: the heating rate is 25℃ / min, the temperature is raised to 1250℃, then a gas pressure of 165 MPa is applied to the surface, and the temperature is kept constant for 5 h, and the rod blank is cooled in the furnace to obtain a cylindrical powder sintered rod blank.

[0108] S8: forging and rolling: the rod blank is forged and rolled to prepare an alloy rod, and annealing-drawing treatment is performed;

[0109] The forging process is as follows: the alloy blank is forged at 1100℃, and the forging ratio is 3.5.

[0110] The rolling process is as follows: the temperature is kept at 1200℃ for 1.0 h, and the alloy rod is hot-rolled into a Φ7.5 mm alloy rod at 1050℃.

[0111] A lubricant is added before drawing, 6-8 drawing passes are performed, and a Φ1.2 mm alloy wire is obtained.

[0112] S9: solid solution treatment;

[0113] The solid solution treatment is a multi-step grading treatment; specifically, the alloy is heated to 950℃ in a nitrogen environment, kept for 2.5 h, continuously heated to 1050℃, kept for 2.5 h, and rapidly water quenched to obtain a solid solution alloy.

[0114] S10: the target product is obtained after surface treatment.

[0115] Another purpose of the embodiment is to provide a welding method of the low-temperature and corrosion-resistant welding material for LNG storage tanks, which adopts argon protection, the argon flow is 18L / min, the welding current is 350A, the voltage is 30V, and post-welding heat treatment is performed.

[0116] The post-welding heat treatment is heat treatment at 610℃ for 2.0h.

[0117] Embodiment 2

[0118] The embodiment provides a low-temperature and corrosion-resistant welding material for LNG storage tanks, which comprises the following powder raw materials in parts by weight: C: 0.30%, Si: 0.20%, Mn: 20.0%, Cr: 6.0%, Ni: 15.0%, Mo: 2.0%, B: 0.005%, Ti: 0.05%, Nb: 1.0%, V: 0.5%, Cu: 0.5%, RE: 0.15%, nanomaterial: 0.50%, S: 0.002%, P: 0.001%, and Fe: the balance.

[0119] The RE is Y.

[0120] Another purpose of the embodiment is to provide a preparation method of the low-temperature and corrosion-resistant welding material for LNG storage tanks, which comprises the following steps:

[0121] S1: oxidation treatment, that is,

[0122] The nanomaterial is added into a mixed solution of concentrated nitric acid and concentrated sulfuric acid, ultrasonic dispersion is performed at room temperature for 4h, then the temperature is increased to 60℃, reflux is performed for 4h, most of the acid is removed by centrifugation, filtration is performed, the insoluble substance is washed to neutral with deionized water, and vacuum drying is performed at 60℃ for 12h, so that the oxidized nanomaterial is obtained.

[0123] The total amount of the nanomaterial and the amount of the concentrated nitric acid and the concentrated sulfuric acid are in a ratio of 1g: 30mL: 90mL.

[0124] The amount of the nanomaterial and the amount of the graphene and the carbon nanotube are in a ratio of 1.0g: 0.2g.

[0125] S2: surface modification treatment, that is,

[0126] The oxidized nanomaterial is added into anhydrous ethanol A and ultrasonic oscillation is performed for 20min, so that a dispersion liquid is obtained; the dispersion liquid, RE, Cr and anhydrous ethanol B are added into a ball mill for ball milling treatment for 15h, then filtration is performed, the insoluble substance is taken, and vacuum drying is performed at 60℃ for 12h, so that the modified nanomaterial is obtained.

[0127] The amount of the oxidized nanomaterial, the anhydrous ethanol A, the RE, the anhydrous ethanol B is in a ratio of 0.50g: 20mL: 0.15g: 6.0g: 30mL.

[0128] The ball milling treatment rotation speed is 295 r / min, and the ball-to-material mass ratio is 8:1.

[0129] S3: Raw material ratio: Under argon protection, prepare the original metal powder except for the modified nanomaterial.

[0130] S4: High-temperature vacuum melting: Perform high-temperature vacuum melting on the prepared metal powder to obtain an alloy melt;

[0131] The vacuum degree of the above vacuum melting is 8×10 3 Pa, and the melting temperature is 1420°C.

