A Highly Corrosion-Resistant CO2 Gas Shielded Welding Material and Its Application

Abstract

The application belongs to the field of corrosion-resistant steel welding materials for railway vehicles, and particularly relates to a high-corrosion-resistance CO2 gas shielded welding material and application thereof. The application provides a high-corrosion-resistance CO2 gas shielded welding material, which comprises the following elements in percentage by mass: C: 0-0.04, Si: 0.85-1.10, Mn: 0.90-1.15, Cr: 1.50-2.70, Ni: 2.10-2.40, Cu: 0.18-0.34, Ti: 0.035-0.055, Zr: 0.015-0.035, Ce: 0.035-0.055, V: 0.025-0.050, B: 0.0015-0.003, O: <=0.005, N: 0.003-0.009, 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 CO2 gas shielded welding material and its application. Background Technology

[0002] my country's railways have extended to various regions, and the environments and conditions for railway vehicle relocation are complex and demanding, requiring high-performance steel for railway vehicles. Simultaneously, with the development of railway vehicles towards heavy-load, high-speed, and lightweight designs, the comprehensive performance requirements for railway vehicle steel are even higher, demanding not only excellent corrosion resistance but also superior mechanical properties. Traditional railway vehicles are generally manufactured using 09CuPCrNi and O450NQR1 steels, but their poor corrosion resistance and short service life make it difficult to meet the demands of heavy-load, lightweight, and long-life railway vehicle development. Q350EWR1-Q450EWR1 grade railway vehicle steels offer superior corrosion resistance and high strength, and have been widely used in the railway vehicle steel field in recent years. In engineering applications, to ensure excellent crack resistance and low-temperature impact toughness, this series of steels commonly uses gas-shielded welding solid wire and submerged arc welding wire. Among these, argon-rich gas-shielded welding solid wire is the primary type, widely used in the welding of high corrosion-resistant steel fillet and butt joints. However, when splicing and welding components and welding joints in a vertical position, the welding parameters and actual operation are highly variable. Due to the small volume of the molten pool and the fast cooling rate during argon-rich gas shielded welding, the gas generated by the metallurgical reaction may not have enough time to overflow from the molten pool, resulting in porosity defects. In vertical welding, arc interruption is also prone to occur during argon-rich gas welding, resulting in poor weld continuity. CO2 gas shielded welding is less sensitive to changes in welding parameters, has high arc stability, and the gas is readily available and inexpensive, making it particularly suitable for vertical welding of components and splicing assembly. However, CO2 gas shielded welding involves a high oxidizing atmosphere, resulting in significant welding spatter. The weld often requires multiple grinding processes. Furthermore, the strong oxidizing atmosphere leads to severe loss of alloying elements. Existing solid welding wires used in CO2 gas welding produce a large amount of granular bainite and hard, brittle phases such as M / A components in the weld microstructure, significantly reducing the weld's mechanical properties, especially impact resistance. Corrosion resistance also decreases due to element loss. Therefore, CO2 gas shielded welding is rarely used in the railway vehicle industry, and research on related CO2 gas shielded welding solid welding wires is limited. Considering the needs of practical engineering and the advantages of CO2 gas shielded welding's good operability and low cost, it is necessary to develop a CO2 gas shielded welding solid welding wire specifically for Q350EWR1-Q450EWR1 steel, based on relevant metallurgical principles, with minimal welding spatter and low alloying element loss. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a high corrosion-resistant CO2 gas shielded welding material, comprising the following elements by mass percentage: C: 0-0.04, Si: 0.85-1.10, Mn: 0.90-1.15, Cr: 1.50-2.70, Ni: 2.10-2.40, Cu: 0.18-0.34, Ti: 0.035-0.055, Zr: 0.015-0.035, Ce: 0.035-0.055, V: 0.025-0.050, B: 0.0015-0.003, O: ≤0.005, N: 0.003-0.009, 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 chemical composition of the welding wire, calculated by weight percentage, satisfies 0.09≤σ≤0.17, 0.04≤ω≤0.12, where: σ=(Ti+2Zr+3Ce) / (Si+0.75Mn), ω=N / (B+2V).

[0006] The present invention also provides the application of the above-mentioned welding materials in the welding of railway vehicles.

[0007] The present invention has the following beneficial effects:

[0008] This invention provides a CO2 gas shielded welding wire and its welding method suitable for welding high corrosion-resistant steel for railway vehicles of grades Q350EWR1-Q450EWR1. The weld metal produced by this welding wire and welding process has an impact energy of over 65J at -40℃ and a relative corrosion rate of less than 8.1% compared with high corrosion-resistant steel. This invention can effectively solve the problems of large welding spatter and low corrosion resistance and impact toughness of welds when using existing welding wires for high corrosion-resistant steel for railway vehicles with CO2 gas shielded welding. Attached Figure Description

[0009] 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.

[0010] Figure 1The 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.

[0011] 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.

[0012] Figure 3 The images show the rust morphology of the weld metal sample after 48 hours of accelerated corrosion immersion in CO2 gas shielded welding wire provided by the present invention and the rust morphology of the weld metal sample after 48 hours of accelerated corrosion immersion in CO2 gas shielded welding wire provided by the comparative example. Among them, (a) is the rust morphology of the weld metal sample after 48 hours of accelerated corrosion immersion in CO2 gas shielded welding wire provided by Example 5, and (b) is the rust morphology of the weld metal sample after 48 hours of accelerated corrosion immersion in CO2 gas shielded welding wire provided by Comparative Example 3. Detailed Implementation

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] Examples 1-7 and Comparative Examples 1-3

[0019] This invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method. It is characterized by being made from the following chemical components in mass percentage (wt.%): C: 0-0.04, Si: 0.85-1.10, Mn: 0.90-1.15, Cr: 1.50-2.70, Ni: 2.10-2.40, Cu: 0.18-0.34, Ti: 0.035-0.055, Zr: 0.015-0.035, Ce: 0.035-0.055, V: 0.025-0.050, B: 0.0015-0.003, O: ≤0.005, N: 0.003-0.009, with the balance being Fe and other unavoidable impurities.

