High-toughness austenitic stainless steel electrode for 5Ni steel and preparation method of high-toughness austenitic stainless steel electrode

Abstract

The invention provides a high-toughness austenitic stainless steel welding rod for 5Ni steel and a preparation method of the high-toughness austenitic stainless steel welding rod. The welding rod comprises a core wire and a coating coated on the surface of the core wire, and based on the total amount of the core wire, the core wire comprises the following components in percentage by mass: less than or equal to 0.09% of C, less than or equal to 0.15% of Si, 1.6-2.5% of Mn, 18.5-20.5% of Cr, 12.5-14.5% of Ni, 2.1-3.2% of Mo and 0.06-0.18% of Ti; 0.12-0.24% of Al, less than or equal to 0.007% of S, less than or equal to 0.008% of P, less than or equal to 0.006% of O, less than or equal to 0.001% of H, less than or equal to 0.012% of S + P, and the balance Fe and inevitable impurities. On the basis of the total amount of the coating, the coating comprises, by mass, 28-38% of carbonate, 15-20% of fluorite, 1-3% of lithium fluoride and sodium fluoride, 8-12% of synthetic mica, 3-6% of potassium silicotitanate, 2-4% of zircon sand, 9-15% of electrolytic manganese metal, 2-4% of ferrotitanium, 2-5% of passivated nickel-magnesium alloy, 1-3% of atomized ferrosilicon, 1-3% of lanthanum cerium fluoride, 1-3% of tungsten and molybdenum, 3-5% of nitrided ferrochromium and 1-2% of CMC. The welding rod is good in all-position welding controllability, extremely low in air hole sensitivity and excellent in low-temperature toughness, and can meet the requirements for high-quality and efficient welding of 5Ni steel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding, in particular to a high-toughness austenitic stainless steel electrode for 5Ni steel and a preparation method thereof. BACKGROUND

[0002] 5Ni steel (also known as 5% nickel steel) is a kind of medium-nickel low-temperature steel, which is designed for low-temperature environment below-100℃, has good low-temperature toughness, weldability and economy, and is widely used in the cryogenic storage and transportation of liquefied ethylene gas (LEG) and liquefied petroleum gas (LPG). Since the 5Ni steel is used in a relatively low temperature environment, in order to make the welded joint have good low-temperature toughness, the same nickel-based welding material as 9Ni steel is currently mainly used for welding. When nickel-based welding material is used, the following problems exist: (1) the nickel-based welding material is expensive; (2) the nickel-based welding material has poor spreading and wetting properties, and is prone to defects such as slag inclusion and incomplete fusion; (3) the nickel-based welding material has high sensitivity to hot cracking and porosity compared with low-alloy steel and austenitic stainless steel.

[0003] Due to the lack of special welding materials for 5Ni steel, the welding cost is increased, which affects the further popularization and application. CN111618479B is a kind of electrode for 5%Ni steel and a preparation method thereof, which is composed of a welding core and a coating, the coating is coated on the outer wall of the welding core, the weight coefficient of the coating in the total weight of the electrode is 0.35~0.65, a stainless steel ER316L welding core is used, the welding core is composed of the following components: C: ≤0.02%; Si: ≤0.40%; Mn: 1.50~2.50%; Cr: 17.5~20.5%; Ni: 11.0~13.0%; Mo: 2.0~3.0; P: ≤0.020%; S: ≤0.015%; Fe: balance. The electrode has excellent alternating current all-position welding process performance, stable arc, basically no spatter, excellent operability, excellent deslagging and beautiful weld forming. The deposited metal has excellent-120℃ ultra-low temperature toughness, tensile strength ≥630MPa, elongation ≥35%, and-120℃ impact ≥80J. However, the low-temperature toughness is limited, and the welded joint has a small amount of porosity. SUMMARY

[0004] Therefore, the present application aims to provide a high-toughness austenitic stainless steel electrode for 5Ni steel and a preparation method thereof, which solves the problems of insufficient low-temperature toughness and high porosity sensitivity during welding by the mutual cooperation of the welding core and the coating components.

