High-corrosion-resistant submerged arc welding material and application thereof

Abstract

The application belongs to the field of corrosion-resistant steel welding materials for railway vehicles, and particularly relates to a high-corrosion-resistance submerged arc welding material and application thereof. The application provides a high-corrosion-resistance submerged arc welding material, which comprises the following elements in percentage by mass: C: 0-0.04, Si: 0.15-0.30, Mn: 0.85-1.10, Cr: 2.10-2.60, Ni: 1.85-2.30, Cu: 0.14-0.30, Ti: 0.015-0.030, Mo: 0.05-0.18, Sn: 0.020-0.040, Nb: 0-0.025, Ca: 0-0.015, Ce: 0.020-0.040, O: 0.003-0.007, N: 0.004-0.010, and the balance of Fe and other inevitable impurities.

Description

Technical Field

[0001] This invention belongs to the field of corrosion-resistant steel welding materials for railway vehicles, specifically relating to a high corrosion-resistant submerged arc welding material and its application. Background Technology

[0002] Weathering steel, a type of steel with excellent corrosion resistance, has been popular since the mid-20th century and has been widely used in construction, bridges, and railways. Especially in the railway sector, weathering steel has become an indispensable material for railway freight cars due to its unique properties. In recent years, as my country's railway freight cars have moved towards higher axle loads, heavier loads, and higher corrosion resistance, the weathering steel used in railway vehicles has gradually shifted from the traditional 09CuPCrNi and O450NQR1 steels to the highly corrosion-resistant Q350EWR1-Q450EWR1 steels. The specific application of this series of high corrosion-resistant steels in railway freight cars is mainly in welded structural components. Because railway cars must withstand dynamic loads and have high requirements for crack resistance, solid welding wire is generally used, especially submerged arc welding solid welding wire, which is widely used in thick-gauge flat butt joints or ship-mounted corner joints. To ensure the corrosion resistance of the weld metal matches that of the base metal, this type of submerged arc welding wire generally uses the same alloy system as Q350EWR1-Q450EWR1 steel. A high proportion of Cr is often added to the welding wire, which results in a large amount of side-plate ferrite and coarse M / A components in the weld, leading to lower impact toughness. Reducing the Cr content of the welding wire improves the impact toughness, but the corrosion resistance still cannot match that of the base metal. Existing solid submerged arc welding wires for Q350EWR1-Q450EWR1 steel suffer from insufficient weld toughness or corrosion resistance. Therefore, it is necessary to redesign and optimize the composition system of the welding wire to achieve a weld that balances high corrosion resistance and excellent impact toughness. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a high corrosion-resistant submerged arc welding material comprising the following elements by mass percentage: C: 0-0.04, Si: 0.15-0.30, Mn: 0.85-1.10, Cr: 2.10-2.60, Ni: 1.85-2.30, Cu: 0.14-0.30, Ti: 0.015-0.030, Mo: 0.05-0.18, Sn: 0.020-0.040, Nb: 0-0.025, Ca: 0-0.015, Ce: 0.020-0.040, O: 0.003-0.007, N: 0.004-0.010, with the balance being Fe and other unavoidable impurities.

[0004] The present invention also provides a welding wire comprising the above-mentioned welding materials.

[0005] Furthermore, the weight percentages of Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O, and N in the welding wire satisfy the following: 0.07≤λ≤0.17, 2.8≤τ≤4.0, where: λ=(1.58O+N) / (Ti+1.5Ca+2.0Ce+0.7Sn), τ=(3Ni+Mo+1.5Cr+Si+2Cu+6Sn) / (Ni+8Mo+3Sn+7Nb).

[0006] Furthermore, the diameter of the welding wire is 3.95 mm.

[0007] Furthermore, the copper plating thickness of the welding wire is 0.14-0.18 μm.

[0008] The present invention also provides the application of the above-mentioned welding materials in the welding of railway vehicles.

