Iron-nickel alloy welding wire having excellent low-temperature use performance and method for manufacturing the same

Abstract

The application discloses an iron-nickel alloy welding wire with excellent low-temperature use performance and a manufacturing method thereof, and chemical components are as follows in percentage by weight: 34.5%<=Ni<=37.5%, 0.040%<=C<=0.080%, 0.01%<=Si<=0.30%, 0.1%<=Mn<=0.6%, P<=0.0030%, S<=0.0015%, O<=0.0030%, N<=0.0020%, 0.0010%<=Mg<=0.0040%, 0.0001%<=Al<=0.0025%, V<=0.0020%, Ti<=0.0020%, Nb<=0.0020%, 0.0001%<=Ca<=0.0020%, B<=0.0010%, 0.0001%<=La+Ce<=0.0020%, and the balance is Fe and inevitable impurities, which has excellent low-temperature expansion performance and post-welding weld impact toughness.

Description

TECHNICAL FIELD

[0001] The present application relates to iron-nickel alloy welding wire technology, more particularly, to an iron-nickel alloy welding wire with excellent low-temperature use performance and a manufacturing method thereof, and particularly to an iron-nickel alloy welding wire for welding of liquefied gas equipment. BACKGROUND

[0002] The global energy transformation is in full swing, and the demand for low-temperature gas transportation equipment is rising with the water level. Due to the low density of gas, in order to reduce transportation costs, the current mainstream transportation method is still to cool the gas to below the boiling point to change it into a liquid, thereby improving transportation efficiency.

[0003] The main liquefied gases transported at present are liquefied ammonia, liquefied carbon dioxide, liquefied ethane, liquefied hydrogen, liquefied methane, etc. In order to ensure the safety of tanked and transported liquefied gas, the transportation assembly usually needs to have suitable low-temperature expansion performance and excellent low-temperature impact toughness. In order to meet the requirements of structural performance after welding, special design is needed for the traditional welding wire.

[0004] Chinese Patent Publication No. CN103084753A discloses a nickel-iron precision alloy welding wire, the chemical composition of which is as follows: C 0.1~0.18%, Mn 0.4~0.5%, Si 0.2~0.3%, Ni 35~37%, Ti 0.4~0.5%, Nb 1.12~1.2%, S≤0.005%, P≤0.01%, the rest being Fe and unavoidable impurities; wherein, C / (Nb+Ti)<0.2; the performance index of the deposited metal is: tensile strength (Rm)≥480 MPa, 20℃ impact toughness AKV2≥50 J / cm 2 , 20~100℃ linear expansion coefficient≤1.2×10 -6 / ℃, aiming at the use condition of the weld metal in room temperature environment, Ti and Nb are used to strengthen the weld metal, thereby improving the strength and toughness of the weld metal; but the nickel-iron precision alloy welding wire researched by this technology is more inclined to the performance at normal temperature, and the use performance of the weld at low temperature (such as thermal expansion performance at-180℃~0℃ and impact performance at-198℃, etc.) is not researched.

[0005] Chinese patent publication No. CN107866647A discloses a Fe-Ni invar alloy welding wire and a manufacturing method thereof, the chemical composition of which has a weight ratio of C: 0.04~0.10%, Si≤0.25%, Mn: 0.2~0.4%, P≤0.08%, S≤0.003%, Ni: 35~38%, Cr: 0.2~0.5%, V: 0.08~0.15%, and the rest is Fe and inevitable impurities. The technology improves the strength and toughness of the deposited metal by increasing the content of C and appropriately adding elements such as Cr and V through carbide strengthening and solid solution strengthening, and ensures to obtain lower expansion performance; the technology mainly strengthens the grain boundary through the carbide of Cr and V, and only studies the room temperature performance; but due to the existence of a large number of coarse carbides, the low temperature impact performance of the material is deteriorated, and becomes a crack source of cracking; therefore, the Fe-Ni invar alloy welding wire of the technology is not suitable for welding use of low temperature liquefied gas equipment.