[0132] S5: Atomization powdering: Process the alloy melt by argon atomization to obtain spherical atomized alloy powder after screening;

[0133] The process parameters of the above argon atomization are as follows: atomization temperature 1720°C, atomization pressure 0.3 bar, flow rate 45 mL / min, and 99.99% high-purity Ar.

[0134] S6: Wet mixing method blending: Add the spherical atomized alloy powder and the modified nanomaterial into ethanol, magnetically stir at 1000 r / min for 3 h, and then perform ultrasonic treatment at 50 KHz for 2 h to obtain an ethanol suspension; filter, take the insoluble substance, and place it in a 80°C drying box for drying treatment for 2 h to obtain a mixed powder.

[0135] S7: Hot isostatic pressing treatment: Place the mixed powder in a stainless steel sleeve with a certain space reserved, perform degassing treatment, and then place it in a hot isostatic pressing machine to sinter into a rod blank;

[0136] The degassing treatment process is to keep the furnace temperature at 700°C, the vacuum degree is <0.1 Pa, and the holding time is 6 h; the sintering process is to heat at a rate of 25°C / min to 1280°C, then apply a gas pressure of 120 MPa to the surface, and keep the pressure and temperature constant for 4 h, and then cool down with the furnace to obtain a cylindrical powder sintered rod blank.

[0137] S8: Forging and rolling: Perform forging and rolling on the rod blank to prepare an alloy rod, and perform annealing-drawing treatment;

[0138] The forging process is to open die forging into an alloy blank at 1130°C, and the forging ratio is 3.

[0139] The rolling process is to heat at 1220°C for 0.5 h, and then hot roll into a Φ8.0 mm alloy rod at 1080°C.

[0140] Add a lubricant before drawing, and perform 6-8 pass drawing to obtain a Φ1.2 mm alloy wire.

[0141] S9: solid solution treatment;

[0142] The solid solution treatment is a multi-step grading treatment; specifically, heating to 900 DEG C under a nitrogen environment, holding for 3h, continuously heating to 1000 DEG C, holding for 3h, and rapidly water quenching to obtain the solid solution alloy.

[0143] S10: the target product is obtained after the surface treatment.

[0144] Another purpose of the embodiment is to provide a welding method of the low-temperature and corrosion-resistant welding material for LNG storage tanks, which adopts argon protection, the argon flow is 20 L / min, the welding current is 400 A, the voltage is 28 V, and post-welding heat treatment is performed.

[0145] The post-welding heat treatment is heat treatment at 600 DEG C for 2.5h.

[0146] Embodiment 3

[0147] The embodiment provides a low-temperature and corrosion-resistant welding material for LNG storage tanks, which comprises the following powder raw materials in parts by weight: C: 0.45%, Si: 0.05%, Mn: 22.0%, Cr: 8.0%, Ni: 12.0%, Mo: 1.5%, B: 0.001%, Ti: 0.10%, Nb: 1.5%, V: 0.2%, Cu: 0.3%, RE: 0.05%, nanomaterial: 0.30%, S: 0.002%, P: 0.001%, and Fe: the balance.

[0148] The RE is Y.

[0149] Another purpose of the embodiment is to provide a preparation method of the low-temperature and corrosion-resistant welding material for LNG storage tanks, which comprises the following steps:

[0150] S1: oxidation treatment; that is

[0151] The nanomaterial is added into a mixed solution of concentrated nitric acid and concentrated sulfuric acid, ultrasonic dispersion is performed at room temperature for 8h, then the temperature is increased to 80 DEG C, reflux is performed for 1h, most of the acid is removed by centrifugation, filtration is performed, the insoluble substance is washed to neutral with deionized water, and vacuum drying is performed at 60 DEG C for 12h to obtain the oxidized nanomaterial.

[0152] The total amount of the nanomaterial and the amount of the concentrated nitric acid and the concentrated sulfuric acid are 1g: 30mL: 90mL.

[0153] The amount ratio of the graphene and the carbon nanotube in the nanomaterial is 1.0g: 0.2g.