[0009] The present invention has the following beneficial effects:

[0010] This invention provides a high corrosion-resistant submerged arc welding wire for railway vehicles that combines excellent corrosion resistance and low-temperature toughness of the weld. Its chemical composition, by mass percentage, includes C: 0-0.04%, Si: 0.15-0.30%, Mn: 0.85-1.10%, Cr: 2.10-2.60%, Ni: 1.85-2.30%, Cu: 0.14-0.30%, Ti: 0.015-0.030%, Mo: 0.05-0.18%, Sn: 0.020-0.040%, Nb: 0-0.025%, Ca: 0-0.015%, Ce: 0.020-0.040%, O: 0.003-0.007%, N: 0.004-0.010, and the balance being Fe and other unavoidable impurities. The chemical composition of Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O, and N in the welding wire, calculated by weight percentage, satisfies the following conditions: 0.07 ≤ λ ≤ 0.17, 2.8 ≤ τ ≤ 4.0, where λ = (1.58O + N) / (Ti + 1.5Ca + 2.0Ce + 0.7Sn) and τ = (3Ni + Mo + 1.5Cr + Si + 2Cu + 6Sn) / (Ni + 8Mo + 3Sn + 7Nb). This invention employs a Ni-Cr-Cu-Mo-Sn alloy system, effectively ensuring the stability and corrosion resistance of the weld rust layer. By adjusting the λ range, the morphology, size, and composition of inclusions are effectively controlled, fully utilizing the inclusions as nucleation sites for acicular ferrite. Based on the control of λ, further control of the τ range achieves a balance between excellent corrosion resistance and low-temperature toughness in the weld. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 The images show a comparison between actual welding photos and post-weld inclusions of the CO2 gas shielded welding wire provided by the present invention and CO2 gas shielded welding photos and post-weld inclusions of the welding wire provided in the comparative example. In the images, (a1) is an actual welding photo of the CO2 gas shielded welding wire described in Example 2, (a2) is a picture of post-weld inclusions of the CO2 gas shielded welding wire described in Example 2; (b1) is a CO2 gas shielded welding photo of the welding wire described in Comparative Example 1, and (b2) is a picture of post-weld inclusions of the welding wire described in Comparative Example 1.

[0013] Figure 2 The images provided by this invention are microstructure scans of the weld metal after CO2 gas shielded welding wire and microstructure scans of the weld metal after CO2 gas shielded welding wire provided in the comparative example. Among them, (a) is the microstructure scan of the weld metal after CO2 gas shielded welding wire provided in Example 4, and (b) is the microstructure scan of the weld metal after CO2 gas shielded welding wire provided in Comparative Example 2.

[0014] Figure 3 The images provided by this invention are morphological images of the rust layer on the surface of the weld metal after 48 hours of accelerated corrosion immersion in CO2 gas shielded welding wire, and morphological images of the rust layer on the surface of the weld metal after 48 hours of accelerated corrosion immersion in CO2 gas shielded welding wire, provided in the comparative example. Among them, (a1) and (a2) are morphological images of the rust layer on the surface of the weld metal after 48 hours of accelerated corrosion immersion in CO2 gas shielded welding wire according to Example 5, and (b1) and (b2) are morphological images of the rust layer on the surface of the weld metal after 48 hours of accelerated corrosion immersion in CO2 gas shielded welding wire according to Comparative Example 3. Detailed Implementation

[0015] Various exemplary embodiments of the present invention are now described in detail. Unless otherwise specified, the methods used in the embodiments are conventional methods, and the reagents used are commercially available reagents or reagents prepared using conventional methods. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0016] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0017] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0018] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0019] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0020] Examples 1-7 and Comparative Examples 1-3

[0021] This invention provides a high corrosion-resistant submerged arc welding wire for railway vehicles that combines excellent corrosion resistance and low-temperature toughness of the weld. Its chemical composition, by mass percentage, includes C: 0-0.04%, Si: 0.15-0.30%, Mn: 0.85-1.10%, Cr: 2.10-2.60%, Ni: 1.85-2.30%, Cu: 0.14-0.30%, Ti: 0.015-0.030%, Mo: 0.05-0.18%, Sn: 0.020-0.040%, Nb: 0-0.025%, Ca: 0-0.015%, Ce: 0.020-0.040%, O: 0.003-0.007%, N: 0.004-0.010, and the balance being Fe and other unavoidable impurities.