[0006] In summary, at present, in the composition design of low expansion alloy welding wire, by adding strong carbide forming elements, dispersed carbides are formed on the matrix, the strength is improved through precipitation strengthening, and the toughness is improved through grain refinement at the same time; but this technical means is limited to improve the strength and toughness of the welding wire itself, and has very limited effect on improving the low temperature toughness of the weld bead after welding. This is because after the welding wire is welded and melted, it is cooled into a cast structure, which is coarse dendrite; these dispersed carbides cannot effectively refine the grains, so as to improve the toughness; on the contrary, too much carbide precipitates at the grain boundary, which reduces the grain boundary bonding force and the low temperature impact toughness.

[0007] In view of the above, it is necessary to study a welding wire with excellent low temperature use performance, which can meet the high comprehensive performance requirements of low temperature liquefied gas transportation components. SUMMARY

[0008] In view of the defects in the prior art, the purpose of the present application is to provide an iron-nickel alloy welding wire with excellent low temperature use performance and a manufacturing method thereof, by increasing the content of C element in the welding wire, adding La, Ce and Mg elements, reducing the content of Al element, and strictly controlling the content of S, P, O and N elements, so as to obtain an iron-nickel alloy welding wire with excellent low temperature expansion performance and weld bead impact toughness after welding, which meets the high comprehensive performance requirements of low temperature liquefied gas transportation components, and is particularly suitable for the manufacture of low temperature liquefied gas transportation components.

[0009] To achieve the above purpose, the present application adopts the following technical solutions:

[0010] The iron-nickel alloy welding wire with excellent low-temperature use performance provided by the first aspect of the present application has the following chemical composition in terms of percentage by weight: 34.5%≤Ni≤37.5%, 0.040%≤C≤0.080%, 0.01%≤Si≤0.30%, 0.1%≤Mn≤0.6%, P≤0.0030%, S≤0.0015%, O≤0.0030%, N≤0.0020%, 0.0010%≤Mg≤0.0040%, 0.0001%≤Al≤0.0025%, V≤0.0020%, Ti≤0.0020%, Nb≤0.0020%, 0.0001%≤Ca≤0.0020%, B≤0.0010%, 0.0001%≤La+Ce≤0.0020%, and the balance including Fe and inevitable impurities.

[0011] The percentage by weight of the chemical composition of the iron-nickel alloy welding wire also satisfies the following formula:

[0012] 0≤S1≤0.010%;

[0013] S1=(La+Ce)×2+C / 20+Al / 3×2+Mg×2+Ca+V / 3+Ti / 6+Nb / 6-O×3-N×3.

[0014] Preferably, 0.002%≤S1≤0.009%.

[0015] Preferably, 0.18%≤Mn≤0.6%, 0.0008%≤Al≤0.0020%, and 0.0004%≤La+Ce≤0.0018%.

[0016] Preferably, the coefficient of thermal expansion of the iron-nickel alloy welding wire between -180℃ and 0℃ is (1.0~2.0)×10 -6 m / m / ℃.

[0017] Preferably, the coefficient of thermal expansion of the iron-nickel alloy welding wire between -180℃ and 0℃ is (1.2~1.7)×10 -6 m / m / ℃.

[0018] Preferably, the V-type impact toughness of the weld bead cladding metal of the iron-nickel alloy welding wire after welding at -196℃ is ≥150 Jcm -2 .

[0019] Preferably, the V-type impact toughness of the weld bead cladding metal of the iron-nickel alloy welding wire after welding at -196℃ is 170~180 Jcm -2 .

[0020] The component design principle of the iron-nickel alloy welding wire of the present application is as follows:

[0021] C: C plays an important role in the present application. First, increasing the C content can significantly increase the solid-liquid phase line spacing of the material, expand the solidification temperature range of the material, thereby reducing the solute equilibrium distribution coefficient K0, increasing the material composition supercooling degree, and facilitating the rapid solidification of the liquid film at the end of the welding; avoid the existence of micro-cracks due to the existence of liquid film under the state of welding thermal stress; thereby improving the low temperature impact toughness of the material. It is found through the research of the present application that when the C content is greater than or equal to 0.04%, the effect of expanding the solidification temperature range of the material is particularly significant, and the welding solidification structure can be significantly improved, thereby improving the quality of the welding cladding metal and significantly improving the low temperature impact performance of the welding cladding metal; when the C content is higher than 0.08%, the expansion coefficient of the material will be significantly increased, and the expansion performance will be deteriorated. Therefore, the C content is controlled to be 0.04% to 0.08% in the present application.