[0005] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0006] In one aspect, the present application provides a high-toughness austenitic stainless steel electrode for 5Ni steel, which comprises an electrode core and a coating on the surface of the electrode core, and the electrode core comprises, based on the total mass of the electrode core, C: 0.09% or less, Si: 0.15% or less, Mn: 1.6-2.5%, Cr: 18.5-20.5%, Ni: 12.5-14.5%, Mo: 2.1-3.2%, Ti: 0.06-0.18%, Al: 0.12-0.24%, S: 0.007% or less, P: 0.008% or less, O: 0.006% or less, H: 0.001% or less, and S+P: 0.012% or less, and the remainder being Fe and inevitable impurities.

[0007] The coating comprises, based on the total mass of the coating, the following powders: carbonate: 28-38%, fluorite: 15-20%, lithium fluoride + sodium fluoride: 1-3%, synthetic mica: 8-12%, potassium silico-titanate: 3-6%, zirconium silicate: 2-4%, electrolytic manganese: 9-15%, ferro-titanium: 2-4%, passivated nickel-magnesium alloy: 2-5%, atomized ferrosilicon: 1-3%, lanthanum cerium fluoride: 1-3%, tungsten + molybdenum: 1-3%, chromium iron nitride: 3-5%, and CMC: 1-2%.

[0008] Further, the carbonate is a mixture of marble, barium carbonate and strontium carbonate.

[0009] Further, the coating is uniformly coated on the electrode core by using a binder, and the binder is potassium-sodium mixed water glass with a modulus of 2.4-2.7.

[0010] Further, the binder is added in an amount of 17-20% of the total weight of the dry powder of the coating. Specifically, the potassium-sodium mixed water glass has a modulus of 2.4, 2.5, 2.6 or 2.7, and is added in an amount of 17%, 18%, 18.5%, 19%, 19.5% or 20% of the total weight of the dry powder of the coating.

[0011] Further, the coating accounts for 30-35% of the total amount of the electrode. Specifically, the coating accounts for 30%, 31%, 32%, 33%, 34%, 35% or the like of the total amount of the electrode.

[0012] The present application also provides a preparation method of the high-toughness austenitic stainless steel electrode for 5Ni steel as described above, which comprises the following steps:

[0013] S1. preparing the electrode core according to the proportions;

[0014] S2. mixing the powders in the coating;

[0015] S3. adding a binder to continue stirring to uniformly mix the powders;

[0016] S4. Rolling to make the powder material plastic and flowable, and pressing into a powder mass;

[0017] S5. Placing the powder mass into an oil pressure electrode coating machine to make the coating evenly coated on the outside of the welding core, the coating pressure is 8-20 MPa, the in-line grinding head and grinding tail, and the eccentricity value should be no more than 3% of the diameter of the welding core;

[0018] S6. Baking in an electrode oven.

[0019] Further, in step S2, the powder materials in the coating are placed in a V-shaped mixer for dry mixing, and the mixing time is 15-35 min.

[0020] Further, in step S4, the rolling is performed in a rolling mixer for 15-25 min.

[0021] Further, in step S6, the baking process is performed at 50-70℃ for 3-4 h, at 150-200℃ for 2-3 h, and at 320-380℃ for 1-2 h.

[0022] To better illustrate the technical approach of the present application, the functions of the main components in the welding core and the coating are described in detail as follows.

[0023] The main functions of Ti and Al in the welding core are deoxidation and nitrogen fixation, which can significantly reduce the sensitivity of pores. However, if the addition amount is too low, the deoxidation and nitrogen fixation effects will not be obvious, and if the addition amount is too high, slag inclusion will occur.

[0024] Mn, Cr, Ni, and Mo in the welding core are the main alloying elements. When the addition amount is too low, a large amount of alloy powder needs to be added in the coating, which makes the coating difficult to be applied. When the addition amount in the welding core is too high, the resistance of the welding core is too large, the welding core is easy to turn red during welding, which leads to cracking of the holding end and failure to perform welding.

[0025] The carbonates in the coating are a mixture of marble, barium carbonate, and strontium carbonate. On the one hand, these carbonates can form slag and gas to protect the weld metal from atmospheric invasion, and on the other hand, they can increase the basicity of the slag and improve the purity and low-temperature toughness of the welded metal. However, when the addition amount is less than 28%, the beneficial effect is insufficient, and when the addition amount is greater than 38%, the welding process will be deteriorated.