[0022] The chemical composition of Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O and N in the welding wire, calculated by weight percentage, satisfies the following: 0.07≤λ≤0.17, 2.8≤τ≤4.0, where λ=(1.58O+N) / (Ti+1.5Ca+2.0Ce+0.7Sn), and τ=(3Ni+Mo+1.5Cr+Si+2Cu+6Sn) / (Ni+8Mo+3Sn+7Nb).

[0023] The submerged arc welding wire provided by this invention contains 0% to 0.04% C by mass percentage. Adding a certain amount of C element to the welding wire is beneficial for the rolling of the welding wire rod, increases the stiffness of the welding wire, and also helps to improve the strength of the weld. However, when the C content is too high, it will lead to a significant increase in carbon equivalent, reduce plasticity, and also increase the crack sensitivity of the weld joint.

[0024] The submerged arc welding wire provided by this invention comprises 0.15% to 0.30% Si by weight. Si can form a Si-rich protective film on the weld metal surface, refine α-FeOOH, reduce the corrosion rate, and improve corrosion resistance. Simultaneously, Si, as one of the main alloying elements in the weld, has a strong deoxidizing effect and improves the fluidity of the molten pool. However, excessive Si content can lead to the appearance of coarse side-plate ferrite and M / A components in the weld microstructure. Considering that the submerged arc welding flux will transfer Si into the weld, the Si content of the submerged arc welding wire is designed to be 0.15% to 0.30%.

[0025] The submerged arc welding wire provided by this invention comprises Mn: 0.85-1.10 by weight percentage. Mn is also a major deoxidizer in the welding wire, which is beneficial for its combined action with Si to reduce the oxygen content of the weld metal, increase the strength and crack resistance of the weld metal, and Mn also has a desulfurization effect. However, as the Mn content increases, it will cause severe segregation, which will degrade the drawing performance and processing performance of the welding wire.

[0026] The submerged arc welding wire provided by this invention contains Cr: 2.10-2.60 by weight percentage. During the corrosion process of steel, Cr can accumulate on the surface of the matrix, forming iron-chromium multi-element alloy oxides, which fill the microcracks and voids in the rust layer, increase the density of the rust layer, and improve atmospheric corrosion resistance. However, when its content is high, it will reduce the fluidity of the molten pool, which is not conducive to the removal of gas and inclusions in the weld. At the same time, the increase in Cr content in the weld will cause the increase and coarsening of the M / A components, reducing the toughness of the weld.

[0027] By weight percentage, the submerged arc welding wire provided by this invention comprises 1.85% to 2.30% Ni. The addition of Ni refines the crystallization of the rust layer, makes it easier for γ-FeOOH to transform into stable α-FeOOH, inhibits the intrusion of corrosive substances, and improves the atmospheric corrosion resistance of steel. Ni can refine ferrite grains and improve the low-temperature impact toughness of steel; however, excessive Ni content can also cause segregation and increase the viscosity of the weld pool, reducing the drawability and metallurgical quality of the welding wire.

[0028] The submerged arc welding wire provided by this invention comprises 0.14% to 0.30% Cu by weight. During the corrosion process of steel, Cu accumulates on the surface of the weld metal to form a dense oxide layer, which can make the inner rust layer grains finer and denser. Furthermore, Cu is a precipitation strengthening element, which can improve the strength and toughness of the weld within a certain range. However, excessive Cu content will make the welding slag viscous and difficult to clean, increasing the tendency for hot cracking in the weld. Considering that copper plating on the surface of the welding wire will also increase the Cu content of the weld, the Cu content added to the welding wire steel is 0.14% to 0.30%.

[0029] The submerged arc welding wire provided by this invention comprises 0.015% to 0.030% Ti by mass percentage. Ti is chemically active and has a strong deoxidizing effect, which can effectively protect the transition of Si and Mn to the weld. Its oxide enrichment on the surface of inclusions can effectively play the role of ferrite nucleation sites. However, excessive Ti content will significantly coarsen the size of inclusions in the weld, which will not only increase crack susceptibility but also cause serious pitting corrosion problems.