[0022] Ni: is an important alloying element to ensure that the alloy has low expansion performance, therefore, the Ni content is controlled to be 34.5% to 37.5% in the present application.

[0023] Mn: ensures that the weld metal after welding has a certain strength, at the same time, Mn can generate MnS and MnO with the effects of desulfurization and deoxidization, and reduce the hot cracking phenomenon caused by S. However, too high Mn content will cause the weld to become brittle and the toughness to become poor, therefore, the Mn content is controlled to be 0.1% to 0.6% in the present application, preferably 0.18% to 0.6%.

[0024] Si: is a deoxidizing element in the welding wire. Since Mn alone deoxidizes, the generated MnO has a large density and is not easy to float out of the molten pool, therefore, a certain amount of Si element must be added to the welding wire to deoxidize with Mn to generate SiO and MnO complex silicate (MnO•SiO), which can condense into large blocks of slag and float out in the molten pool, achieving good deoxidization effect. However, with the increase of Si content, low melting point inclusions are easily generated, leading to the generation of welding hot cracks, and at the same time, high Si can form silicate inclusions, reducing the impact toughness of the weld. Therefore, the Si content is controlled to be 0.01% to 0.30% in the present application.

[0025] Al is an important deoxidizing element. Too low an Al content results in poor deoxidation during alloy smelting, deteriorating the material's thermoplasticity and leading to welding hot cracks. Simultaneously, too low an Al content worsens the deoxidation reaction in the molten pool during welding, resulting in excessively high O content in the weld metal and deteriorating the weld's impact toughness. Too high an Al content leads to the formation of Al oxides, negatively impacting the alloy's purity and causing hot cracks in the weld metal area during welding, further deteriorating the weld's impact toughness. AlO inclusions significantly reduce the material's impact performance, especially under low-temperature impact. Therefore, while ensuring effective deoxidation, it is crucial to minimize Al content and AlO inclusions. This invention has found that when the Al content increases to a certain level, the negative effects of AlO production outweigh the positive effects of deoxidation. Therefore, this invention increases the content of Ce, La, Ca, and Mg to improve deoxidation strength and further reduces the Al content to mitigate the negative impact of AlO inclusions. Therefore, the Al content is controlled at 0.0001% to 0.0025%, preferably 0.0008% to 0.0020%.

[0026] Mg is an important deoxidizing element. Too low a Mg content results in poor deoxidation during alloy smelting, deteriorating the material's thermoplasticity and leading to welding hot cracks. Simultaneously, too low a Mg content worsens the deoxidation reaction in the molten pool during welding, resulting in excessively high O content in the weld metal and deteriorating the weld's impact toughness. Too high a Mg content leads to the formation of Mg oxides, negatively impacting the alloy's purity and causing hot cracks in the weld metal area during welding, further deteriorating the weld's impact toughness. Mg and Al are both strong oxide-forming elements and have similar effects. However, this invention has found that when using Mg for deoxidation, the size of the deoxidation product MgO is approximately 1 / 10 to 1 / 5 the size of AlO inclusions. By increasing the Mg content and decreasing the Al content, the size of the deoxidation product can be significantly refined, reducing the sensitivity of the weld metal to welding thermal stress and significantly reducing the generation of welding hot cracks, thereby improving the low-temperature impact toughness of the weld metal. Therefore, this invention controls the Mg content to be between 0.0010% and 0.0040%.

[0027] Ca (Ca) is an important deoxidizing and desulfurizing element. If the Ca content is too low, the deoxidation effect in the alloy will be poor, deteriorating the material's thermoplasticity and leading to welding hot cracks. Simultaneously, a low Ca content will worsen the deoxidation reaction in the molten pool during welding, resulting in excessively high O content in the weld metal and deteriorating the weld's impact toughness. If the Ca content is too high, Ca oxides will form, adversely affecting the alloy's purity and causing hot cracks in the weld metal area during welding, further deteriorating the weld's impact toughness. Furthermore, a low Ca content will result in poor desulfurization. Therefore, this invention controls the Ca content to be between 0.0001% and 0.0020%.