[0026] The main function of fluorite in the coating is to dilute the slag and remove hydrogen, which reduces the sensitivity of hydrogen pores. When the addition amount is less than 15%, the melting point of the slag is high, the spread and wetting of the weld are poor, and defects such as slag inclusion and pores are easy to occur. When the addition amount is greater than 20%, the arc stability is poor, and the viscosity of the slag is too small, which makes it difficult to form vertical and overhead welds.

[0027] Lithium fluoride and sodium fluoride in the coating have similar effects with fluorite, but the dehydrogenation effect is better than fluorite. When the total addition amount of lithium fluoride and sodium fluoride is less than 1%, the dehydrogenation effect is insufficient, and the porosity sensitivity is large; when the total addition amount is greater than 3%, the slag viscosity is too small, and vertical and overhead welding is difficult.

[0028] Synthetic mica in the coating is calcined synthetic mica above 200℃, which does not contain water of hydration or crystal water. The main effects are arc stabilization, droplet refinement, spatter reduction, and improvement of press coating. When the addition amount is less than 8%, the arc stability is poor, the droplet is large, and the powder flowability is poor, and the eccentricity is difficult to control; when the addition amount is greater than 12%, the non-metallic inclusions in the weld metal increase, and the plasticity and toughness of the weld metal deteriorate.

[0029] Potassium silicate in the coating is a molten and crushed silicate, and the main effects are arc stabilization, slag formation, and improvement of weld formation. When the addition amount is less than 3%, the arc stability is poor, and the spatter is large; when the addition amount is greater than 6%, it is easy to absorb moisture, and the porosity sensitivity is large.

[0030] The addition amount of zircon in the coating is less than 2%, and vertical and overhead welding is difficult; when the addition amount is greater than 4%, the melting point is too high, the spreading is poor, and non-metallic inclusions are easily formed.

[0031] Electrolytic manganese in the coating can combine with S on one hand to reduce the hot crack sensitivity, and on the other hand as a main alloying element to play a good strengthening and toughening effect. When the addition amount is less than 9%, the strength is low, and the low temperature toughness is poor; when the addition amount is greater than 15%, the welding fume increases.

[0032] Titanium iron in the coating mainly plays a role in deoxidation and nitrogen fixation. When the addition amount is less than 2%, the deoxidation and nitrogen fixation effects are not obvious, the weld metal porosity sensitivity is large, and the low temperature toughness is poor; when the addition amount is greater than 4%, the spatter increases, and the low temperature toughness of the weld metal decreases.

[0033] Passivated nickel-magnesium alloy in the coating mainly plays a role in deoxidation. When the addition amount is less than 2%, the deoxidation effect is insufficient, and the low temperature toughness of the weld metal is poor; when the addition amount is greater than 5%, the spatter increases, and the weld formation is poor.

[0034] Atomized silicon iron in the coating mainly plays a role in deoxidation. When the addition amount is less than 1%, the deoxidation effect is insufficient, and the low temperature toughness of the weld is poor; when the addition amount is greater than 3%, the Si content in the weld is too high, and the hot crack sensitivity increases.

[0035] Lanthanum cerium fluoride in the coating mainly plays a role in dehydrogenation, purifying the weld metal, reducing the porosity sensitivity, and improving the low temperature toughness. When the addition amount is less than 1%, the beneficial effect is insufficient, the porosity sensitivity is large, and the low temperature toughness of the weld is poor; when the addition amount is greater than 3%, the non-metallic inclusions increase, and the low temperature toughness deteriorates.

[0036] Tungsten and molybdenum in the coating are main alloying agents, which can make the weld metal have suitable strength and low-temperature toughness. If the addition amount is too low, the strengthening effect is insufficient, and if the addition amount is too high, the low-temperature toughness is deteriorated, and the suitable addition amount is 1-3%.

[0037] Iron chromium nitride in the coating is the main alloying agent, which transfers nitrogen and chromium to the weld. If the addition amount is less than 3%, the nitrogen content in the weld metal is low, and the weld strength is insufficient, and if the addition amount is greater than 5%, the porosity sensitivity increases.