[0154] S2: surface modification treatment; that is

[0155] The oxidized nanomaterial is added into anhydrous ethanol A and ultrasonically shaken for 20 min to obtain a dispersion; the dispersion, RE, Cr, anhydrous ethanol B are added into a ball mill for ball milling treatment for 24 h, then filtered, and the insoluble substance is taken out and placed in a vacuum drying oven at 60℃ for 12 h to obtain the modified nanomaterial.

[0156] The above-mentioned oxidized nanomaterial, anhydrous ethanol A, RE, anhydrous ethanol B are in a ratio of 0.30 g:20 mL:0.05 g:8.0 g:30 mL.

[0157] The above-mentioned ball milling treatment is at a rotation speed of 211 r / min, and the ball-to-material mass ratio is 10:1.

[0158] S3: Raw material ratio: under argon protection, the original metal powder except the modified nanomaterial is prepared.

[0159] S4: High-temperature vacuum melting: the prepared metal powder is subjected to high-temperature vacuum melting to obtain an alloy melt;

[0160] The above-mentioned vacuum melting is at a vacuum degree of 5×10 3 Pa, and the melting temperature is 1600℃.

[0161] S5: Atomization powdering: the alloy melt is subjected to argon atomization treatment, and after screening, spherical atomized alloy powder is obtained;

[0162] The above-mentioned argon atomization treatment process parameters are: atomization temperature 1680℃, atomization pressure 0.3 bar, inlet flow rate 55 mL / min, and 99.99% high-purity Ar.

[0163] S6: Wet mixing method blending: the spherical atomized alloy powder and the modified nanomaterial are added into ethanol, and after magnetic stirring at 1000 r / min for 3 h, ultrasonic treatment at 50 KHz for 2 h is performed to obtain an ethanol suspension; the suspension is filtered, and the insoluble substance is taken out and placed in an 80℃ drying oven for drying treatment for 2 h to obtain a mixed powder.

[0164] S7: Hot isostatic pressing treatment: the mixed powder is placed in a stainless steel sleeve with a certain space reserved, degassed, and then placed in a hot isostatic pressing machine to sinter into a rod blank;

[0165] The above-mentioned degassing treatment process is to keep the furnace temperature at 660℃, the vacuum degree is <0.1 Pa, and the holding time is 8 h; the above-mentioned sintering process is to heat at a rate of 25℃ / min to 1220℃, then apply a gas pressure of 180 MPa to the surface, and keep the pressure and temperature constant for 6 h, and then cool down with the furnace to obtain a cylindrical powder sintered rod blank.

[0166] S8: Forging and rolling: the rod blank is subjected to forging and rolling to prepare an alloy rod, and then subjected to annealing-drawing treatment.

[0167] The forging process is as follows: 1080℃, open forging into an alloy blank, forging ratio 4;

[0168] The rolling process is as follows: 1180℃, holding for 1.5h, 1020℃, hot rolling into Φ7.0mm alloy wire rod.

[0169] Before drawing, add lubricant, carry out 6-8 pass drawing process, obtain Φ1.2mm alloy wire.

[0170] S9: solution treatment;

[0171] The solution treatment is a multi-step grading treatment; specifically, under nitrogen environment, heat to 1000℃, hold for 2h, continue to heat to 1100℃, hold for 2h, rapid water quenching to obtain the solution state alloy.

[0172] S10: after surface treatment, the target product is obtained.

[0173] Another purpose of the embodiment is to provide a welding method of the low-temperature and corrosion-resistant welding material for LNG storage tanks, which adopts argon protection, the argon flow is 15L / min; the welding current is 300A, the voltage is 32V; and post-welding heat treatment is carried out.

[0174] The post-welding heat treatment is 620℃, heat treatment for 2.0h.

[0175] Example 4

[0176] The same as example 1, except that:

[0177] A low-temperature and corrosion-resistant welding material for LNG storage tanks, comprising the following weight fractions of powder raw materials: C: 0.38%, Si: 0.12%, Mn: 20.0%, Cr: 6.6%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, Fe balance.

[0178] Example 5

[0179] The same as example 1, except that:

[0180] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 22.0%, Cr: 7.3%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0181] Example 6

[0182] Other than Example 1, except that:

[0183] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 22.0%, Cr: 7.3%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0184] Preferably, RE is Ce.