[0028] La and Ce are important deoxidizing and desulfurizing elements. As deoxidizers, they function similarly to Mg, ensuring deoxidation strength while producing deoxidation products with significantly smaller sizes than AlO. This reduces the sensitivity of the cladding metal to welding thermal stress, significantly decreasing the formation of welding hot cracks and thus improving the low-temperature impact toughness of the cladding metal. Simultaneously, La and Ce also possess inclusion-modifying capabilities, transforming elongated and angular inclusions into spherical or ellipsoidal particles, further reducing the sensitivity of the cladding metal to welding thermal stress. However, excessive addition of La and Ce increases the risk of rare earth agglomeration, forming large-sized inclusions and deteriorating the impact toughness of the weld. Therefore, this invention controls the La and Ce content to 0.0001%~0.0020%, preferably 0.0004%~0.0018%.

[0029] O: O in the alloy can form alumina inclusions, silicate inclusions, and spherical oxide inclusions with Mg, Al, Ca, Ti, and Si, which deteriorates the alloy purity and leads to hot cracking in the cladding metal during welding, adversely affecting the low-temperature impact toughness of the weld. Therefore, this invention controls the O content to ≤0.0030%.

[0030] Nitrogen (N) in the alloy can form nitrides with B, Al, Ti, and V, resulting in precipitates within the grains or at grain boundaries. This deteriorates the alloy's purity, leading to hot cracking in the cladding metal during welding and worsening the low-temperature impact toughness of the weld. Therefore, this invention controls the N content to ≤0.0020%.

[0031] V, Ti, and Nb are strong carbide-forming elements. Excessive V, Ti, and Nb will form carbides with C, reducing the deoxidation effect of C during welding. Therefore, this invention controls the V content to ≤0.0020%, Ti content to ≤0.0020%, and Nb content to ≤0.0020%.

[0032] B: In this invention, it is a harmful impurity that can combine with nitrogen (N) in the alloy to form BN inclusions, which have a very adverse effect on the low-temperature impact performance of the weld. Therefore, the B content is controlled to be ≤0.0010% in this invention.

[0033] P: In this invention, P is a harmful impurity that reduces the strength and toughness at the interface, leading to hot cracking in the cladding metal during welding and thus reducing the low-temperature impact toughness of the alloy weld. Therefore, this invention controls the P content to ≤0.0030%.

[0034] S: In this invention, S is a harmful impurity that reduces the strength and toughness at the interface, leading to hot cracking in the cladding metal during welding and thus reducing the low-temperature impact toughness of the alloy weld. Therefore, this invention controls the S content to ≤0.0015%.

[0035] Due to the specific nature of welding wire, traditional methods to improve the impact toughness of the cladding metal after welding often involve reducing harmful sulfur (S) and phosphorus (P) elements, and adding a certain amount of manganese (Mn) to reduce the formation of low-melting-point substances at grain boundaries, thereby improving grain boundary strength and impact performance. Alternatively, vacuum degassing or the addition of deoxidizing elements can reduce the O and N gas content in the welding wire to improve the impact toughness of the cladding metal after welding. However, welding wires that reduce O and N gas content through vacuum degassing only reduce the O and N content in the base material; this is a preparatory measure for increasing the O and N content of the cladding metal after welding. It cannot prevent the addition of O during the welding process, leading to an increase in the gas content of the cladding metal after welding. This invention reveals that while adding deoxidizing elements such as Al, Mg, and Ca can effectively reduce the gas content in metals during smelting and welding, it cannot prevent the formation of deoxidation products such as AlO, MgO, and CaO during the deoxidation process. These deoxidation products, especially coarse AlO, have poor ability to coordinate deformation with the matrix and are prone to generating welding hot cracks at the interface under welding thermal stress, which adversely affects the low-temperature impact performance of the welded cladding metal.

[0036] The present invention has found that simply reducing the content of S, P, O and N elements through the smelting process, even if the content of the welding wire base material itself is very low, cannot guarantee that the cladding metal after welding will achieve the high impact toughness expected by the present invention. Avoiding the increase of gas content after welding is the ultimate means to improve the impact toughness of the cladding metal after welding.