[0030] The submerged arc welding wire provided by this invention comprises 0.05% to 0.18% Mo by weight. Adding Mo to the weld not only forms molybdates, increasing the density of the rust layer and improving the steel's resistance to atmospheric corrosion, but also significantly reduces the phase transformation temperature and inhibits the formation of coarse, blocky ferrite. However, excessive Mo content can lead to the formation of enriched regions near grain boundaries, promoting the formation of lamellar and network-like Mo phases near the grain boundaries, reducing the continuity of the matrix, and decreasing the strength and toughness of the weld.

[0031] The submerged arc welding wire provided by this invention comprises Sn: 0.020% to 0.040% by mass percentage. Sn is generally considered to be a harmful element in steel, which tends to agglomerate at columnar grain boundaries, reducing the low-temperature toughness of the weld. However, Sn can significantly improve the corrosion resistance of the matrix under industrial atmospheric conditions. In particular, Sn precipitates on the surface of the weld metal and is oxidized to SnO2, which can improve corrosion resistance. Moreover, Sn can react with O and N in steel to form chemicals that adhere to the surface of inclusions, playing the role of nucleation sites for acicular ferrite. Taking all factors into consideration, the Sn content in the weld is controlled within the range of 0.020% to 0.040%.

[0032] The submerged arc welding wire provided by this invention contains Nb: 0% to 0.025% by mass percentage. Nb can combine with elements such as N and C to purify the weld. Nb(C,N) particles can precipitate at austenite grain boundaries, pin the grain boundaries, inhibit the growth of austenite, and play a role in refining the weld structure. However, excessive Nb content will reduce weldability and increase the crack sensitivity of the weld joint.

[0033] The submerged arc welding wire provided by this invention comprises 0% to 0.015% Ca by weight. Ca can improve the fluidity of the weld pool, enhance the transition of Si and Mn alloying elements, and reduce the impact of residual rust on the steel plate surface on welding processability and weld mechanical properties. Simultaneously, the addition of Ca can react with O in the steel, forming inclusions that act as heterogeneous nucleation sites for ferrite. However, an increase in Ca content leads to a more intense reaction in the submerged arc welding pool, which is detrimental to obtaining good weld formation.

[0034] The submerged arc welding wire provided by this invention contains 0.020% to 0.040% Ce by weight. Ce can improve the fluidity of the weld pool, enhance the transition of Si and Mn alloying elements, and also refine and disperse inclusions, which is beneficial for obtaining fine inclusions in the weld. At the same time, Ce can form inclusions with S, O, and N elements, and also play a role in heterogeneous nucleation of ferrite. However, welding wire steel with high Ce content is more difficult to smelt, and excessive Ce content during welding is not conducive to obtaining excellent welding metallurgical quality.

[0035] The submerged arc welding wire provided by this invention comprises O: 0.003% to 0.007% and N: 0.004% to 0.010% by mass percentage. This invention controls the N and O in the welding wire steel to regulate the welding metallurgical quality and weld inclusions. However, excessive O and N content will cause high weld porosity and loss of alloying elements.

[0036] The submerged arc welding wire provided by this invention, by weight percentage, also includes the balance Fe. In this invention, Fe is a matrix element.

[0037] In this invention, the chemical composition of Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O and N in the welding wire, calculated by weight percentage, satisfies the following: 0.07≤λ≤0.17, 2.8≤τ≤4.0, where λ=(1.58O+N) / (Ti+1.5Ca+2.0Ce+0.7Sn), and τ=(3Ni+Mo+1.5Cr+Si+2Cu+6Sn) / (Ni+8Mo+3Sn+7Nb).