[0038] When the addition amount of CMC in the coating is less than 1%, the improvement of the press coating property is not obvious, and when the addition amount is greater than 2%, the porosity sensitivity increases.

[0039] Potassium sodium water glass in the coating is the main binder. When the addition amount of water glass is greater than 20%, the coating strength is low, and the grinding head and grinding tail are easy to break; and when the addition amount is less than 17%, the press coating pressure is too high, the press coating is difficult, and the eccentricity is not easy to control.

[0040] Compared with the prior art, the high-toughness austenitic stainless steel electrode for 5Ni steel and the preparation method thereof have the following advantages:

[0041] (1) The welding core and the coating have a multi-path synergistic effect, and the porosity sensitivity is reduced.

[0042] (2) The content of S and P in the welding core is controlled to be S+P≤0.012%, so that the formation of low-melting-point phases in the grain boundary or interdendritic is reduced; the contents of Cr, Mo and Ni are controlled, so that the solid-liquid phase temperature interval is reduced, and the hot crack sensitivity is reduced.

[0043] (3) The basicity of the molten slag is improved, so that the purity of the weld metal is improved; Si-Ti-Mg-Al combined deoxidation is adopted, so that the oxygen content of the weld metal is reduced to below 250ppm; a certain amount of rare earth lanthanum and cerium is added, so that the grain is refined, the weld metal is purified, and the low-temperature toughness is improved.

[0044] (4) The all-position welding controllability is good, the arc is stable, the spatter is small, the slag is easy to remove, and the weld forming is good.

[0045] (5) The deposited metal has high strength (R p0.2 ≥420MPa, R m ≥590MPa), and the joint impact energy at-140℃ reaches 100J or more, which has good matching with 5Ni steel. DETAILED DESCRIPTION

[0046] The application will be further described in conjunction with specific embodiments. Firstly, it should be noted that the data in the following examples are obtained by the inventors through a large number of experiments, and only a part of them are shown in the specification due to the limited space, and the ordinary skilled in the art can understand and implement the application based on the data. The examples are only used to illustrate the application and not to limit the scope of the application. Furthermore, it should be understood that after reading the content of the application, the skilled in the art can make various modifications or changes to the application, and these modifications or changes also fall within the scope of the application.

[0047] Considering that the electrode has the characteristics of simple equipment, strong environmental adaptability and suitable for multi-position welding, it is widely used in engineering, and therefore the application provides a high-toughness austenitic stainless steel electrode for 5Ni steel.

[0048] The electrode comprises an electrode core and a coating on the surface of the electrode core, and the electrode core components include, based on the total amount of the electrode core, C≤0.09%, Si≤0.15%, Mn: 1.6~2.5%, Cr: 18.5~20.5%, Ni: 12.5~14.5%, Mo: 2.1~3.2%, Ti: 0.06~0.18%, Al: 0.12~0.24%, S≤0.007%, P≤0.008%, O≤0.006%, H≤0.001%, and S+P≤0.012%, and the rest is Fe and unavoidable impurities.

[0049] Based on the total amount of the coating, the coating components include the following powder materials: carbonate: 28~38%, fluorite: 15~20%, lithium fluoride + sodium fluoride: 1~3%, synthetic mica: 8~12%, potassium silicate: 3~6%, zirconium sand: 2~4%, electrolytic manganese: 9~15%, titanium iron: 2~4%, passivated nickel-magnesium alloy: 2~5%, atomized silicon iron: 1~3%, lanthanum cerium fluoride: 1~3%, tungsten + molybdenum: 1~3%, chromium iron nitride: 3~5%, and CMC: 1~2%.

[0050] The lithium fluoride and the sodium fluoride can be mixed in any ratio, and only the total amount of the two is required to be 1~3%; the tungsten and the molybdenum can be mixed in any ratio, and only the total amount of the two is required to be 1~3%.

[0051] The coating is uniformly coated on the electrode core by using a binder, and the binder is a mixed water glass of potassium and sodium with a modulus of 2.4~2.7, and the addition amount is 17~20% of the total weight of the dry powder of the coating.

[0052] As a specific example of the application, the coating accounts for 30~35% of the total amount of the electrode.