[0037] Therefore, based on previous methods of improving the purity of welding wire and reducing harmful elements such as sulfur (S) and phosphorus (P), this invention primarily increases the carbon (C) content in the welding wire to increase the material's supercooling, accelerates solidification during welding, and prevents the formation of a liquid film, thereby avoiding microcracks under welding thermal stress. Simultaneously, the appropriate addition of La, Ce, and Mg elements, while reducing the Al content, ensures effective deoxidation and forms fine La, Ce, and Mg deoxidation products, reducing coarse AlO deoxidation products, decreasing stress concentration during welding, and effectively preventing welding hot cracks. Therefore, this invention controls 0 ≤ S1 ≤ 0.010%, where S1 = (La + Ce) × 2 + C / 2O + Al / 3 × 2 + Mg × 2 + Ca + V / 3 + Ti / 6 + Nb / 6 - O × 3 - N × 3; preferably, S1 is 0.002% ≤ S1 ≤ 0.009%.

[0038] A second aspect of the present invention provides a method for manufacturing an iron-nickel alloy welding wire with excellent low-temperature performance as described in the first aspect of the present invention, comprising the following steps:

[0039] Smelting; smelting according to the above-mentioned composition of iron-nickel alloy welding wire;

[0040] Forging involves heating the smelted ingot to 1000~1200℃ (e.g., 1020~1120℃) and holding it at that temperature for 60~180min (e.g., 60~160℃), then forging it into a forging billet.

[0041] Hot rolling involves heating the forged billet before rolling, controlling the heating temperature at 1000~1200℃, and holding the temperature for 60~180min (e.g., 60~150℃), and then hot rolling it into a coil.

[0042] Wire drawing involves drawing coiled wire into iron-nickel alloy welding wire.

[0043] This invention strictly controls the heating temperature and holding time before forging and hot rolling in the manufacturing process of iron-nickel alloy welding wire. The heating temperature before forging and hot rolling is controlled at 1000~1200℃. Excessively high or low heating temperatures will lead to deterioration of deformation plasticity, resulting in processing cracks. Simultaneously, the heating and holding time is controlled at 60~180 minutes. Too short a heating time will result in uneven heating; too long a heating time will lead to material over-oxidation and reduced surface plasticity.

[0044] Preferably, the smelting adopts an electric furnace, an electric furnace + electroslag remelting, a vacuum induction + electroslag remelting, a vacuum induction + vacuum self-consumption smelting, or a vacuum induction + electroslag remelting + vacuum self-consumption smelting method.

[0045] The present invention provides an iron-nickel alloy welding wire with excellent low-temperature performance and its manufacturing method, which has the following beneficial effects:

[0046] 1) Traditional welding wires improve the toughness of the welded cladding metal by controlling the content of impurity elements such as P, S, O, and N, but cannot meet the requirement of a V-shaped impact toughness of ≥150 Jcm at -196℃ for the welded cladding metal. -2 The requirements are due to the unique characteristics of the welding wire itself; in the composition design of this invention, not only the performance of the welding wire itself must be considered, but also the performance of the cladding metal after the welding wire is clad.

[0047] 2) This invention, through research, discovered that repeated heating of the welding wire during the cladding process generates significant thermal stress within the cladding metal, leading to microscopic thermal cracks at interfaces (such as dendrite interfaces and inclusion interfaces), resulting in deterioration of the cladding metal's low-temperature impact performance. Therefore, in terms of composition design, this invention controls the content of S, P, O, and N within a low range. Furthermore, by increasing the C content in the welding wire, the material composition is supercooled, accelerating solidification during welding and preventing the formation of a liquid film, thus avoiding microcracks at the dendrite interfaces under welding thermal stress. Simultaneously, the appropriate addition of La, Ce, and Mg elements and the reduction of Al content ensure deoxidation while forming fine La, Ce, and Mg deoxidation products, reducing coarse AlO deoxidation products, minimizing stress concentration during welding, and effectively preventing the formation of welding hot cracks.

[0048] 3) Based on the composition design, the iron-nickel alloy welding wire of the present invention also ensures the plasticity of the welding wire during the preparation process and prevents cracking during the thermal process by controlling the heating temperature and heating time during forging and rolling.