[0038] To ensure that the corrosion resistance of the welding wire of this invention matches that of high corrosion-resistant steel for railway vehicles of grades Q350EWR1-Q450EWR1, a Ni-Cr-Cu-Mo-Sn alloy system is adopted. However, the addition of a large amount of Ni and Cr to this alloy system can significantly increase the viscosity of the weld pool and reduce its fluidity, resulting in large inclusions in the weld. These large inclusions not only become crack initiation points, increasing crack sensitivity, but also reduce the probability of them serving as nucleation sites for acicular ferrite, leading to the formation of granular bainite and large blocky ferrite structures in the weld. Consequently, it is difficult to achieve both excellent corrosion resistance and low-temperature toughness in the weld. This invention controls the composition of Ti, Ca, Ce, Sn, O, and N to conform to the range of λ. On the one hand, it interacts with Si in the steel to improve the fluidity of the molten pool. On the other hand, it controls the morphology, size, and composition of inclusions, so that the silicate inclusions are dispersed and transformed into spherical shapes. Furthermore, oxides or nitrides of Ti, Ca, Ce, and Sn adhere to the surface of the silicate inclusions, which can effectively act as nucleation sites for acicular ferrite.

[0039] Based on the control of λ, the range of Ni, Mo, Cr, Cu, Si, Nb, Ti and Sn conforming to τ is further controlled. The matching of elements that mainly play the role of weld corrosion resistance and elements that play the role of refining weld microstructure is controlled. While improving the rust layer structure and density and improving the corrosion resistance of the weld, the microstructure of needle-like ferrite formed in the weld is refined, thereby achieving a balance between weld corrosion resistance and low-temperature toughness.

[0040] The present invention also provides a method for preparing the submerged arc welding wire described in the above technical solution, comprising the following steps:

[0041] (1) Smelting and casting of welding wire steel according to the above-mentioned welding wire composition;

[0042] (2) Forge the billet obtained in step (1) at a forging temperature of 1000℃-1050℃;

[0043] (3) The forgings obtained in step (2) are rolled into wire rods at a rolling temperature of 830-880℃; the wire rod diameter...

[0044] (4) The wire rod obtained in step (3) is subjected to slow cooling treatment. The slow cooling temperature range is 740-490℃ and the slow cooling time is 10min.

[0045] (5) Perform a drawing and diameter reduction process on the wire rod obtained in step (4) to reduce the diameter of the wire rod to the required diameter.

[0046] (6) The reduced diameter wire obtained in step (5) is copper-plated to obtain the finished welding wire with a copper plating layer thickness of 0.14-0.18μm.

[0047] The composition system provided by this invention is easy to smelt and prepare, and the preparation process of the welding wire is simple and easy to control. The technical solution of this invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0048] Seven heats of welding wire steel according to the embodiments of the present invention and three heats of welding wire steel according to the comparative examples were produced in a 75kg vacuum induction furnace. The elemental composition of the welding wire steel according to the embodiments of the present invention meets the requirements of the present invention. The welding wire steels of the embodiments and the comparative examples were melted and cast sequentially according to a certain elemental composition ratio to obtain as-cast alloy billets. The composition of the welding wire steels of the embodiments and the comparative examples was analyzed according to GB / T4336 "Spark Source Atomic Emission Spectroscopy Analysis Method (Conventional Method) for Carbon Steel and Medium and Low Alloy Steels". The specific chemical composition is shown in Table 1.

[0049] Table 1. Chemical composition (wt.%, balance Fe) of welding wire steel in Examples 1-7 and Comparative Examples 1-3