[0053] The carbonate is a mixture of marble, barium carbonate and strontium carbonate. The three can be mixed in any ratio, but it is necessary to ensure that all three are present and the total amount is 28-38%.

[0054] The requirements of the above used welding core and coating powder are shown in Table 1.

[0055] Table 1

[0056]

[0057]

[0058] The 5Ni steel high-toughness austenitic stainless steel electrode of the present application has the following advantages:

[0059] (1) The welding core and coating have multiple pathways for synergistic effect, which reduces the sensitivity of pores, and the specific methods are as follows: trace amounts of lanthanum and cerium are added to the welding core to deoxidize, fix nitrogen and reduce the sensitivity of pores. The coating is made of non-aqueous raw materials (for aqueous raw materials, the combined water and crystal water are removed by high-temperature melting treatment), which can reduce the source of hydrogen in the weld metal; a plurality of fluoride compounds are added to the coating to form a protective gas while dehydrogenating, thereby reducing the invasion of impurities such as oxygen and nitrogen in the air; and an appropriate amount of carbonate is added to the coating to improve the oxidizing property of the arc atmosphere, reduce the solid solution amount of hydrogen in the weld metal, and reduce the sensitivity of pores.

[0060] (2) Hot crack sensitivity control: control the content of S and P in the welding core to make S+P≤0.012%, reduce the formation of low-melting-point phases at grain boundaries or interdendritic; control the content of Cr, Mo and Ni to reduce the solid-liquid phase temperature interval and reduce the hot crack sensitivity.

[0061] (3) Low-temperature toughness control: the alkalinity of the slag is improved, thereby improving the purity of the weld metal; Si-Ti-Mg-Al combined deoxidation is used to reduce the oxygen content in the weld metal to below 250ppm; a certain amount of rare earth lanthanum and cerium is added to refine the grain, purify the weld metal and improve the low-temperature toughness.

[0062] (4) Good operability, stable arc, less spatter, easy slag removal and good weld formation in all-position welding.

[0063] (5) The deposited metal has high strength (R p0.2 ≥420MPa, R m ≥590MPa), and the joint impact energy at -140℃ reaches more than 100J, which has good matching with 5Ni steel.

[0064] The preparation method of the 5Ni steel high-toughness austenitic stainless steel electrode of the present application comprises the following steps:

[0065] S1. Prepare the welding core according to the proportion;

[0066] Specifically, the welding core can be smelted in any way meeting the component requirements, such as electron beam smelting and electroslag remelting. Since the smelting of the ingot is the prior art, it is not described here. The smelted ingot is subjected to open forging, hot rolling and solid solution treatment to be a Φ5-Φ7 mm wire rod, is subjected to acid pickling and then is drawn to the required diameter by a disc-type wire drawing machine, and then is straightened and cut to a welding rod of a specified size. Further, the smelted ingot is subjected to open forging, hot rolling and solid solution treatment to be a Φ5.5 mm wire rod.

[0067] S2. mixing each powder in the coating;

[0068] Specifically, in step S2, each powder in the coating is placed in a V-type mixer for dry mixing, and the mixing time is 15-35 min.

[0069] S3. adding a binder to continue stirring to uniformly mix the powders;

[0070] Specifically, in step S3, the stirring time is 6-10 min.

[0071] S4. rolling to make the powders plastic and flowable, and pressing into a powder mass;

[0072] Specifically, in step S4, the rolling is performed in a rolling mixer for 15-25 min.

[0073] S5. placing the powder mass in an oil pressure type welding rod coating press to uniformly coat the coating on the outside of the welding core, the coating pressure is 8-20 MPa, the in-line grinding head and tail are ground, and the eccentricity value should be not greater than 3% of the diameter of the welding core;

[0074] S6. baking in a welding rod furnace.

[0075] Specifically, in step S6, the baking process is 50-70℃ for 3-4 h, 150-200℃ for 2-3 h, and 320-380℃ for 1-2 h.

[0076] The obtained welding rod can be Φ2.5 mm, Φ3.2 mm and Φ4.0 mm or other required specifications.