[0185] Example 7

[0186] Other than Example 1, except that:

[0187] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 22.0%, Cr: 7.3%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0188] Preferably, RE is Y mixed with La at a mass ratio of 3:1.

[0189] Example 8

[0190] Other than Example 1, except that:

[0191] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 22.0%, Cr: 7.3%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0192] Preferably, the nanomaterial is graphene and carbon nanotube at a ratio of 1.0g:0.3g.

[0193] Example 9

[0194] Other than Example 1, except that:

[0195] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 22.0%, Cr: 7.3%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0196] Preferably, the nanomaterial is graphene and carbon nanotube at a ratio of 1.0g:0g; i.e., no carbon nanotube is added.

[0197] The following comparative examples are compared with Example 1:

[0198] Comparative Example 1

[0199] Other than Example 1, except that:

[0200] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 21.0%, Cr: 8.0%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0201] Comparative Example 2

[0202] Other than Example 1, the difference is that:

[0203] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 21.0%, Cr: 8.0%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0204] V is not added.

[0205] Comparative Example 3

[0206] Other than Example 1, the difference is that:

[0207] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 21.0%, Cr: 8.0%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0208] Cu is not added.

[0209] Comparative Example 4

[0210] Other than Example 1, the difference is that:

[0211] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 21.0%, Cr: 8.0%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0212] RE is not added.

[0213] Comparative Example 5

[0214] Other than Example 1, the difference is that:

[0215] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 21.0%, Cr: 8.0%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0216] Nanomaterial is not added.

[0217] Comparative Example 6

[0218] Other than Example 1, the difference is that:

[0219] A low-temperature corrosion-resistant welding material for LNG storage tanks comprises the following powder raw materials in parts by weight: C: 0.38%, Si: 0.12%, Mn: 21.0%, Cr: 8.0%, Ni: 13.5%, Mo: 1.8%, B: 0.003%, Ti: 0.08%, Nb: 1.2%, V: 0.36%, Cu: 0.4%, RE: 0.10%, nanomaterial: 0.40%, S: 0.002%, P: 0.001%, and Fe: balance.

[0220] Preferably, the ratio of the amount of graphene to carbon nanotubes in the nanomaterial is 0g:0.2g; that is, graphene is added.

[0221] Comparative Example 7

[0222] Other than Example 1, except that:

[0223] A preparation method of a low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks,

[0224] No S1 and S2 operations are performed; that is, no modification treatment of the nanomaterial is performed.

[0225] Comparative Example 8

[0226] Other than Example 1, except that:

[0227] A welding method of a low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks,

[0228] No post-welding treatment is performed.

[0229] The welding material and the welding method obtained in the examples and the comparative examples are used to weld high-manganese austenitic steel, and the chemical components are: C: ≤0.40-0.50%, Si: 0.10-0.20%, Mn: 20-28%, N: 0.01-0.08%, P≤0.005%, S≤0.003%; the size is 400mm×300mm×20mm, the groove angle is 45°, the distance between the groove bottom is 20mm, the bottom is placed with a 400mm×60mm×10mm backing plate, a 3mm isolation layer is built up on the groove, and tungsten inert gas welding is performed.

[0230] The physical properties of the deposited metal of the low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks prepared in the examples and the comparative examples are measured respectively, and the results are shown in Table 1.

[0231] Table 1: Physical test performance of each example

[0232]

[0233] From Examples 1-9, it can be observed that the low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks of the present application has excellent mechanical properties, low-temperature resistance and corrosion resistance.

[0234] From Examples 1 and Comparative Examples 1-6, it can be observed that the appropriate Mn, Cr ratio and the addition of Cr content in the low-temperature-resistant and corrosion-resistant welding material for LNG storage tanks of the present application can significantly improve the low-temperature performance; V and Cu have a positive effect on corrosion resistance, in addition, Cu also has a positive effect on improving mechanical properties and low-temperature performance; RE has a positive effect on weld integrity, which can improve mechanical properties, low-temperature performance and corrosion resistance; nanomaterials, especially two-dimensional structure nanomaterials, have an important influence on improving corrosion resistance and low-temperature toughness;

[0235] From the comparison of the embodiment 1 and the comparative examples 7-8, it can be observed that in the preparation method of the low-temperature corrosion-resistant welding material for LNG storage tank, the RE, Cr and two-dimensional nanomaterials are effectively modified, which can significantly improve various performances; the post-weld heat treatment plays an important role in releasing stress, refining grain boundaries and improving performance.