[0049] 4) The coefficient of thermal expansion of the iron-nickel alloy welding wire prepared by this invention is (1.0~2.0)×10⁻¹⁰ between -180℃ and 0℃. -6 m / m / ℃, the V-shaped impact test result of the weld cladding metal after welding using this iron-nickel alloy welding wire at -196℃ is ≥150Jcm. -2 This invention ensures the low expansion performance of the iron-nickel alloy welding wire and improves the low-temperature impact performance of the weld cladding metal after welding, meeting the high comprehensive performance requirements of cryogenic liquefied gas transport components, and is particularly suitable for the manufacture of cryogenic liquefied gas transport components. Detailed Implementation

[0050] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.

[0051] The main components of the iron-nickel alloy welding wires in Examples 1-6 are shown in Table 1, with the balance being Fe and unavoidable impurities.

[0052] Based on the process parameters shown in Table 2, the manufacturing method of the iron-nickel alloy welding wire in Examples 1-6 includes the following steps:

[0053] Smelting; smelting according to the above-mentioned composition of iron-nickel alloy welding wire;

[0054] Forging involves heating the smelted ingot to 1000~1200℃ and holding it for 60~180 minutes, then forging it into a forging billet.

[0055] Hot rolling involves heating the forged billet before rolling, controlling the heating temperature at 1000~1200℃, holding the temperature for 60~180min, and then hot rolling it into a coil.

[0056] Wire drawing involves drawing coiled wire into iron-nickel alloy welding wire. The product performance is shown in Table 3.

[0057] The main components of the iron-nickel alloy welding wires in Comparative Examples 1-4 are shown in Table 1, with the balance being Fe and unavoidable impurities;

[0058] Comparative Examples 1-4 adopted the manufacturing method in the examples, and the process parameters are shown in Table 2. The performance of the final iron-nickel alloy welding wire is shown in Table 3.

[0059] Table 1 Chemical composition (wt%) of iron-nickel alloy welding wire

[0060]

[0061] Table 2 Manufacturing process parameters

[0062]

[0063] Table 3 Performance of Iron-Nickel Alloy Welding Wire

[0064]

[0065] As shown in Tables 1, 2, and 3, the iron-nickel alloy welding wires obtained using the manufacturing method of this invention in Examples 1-6 have a coefficient of thermal expansion of 1.2 × 10⁻⁶ between -180°C and 0°C. -6 ~1.7×10 -6 m / m / ℃, the V-notch impact toughness of the cladding metal after welding with iron-nickel alloy welding wire at -196℃ is 170~180 J / cm. 2 Compared with the iron-nickel alloy welding wires of Comparative Examples 1-4, the present invention, through composition design and improved manufacturing method, can ensure the thermal expansion performance of the iron-nickel alloy welding wire and greatly improve the low-temperature impact performance of the cladding metal after welding at -196℃.

[0066] In Comparative Example 1, the iron-nickel alloy had excessively high Al and Si content, and the heating temperature before hot rolling was too low. This resulted in poor V-shaped impact toughness of the weld metal after welding at -196℃, reaching only 71 J / cm². 2 The low-temperature impact performance of the cladding metal after welding with the iron-nickel alloy welding wire in the example is far lower than that of the example, and it does not meet the requirements of the cryogenic liquefied gas transport component.

[0067] In Comparative Example 2, the La+Ce content and Si value of the iron-nickel alloy were too high, and the forging heating temperature was controlled too high during manufacturing. This resulted in poor V-shaped impact toughness of the weld metal after welding at a low temperature of -196℃, reaching only 69 J / cm. 2 The low-temperature impact performance of the cladding metal after welding with the iron-nickel alloy welding wire in the example is far lower than that of the example, and it does not meet the requirements of the cryogenic liquefied gas transport component.

[0068] In Comparative Example 3, the iron-nickel alloy had excessively high Mg and S1 content, and the heating temperature before hot rolling was too low. This resulted in poor V-shaped impact toughness of the weld metal after welding at -196℃, reaching only 76 J / cm². 2 The low-temperature impact performance is far lower than that of the cladding metal after welding with the iron-nickel alloy welding wires in Examples 1-6, and does not meet the requirements of cryogenic liquefied gas transport components.

[0069] In Comparative Example 4, the iron-nickel alloy had an excessively high carbon content and an excessively low Si value. Furthermore, the forging heating temperature was controlled too low during manufacturing. This resulted in poor V-shaped impact toughness of the weld metal after welding at -196℃, reaching only 59 J / cm². 2 The low-temperature impact performance of the cladding metal after welding with the iron-nickel alloy welding wire in Example 1 is far lower than that of the iron-nickel alloy welding wire in Example 1, and it does not meet the requirements of the cryogenic liquefied gas transport assembly.