[0050] serial number C Si Mn P S Cr Ni Cu Mo Ti Ca Sn Nb Ce B O N λ τ Example 1 0.03 0.18 0.87 0.009 0.004 2.25 1.95 0.17 0.11 0.017 0.012 0.024 0.015 0.025 0 0.005 0.008 0.16 3.33 Example 2 0.04 0.28 1.02 0.012 0.003 2.19 2.16 0.23 0.09 0.025 0.008 0.036 0 0.038 0 0.004 0.005 0.08 3.62 Example 3 0.03 0.19 0.93 0.008 0.004 2.54 1.97 0.26 0.07 0.021 0 0.031 0.02 0.036 0 0.006 0.009 0.16 3.87 Example 4 0.02 0.22 0.95 0.013 0.004 2.43 1.89 0.21 0.12 0.019 0.01 0.027 0.017 0.027 0 0.003 0.007 0.11 3.36 Example 5 0.04 0.27 0.99 0.009 0.003 2.36 2.26 0.19 0.16 0.027 0.005 0.029 0.021 0.031 0 0.006 0.006 0.13 3.00 Example 6 0.03 0.16 1.06 0.010 0.003 2.17 2.17 0.22 0.07 0.024 0 0.037 0 0.035 0 0.004 0.007 0.11 3.75 Example 7 0.03 0.25 0.89 0.011 0.004 2.47 2.11 0.19 0.12 0.026 0.013 0.032 0.01 0.028 0 0.006 0.008 0.14 3.39 Comparative Example 1 0.03 0.08 0.50 0.009 0.003 1.75 4.20 0.20 0 0.05 0 0 0 0 0.002 0.004 0.006 0.25 3.74 Comparative Example 2 0.04 0.40 0.50 0.010 0.004 1.35 3.40 0.15 0 0.03 0 0 0 0 0.005 0.005 0.007 0.50 3.80 Comparative Example 3 0.05 0.20 0.60 0.009 0.004 0.30 1.0 0.30 0.50 0.05 0 0 0 0 - 0.005 0.007 0.30 0.95

[0051] Welding wires were prepared for the welding wire steels of Examples 1-7 and Comparative Examples 1-3. The specific preparation process for each welding wire steel is summarized in Table 2. The welding wire steels of the Examples and Comparative Examples prepared using this process did not experience wire breakage during the drawing process. The copper plating thickness on the surface of the welding wire was uniform, and no peeling or cracking issues occurred.

[0052] Table 2. Main process parameters for preparing submerged arc welding wire in Examples 1-7 and Comparative Examples 1-3

[0053]

[0054]

[0055] Performance testing

[0056] Welding tests were conducted on typical butt joints of the welding wires prepared in Examples 1-7 and Comparative Examples 1-3. The specific welding process parameters are shown in Table 3. The test plates used for welding were made of Q450EWR1 corrosion-resistant steel with a thickness of 24mm, a yield strength of 474MPa, a tensile strength of 594MPa, an elongation of 22%, and a low-temperature impact resistance of -40℃ of 201J.

[0057] Table 3. Submerged arc welding process parameters for Examples 1-7 and Comparative Examples 1-3

[0058]

[0059] During actual welding, the weld surface appearance of the welding wires in the comparative examples and embodiments was observed. The weld morphology of Example 2 and Comparative Example 1 are shown in the figures below. Figure 1 (a1) and Figure 1 (b1) The results show that the welding wire in the embodiment exhibits smooth submerged arc welding during actual welding, with uniform weld bead distribution and good weld formation. In contrast, the welding wire in the comparative example suffers from arc breakage during welding, severe undercut, and poor weld formation. After welding, all welds were subjected to flaw detection. Macroscopic cross-sections of the joints were taken from the defect-free areas of the embodiment and the comparative example to detect the weld composition. The results are shown in Table 4.

[0060] Table 4. Chemical composition (wt.%, balance Fe) of the weld metal after submerged arc welding of Examples 1-7 and Comparative Examples 1-3.

[0061]

[0062]

[0063] After the composition analysis was completed, the macroscopic cross-sections of the joints in the examples and comparative examples were sanded. Inclusions in the welds were observed and analyzed under a metallographic microscope. The inclusion morphology of Examples 2 and Comparative Example 1 is shown below. Figure 1 (a2) and Figure 1 (b2) The statistical results of the inclusion size distribution are shown in Table 5. Through the inclusion morphology and statistical results, it can be found that the average size of the inclusions in the examples is small, mostly between 0.2-1.0 μm, and is in a diffuse distribution state. However, the inclusions in the weld of the comparative example show an aggregation phenomenon, with a larger average size and a significantly increased proportion of inclusions of 1.8-2.2 μm.

[0064] Table 5. Size distribution of inclusions in submerged arc welds of Examples 1-7 and Comparative Examples 1-3.