[0236] In summary, the low-temperature corrosion-resistant welding material for LNG storage tank has excellent mechanical properties, low-temperature resistance and corrosion resistance.

[0237] The test method is as follows:

[0238] (1) Mechanical property test: the test is carried out according to the method described in GB / T 228.1-2021 “Metallic materials tensile test Part 1: room temperature test method”.

[0239] (2) Low-temperature impact energy: according to GB / T 229-2020 “Metallic materials Charpy pendulum impact test method”, the temperature is-196℃.

[0240] (3) Corrosion resistance: the test is carried out according to the method E described in GB / T 4157-2017; whether the weld cracks after 720h is recorded, and no crack is the qualified product.

[0241] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the contents in the specification, and the technical scope must be determined according to the scope of claims.

Claims

1. A low-temperature resistant and corrosion-resistant welding material for LNG storage tanks, characterized in that: The powder raw material comprises the following parts by weight: C: 0.30-0.45%, Si: 0.05-0.20%, Mn: 20.0-22.0%, Cr: 6.0-8.0%, Ni: 12.0-15.0%, Mo: 1.5-2.0%, B: 0.001-0.005%, Ti: 0.05-0.10%, Nb: 1.0-1.5%, V: 0.2-0.5%, Cu: 0.3-0.5%, RE: 0.05-0.15%, nanomaterials: 0.30-0.50%, S: <0.005%, P: <0.005%, Fe balance; The ratio of Mn to Cr is 2.75-3.35; The nanomaterials include two-dimensional nanomaterials.

2. The low-temperature resistant and corrosion-resistant welding material for LNG storage tanks according to claim 1, characterized in that: The RE is one or more of Y, La, or Ce.

3. A method for preparing a low-temperature resistant and corrosion-resistant welding material for LNG storage tanks as described in claim 1, characterized in that: Includes the following steps: S1: Oxidation treatment: The nanomaterials are subjected to surface oxidation treatment to obtain oxidized nanomaterials; S2: Surface modification treatment: The oxide nanomaterials are ball-milled with RE and Cr to obtain modified nanomaterials; S3: Raw material ratio: Under argon protection, prepare the original metal powder excluding the modified nanomaterials; S4: High-temperature vacuum melting: The prepared metal powder is subjected to high-temperature vacuum melting to obtain an alloy melt; S5: Atomization powder production: The alloy melt is treated by argon atomization and then screened to obtain spherical atomized alloy powder; S6: Wet blending method: Spherical atomized alloy powder and modified nanomaterials are added to ethanol, ultrasonically treated to obtain an ethanol suspension; dried to obtain a mixed powder. S7: Hot isostatic pressing: The mixed powder is placed in a stainless steel sleeve with a certain space reserved for degassing, and then placed in a hot isostatic press to sinter into a billet. S8: Forging and rolling: Forging and rolling bar billets to produce alloy wire rods; S9: Solution treatment; S10: Surface treatment; i.e. The alloy wire is pickled and coated to obtain the target product.

4. The method for preparing the low-temperature resistant and corrosion-resistant welding material for LNG storage tanks according to claim 3, characterized in that: The two-dimensional nanomaterial is graphene.

5. A welding method using the low-temperature resistant and corrosion-resistant welding material for LNG storage tanks as described in claim 1, characterized in that: Argon gas protection is used, with an argon gas flow rate of 15-20 L / min; the welding current is 300-400 A, and the voltage is 28-32 V; and post-weld heat treatment is performed.

6. The welding method of the low-temperature resistant and corrosion-resistant welding material for LNG storage tanks according to claim 5, characterized in that: The post-weld heat treatment is performed at 600-620℃ for 2.0-2.5 hours.

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