[0077] Embodiment

[0078] In experimental examples 1-3, the welding core formulations shown in Table 2 are used, in experimental examples 4-6, the coating formulations shown in Table 3 are used, and the welding rods are prepared by using an oil pressure type welding rod production device, and the specification is Φ3.2 mm.

[0079] The preparation method of the welding rod is as follows:

[0080] S1. preparing the welding core according to the proportion;

[0081] S2. Put each powder in the V-type mixer and dry mix for 35 min;

[0082] S3. Add the binder and continue to stir for 10 min to make the powder mix uniformly, the binder is mixed water glass with modulus of 2.4, and the amount is 17% of the total weight of the dry coating powder;

[0083] S4. Perform rolling in the rolling mixer for 25 min to make the powder mix plastic and flowable, and press into a powder mass;

[0084] S5. Put the powder mass into the oil pressure type welding rod coating press to make the coating uniformly coated on the outside of the welding core, the coating pressure is 20 MPa, the in-line grinding head and tail, and the eccentricity value should be no more than 3% of the diameter of the welding core;

[0085] S6. Perform baking in the welding rod furnace, the baking process is 50℃ for 3.5 h, 200℃ for 2 h, and 380℃ for 2 h.

[0086] Table 2

[0087]

[0088] Table 3

[0089]

[0090]

[0091] In the above Tables 2-3, the marble + barium carbonate + strontium carbonate usage ratio of Experimental Example 4 is 1:1:1, the marble + barium carbonate + strontium carbonate usage ratio of Experimental Example 5 is 1:2:3, and the marble + barium carbonate + strontium carbonate usage ratio of Experimental Example 6 is 2:1:1.

[0092] Comparative Example 1

[0093] The welding core formula of Comparative Example 1 is the same as that of Experimental Example 1, and the coating formula is the same as that of Experimental Example 4, the only difference is that the carbonate is 28 parts of marble, that is, the carbonate is all selected from marble. And the welding rod is prepared by using the welding rod preparation method of the application. The preparation method is the same as that of Example 1.

[0094] Comparative Example 2

[0095] The component selection and preparation method of Comparative Example 2 are the same as those of Example 3 in CN111618479B.

[0096] The welding rod prepared from the welding core and the coating according to the present application, and the welding rod prepared from Comparative Example 1 and Comparative Example 2 are subjected to deposition and multi-position (flat welding, vertical welding, horizontal welding and overhead welding) butt joint welding of the matching 5Ni steel. AC welding is adopted, the flat welding current is 120-150 A, the vertical welding and overhead welding current is 100-120 A, and the inter-pass temperature is controlled below 100 DEG C. Post-welding mechanical properties of the deposited metal, joint macrostructure analysis and radiographic inspection are carried out. The mechanical properties of the deposited metal are shown in Table 4. The deposition efficiency and defect conditions are shown in Table 5. In Table 5, the welding joints in the flat, horizontal, vertical and overhead welding positions of the welding rod are subjected to defect analysis according to GB / T13298 and radiographic inspection according to GB / T3323.

[0097] Table 4

[0098]

[0099] Table 5

[0100]

[0101]

[0102] In order to facilitate comparison, in the above Examples 1-9, the coating accounts for 30% of the total amount of the welding rod.

[0103] As shown in Table 4, the welding rod according to Examples 1-9 has moderate strength of the deposited metal, excellent low-temperature toughness at -140 DEG C, and good matching with the 5Ni steel. The arc is stable during welding, the spatter is small, the slag is easy to remove, the weld formation is good, and no air hole is present. The plastic elongation strength of the welding rod according to Comparative Example 2 and Examples 1-9 is not much different, but compared with Comparative Example 2, Examples 1-9 can greatly improve the tensile strength and elongation after fracture, and have better toughness at low temperature, which is suitable for low-temperature use conditions of the 5Ni steel.

[0104] As shown in Table 5, for various welding positions, the three carbonates in Examples 1-9 interact with each other, the macroscopic appearance of the welding joint is good, and after welding, the joint is free of defects such as air hole, slag inclusion and incomplete fusion, and the radiographic inspection grade is grade I. The carbonates in Comparative Example 1 and Comparative Example 2 are only one kind, and the welding joint is prone to a small amount of air hole, which also affects the low-temperature toughness. Meanwhile, compared with Comparative Example 2, the lithium fluoride + sodium fluoride used in Examples 1-9 can reduce the hygroscopicity and improve the anti-porosity, and although the potassium cryolite used in Comparative Example 2 can reduce F + - The potassium cryolite has hygroscopicity, resulting in a small amount of air hole.