[0070] In summary, the iron-nickel alloy welding wire manufactured by the method of the present invention has a coefficient of thermal expansion of (1.0~2.0)×10⁻¹⁰ between -180℃ and 0℃. -6 m / m / ℃, the V-shaped impact test result of the weld cladding metal after welding using this iron-nickel alloy welding wire at -196℃ is ≥150Jcm. -2 This invention ensures the low expansion performance of the iron-nickel alloy welding wire and improves the low-temperature impact performance of the weld cladding metal after welding, meeting the high comprehensive performance requirements of cryogenic liquefied gas transport components, and is particularly suitable for the manufacture of cryogenic liquefied gas transport components.

[0071] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A high-performance iron-nickel alloy welding wire with excellent low-temperature performance, characterized in that: Its chemical composition by weight percentage is as follows: 34.5%≤Ni≤37.5%, 0.040%≤C≤0.080%, 0.01%≤Si≤0.30%, 0.1%≤Mn≤0.6%, P≤0.0030%, S≤0.0015%, O≤0.0030%, N≤0.0020%, 0.0010%≤Mg≤0.0040%, 0.0001%≤Al≤0.0025%, V≤0.0020%, Ti≤0.0020%, Nb≤0.0020%, 0.0001%≤Ca≤0.0020%, B≤0.0010%, 0.0001%≤La+Ce≤0.0020%, with the balance being Fe and unavoidable impurities; The weight percentage of the chemical composition of the iron-nickel alloy welding wire also satisfies the following formula: 0≤S1≤0.010%； S1=(La+Ce)×2+C / 20+Al / 3×2+Mg×2+Ca+V / 3+Ti / 6+Nb / 6-O×3-N×3.

2. The iron-nickel alloy welding wire with excellent low-temperature performance according to claim 1, characterized in that: 0.002%≤S1≤0.009%。 3. The iron-nickel alloy welding wire with excellent low-temperature performance according to claim 1, characterized in that: 0.18%≤Mn≤0.6%, 0.0008%≤Al≤0.0020%, 0.0004%≤La+Ce≤0.0018%.

4. The iron-nickel alloy welding wire with excellent low-temperature performance according to claim 1, characterized in that: The coefficient of thermal expansion of the iron-nickel alloy welding wire between -180℃ and 0℃ is (1.0~2.0)×10⁻¹⁰. -6 m / m / ℃.

5. The iron-nickel alloy welding wire with excellent low-temperature performance according to claim 4, characterized in that: The coefficient of thermal expansion of the iron-nickel alloy welding wire between -180℃ and 0℃ is (1.2~1.7)×10⁻¹⁰. -6 m / m / ℃.

6. The iron-nickel alloy welding wire with excellent low-temperature performance according to claim 1, characterized in that: The weld cladding metal after welding with the iron-nickel alloy welding wire exhibits a V-shaped impact toughness ≥150 J / cm² at -196℃. -2 .

7. The iron-nickel alloy welding wire with excellent low-temperature performance according to claim 6, characterized in that: The weld cladding metal after welding with the iron-nickel alloy welding wire exhibits a V-shaped impact toughness of 170~180 J / cm² at -196℃. -2 .

8. A method for manufacturing an iron-nickel alloy welding wire with excellent low-temperature performance as described in any one of claims 1 to 7, characterized in that: Includes the following steps: Smelting; Forging involves heating the smelted ingot to 1000~1200℃ and holding it for 60~180 minutes, then forging it into a forging billet. Hot rolling involves heating the forged billet before rolling, controlling the heating temperature at 1000~1200℃, holding the temperature for 60~180min, and then hot rolling it into a coil. Wire drawing involves drawing coiled wire into iron-nickel alloy welding wire.

9. The method for manufacturing the iron-nickel alloy welding wire with excellent low-temperature performance according to claim 8, characterized in that: The smelting process employs electric furnace, electric furnace + electroslag remelting, vacuum induction + electroslag remelting, vacuum induction + vacuum self-consumption smelting, or vacuum induction + electroslag remelting + vacuum self-consumption smelting methods.

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