[0065]

[0066]

[0067] Weld samples from Examples 1-7 and Comparative Examples 1-3 that passed flaw detection were taken, and the mechanical properties of the weld metal were tested. The tensile properties of the weld metal were sampled and tested according to GB / T 228.1 standard, and the impact properties were sampled and tested according to GB / T 2650 standard. Three impact samples were taken for each sample to reduce error. The results of the mechanical property tests are shown in Table 6. The results show that in this example, the weld metal with different fluxes exhibits excellent weld strength and toughness. However, in the comparative examples, although the weld metal strength matched the base metal with different fluxes, the impact performance was reduced. EBSD characterization of the weld microstructure of Examples 4 and Comparative Example 2 revealed that, as... Figure 2 In the example, the weld has a large number of acicular ferrite structures, and its grain boundaries are mostly large-angle grain boundaries. The high density of large-angle grain boundaries plays a role in improving impact toughness. In contrast, the weld in the comparative example is mainly composed of blocky ferrite and granular bainite, and its large-angle grain boundary density is relatively low, thus obtaining relatively low impact toughness.

[0068] Table 6 shows the mechanical property test results of the submerged arc weld metals after Examples 1-7 and Comparative Examples 1-3.

[0069]

[0070] Weld samples from Examples 1-7 and Comparative Examples 1-3 that passed flaw detection were taken, and the relative corrosion resistance of the weld metal to the base metal was tested. The tests were conducted according to TB 2374-2008 "Atmospheric Corrosion Resistant Steel and Stainless Steel Welding Materials for Railway Vehicles" and TB 2375-1993 "Cyclic Immersion Corrosion Test Method for Weathering Steel for Railways". A 0.01 mol / L NaHSO3 solution was used to simulate the industrial atmospheric environment. Accelerated corrosion tests were conducted on the Q450EWR1 base metal and weld metal for 120 hours in a cyclic immersion accelerated corrosion test chamber. The relative corrosion rate of the base metal and the weld metal of the examples and comparative examples (relative corrosion rate = |(base metal weight loss - weld metal weight loss) / base metal weight loss × 100%) was calculated to evaluate the atmospheric corrosion resistance of the base metal and weld metal. The test results after 120 hours are shown in Table 6. The results showed that the submerged arc weld metals of the examples all had a relative corrosion rate of less than 9.4% with the Q450EWR1 base metal, meeting the standard requirement of less than 10%. However, the relative corrosion rate of the welding wire in the comparative example was higher than 14%, indicating a significant difference in corrosion resistance compared to the base metal, failing to achieve the same level of corrosion resistance. Furthermore, the accelerated corrosion plates used for 60h and 96h of immersion in Examples 6 and 3 were observed. The corrosion pits on the surface of the plates from the examples were shallower, while the plates from the comparative example showed numerous obvious depressions, indicating that the corrosive liquid had a greater corrosive effect on the welds of the comparative example, which is detrimental to obtaining excellent corrosion resistance.

[0071] Table 7 shows the comparison results of corrosion weight loss and base metal in the perimeter immersion test of submerged arc welded weld metals in Examples 1-7 and Comparative Examples 1-3.

[0072]

[0073] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A welding wire, characterized in that, The elements include the following elements in mass percentage: C: 0-0.04, Si: 0.15-0.30, Mn: 0.85-1.10, Cr: 2.10-2.60, Ni: 1.85~2.30, Cu: 0.14-0.30, Ti: 0.015~0.030, Mo: 0.05-0.18, Sn: 0.020-0.040, Nb: 0-0.025, Ca: 0-0.015, Ce: 0.020-0.040, O: 0.003-0.007, N: 0.004-0.010, with the balance being Fe and other unavoidable impurities; the weight percentages of Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O, and N in the welding wire satisfy the following: 0.07≤λ≤0.17, 2.8≤τ≤4.0, where: λ= (1.58 O+N) / (Ti+1.5 Ca+2.0 Ce+0.7 Sn), τ= (3Ni+Mo+1.5Cr+Si+2Cu+6Sn) / (Ni+8Mo+3Sn+7Nb).

2. The welding wire according to claim 1, characterized in that, The diameter of the welding wire is 3.95 mm.

3. The welding wire according to claim 1, characterized in that, The copper plating thickness of the welding wire is 0.14-0.18 μm.

4. The application of the welding wire as described in claim 1 in the welding of railway vehicles.

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