[0105] ​Although the present application has been disclosed with reference to the above embodiments, the application is not limited to the above embodiments. It will be apparent to those skilled in the art that various modifications and changes can be made thereto without departing from the spirit and scope of the application. It is therefore intended that the scope of the application be limited only by the scope of the claims.

Claims

1. A high-toughness austenitic stainless steel welding electrode for 5Ni steel, characterized in that, The welding electrode includes a core and a coating on the surface of the core. Based on the total amount of the core, the composition of the core, by mass percentage, includes: C≤0.09%, Si≤0.15%, Mn: 1.6~2.5%, Cr: 18.5~20.5%, Ni: 12.5~14.5%, Mo: 2.1~3.2%, Ti: 0.06~0.18%; Al: 0.12~0.24%, S≤0.007%, P≤0.008%, O≤0.006%, H≤0.001%, and S+P≤0.012%, with the remainder being Fe and unavoidable impurities.

2. The high-toughness austenitic stainless steel welding electrode for 5Ni steel according to claim 1, characterized in that, Based on the total amount of the drug coating, the drug coating components, by mass percentage, include the following powders: carbonates: 28-38%, fluorite: 15-20%, lithium fluoride + sodium fluoride: 1-3%, synthetic mica: 8-12%, potassium titanate: 3-6%, zircon sand: 2-4%, electrolytic manganese metal: 9-15%, ferrotitanium: 2-4%, passivated nickel-magnesium alloy: 2-5%, atomized ferrosilicon: 1-3%, lanthanum-cerium fluoride: 1-3%, tungsten + molybdenum: 1-3%, ferrochrome nitride: 3-5%, CMC: 1-2%.

3. The high-toughness austenitic stainless steel welding electrode for 5Ni steel according to claim 2, characterized in that, The carbonate is a mixture of marble, barium carbonate, and strontium carbonate.

4. The high-toughness austenitic stainless steel welding electrode for 5Ni steel according to claim 2, characterized in that, The flux coating is uniformly applied to the core using an adhesive, wherein the adhesive is a potassium-sodium mixed water glass with a modulus of 2.4 to 2.

7.

5. The high-toughness austenitic stainless steel welding electrode for 5Ni steel according to claim 4, characterized in that, The amount of binder added is 17-20% of the total weight of the dry powder of the drug coating by mass percentage.

6. The high-toughness austenitic stainless steel welding electrode for 5Ni steel according to claim 1, characterized in that, The coating comprises 30-35% of the total electrode weight.

7. The method for preparing high-toughness austenitic stainless steel welding electrodes for 5Ni steel according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: S1. Prepare the welding core according to the proportions; S2. Mix all the powders in the herbal skin; S3. Add the binder and continue stirring to mix the powder evenly; S4. Compaction gives the powder plasticity and fluidity, and compresses it into powder pellets; S5. Place the powder clump into a hydraulic electrode coating machine to evenly coat the outside of the electrode core. The coating pressure is 8~20MPa. The eccentricity of the online grinding head and tail should not exceed 3% of the electrode core diameter. S6. Baking in a welding rod furnace.

8. The method for preparing high-toughness austenitic stainless steel welding electrodes for 5Ni steel according to claim 7, characterized in that, In step S2, each powder component in the drug coating is placed in a V-type mixer for dry mixing, and the mixing time is 15~35 minutes.

9. The method for preparing high-toughness austenitic stainless steel welding electrodes for 5Ni steel according to claim 7, characterized in that, In step S4, the material is compacted in a rolling mixer for 15-25 minutes.

10. The method for preparing high-toughness austenitic stainless steel welding electrodes for 5Ni steel according to claim 7, characterized in that, In step S6, the baking process is carried out at 50~70℃ for 3~4 hours, at 150~200℃ for 2~3 hours, and at 320~380℃ for 1~2 hours.

Images