[0020] The present invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and a welding method thereof, which includes C by mass percentage: 0-0.04%. By adding C and controlling its content within the above range, the present invention can fully utilize the benefits of C in improving the processing performance of the welding wire and enhancing the strength and toughness of the weld, significantly reduce the generation of cracks during the wire drawing process, and avoid the formation of large-sized hard and brittle carbides in the weld.

[0021] This invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method, which contains Si by mass percentage: 0.85-1.10%. By adding Si and controlling its content within the above range, this invention can fully utilize Si's deoxidizing, corrosion-resistant, and molten pool viscosity characteristics. In CO2 gas-shielded welding, the oxidizing atmosphere is high, and a low Si content is not conducive to obtaining high weld pool fluidity and low oxygen content welds. Weld corrosion resistance increases significantly with increasing Si content, but excessive Si will dissolve into the weld, significantly increasing the quantity and size of ferrite and hard phase M / A components in the side strips.

[0022] The present invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method, which contains Mn by mass percentage: 0.9-1.15%. Mn in the welding wire can combine with Si to deoxidize the weld and reduce welding spatter, and can also remove S and FeO from the weld. However, when the Mn content is too high, the welding wire has higher stiffness, which is not conducive to actual welding.

[0023] The present invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method, which contains Cr by mass percentage: 1.50-2.70%. Increasing the Cr content in the weld will improve the density of the rust layer and increase its α-FeOOH content. When added in a certain amount, it can also play a role in solid solution strengthening. However, excessive Cr will increase the proportion of side strip ferrite and hard phase M / A components in the weld.

[0024] The present invention provides a high corrosion-resistant CO2 gas shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method. The wire contains Ni by mass percentage: 2.10-2.40%. Increasing the Ni content in the weld can not only increase corrosion resistance, but also refine ferrite grains and reduce the problem of low low-temperature toughness caused by high oxidizing atmosphere in CO2 gas shielded welding. However, if the Ni content is too high, it will cause segregation inside the wire rod and reduce the drawing performance. During the welding process, the excessive Ni content will increase the viscosity of the molten pool, which is not conducive to the discharge of pores and other defects, and is not conducive to obtaining good metallurgical quality.

[0025] This invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method. The wire contains 0.18–0.34% Cu by mass. During corrosion, Cu can accumulate on the surface of steel to form a dense oxide layer, while simultaneously making the internal rust layer finer and denser, preventing further corrosion. However, excessive Cu content increases the tendency for hot cracking in the weld. Considering that the welding wire developed in this invention has a copper plating layer, 0.1%–0.15% Cu will be transferred to the weld during welding. Therefore, the Cu content in the welding wire is 0.18–0.34%.

[0026] The present invention provides a high corrosion-resistant CO2 gas shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method. The wire contains Ti by mass percentage: 0.035-0.055%. Ti can reduce the welding spatter rate during welding, and it readily reacts with oxygen and nitrogen to generate inclusions or second-phase particles, playing a role in pinning the original austenitic grain boundaries, refining the grains, and acting as a ferrite nucleation site. However, excessive Ti content can easily lead to the appearance of large-sized inclusions in the weld, increasing the susceptibility to cracking.

[0027] The present invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method. The wire contains Zr by mass percentage: 0.015-0.035%. Adding Zr to the weld can increase the fluidity of the molten pool and significantly reduce the probability of hydrogen porosity. At the same time, the oxide generated by the reaction of Zr with oxygen can also serve as an effective nucleation site for acicular ferrite. However, excessive Zr content will significantly increase hardenability and promote the formation of bainite, thereby increasing the crack sensitivity of the weld.

[0028] The present invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method. The wire contains Ce by mass percentage: 0.035-0.055%. The addition of Ce to the weld is beneficial to the spheroidization of silicate inclusions and promotes their dispersion distribution, reducing crack sensitivity. At the same time, its enrichment on the surface of inclusions can also effectively play the role of acicular ferrite nucleation sites. However, the increase of Ce content will cause difficulties in the smelting of welding wire steel and increase the spatter rate during welding.

[0029] The present invention provides a high corrosion-resistant CO2 gas shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method. The wire contains V by mass percentage: 0.025-0.050%. It is generally believed that V dissolved in the weld metal will reduce weldability and increase the tendency to crack. However, if V exists in the form of precipitation and adheres to the surface of inclusions, it can significantly improve the nucleation of acicular ferrite and refine the microstructure of the weld.

[0030] The present invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method. The wire contains 0.0015-0.003% B by mass percentage. The B element is dissolved in the weld metal and can agglomerate at the grain boundaries, playing a role in inhibiting grain boundary migration and the formation of proeutectoid ferrite. The B element and N element precipitate and adhere to the surface of inclusions, which can also play the role of effective nucleation sites for ferrite. However, B is an element that significantly improves hardenability. When its content is too high, it will increase the susceptibility to cracking.

[0031] This invention provides a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method. The welding wire is required to contain O: ≤0.005 wt.% and N: 0.003-0.009 wt.% by mass percentage. The low oxygen content in the weld reduces the oxidizing atmosphere of CO2 gas-shielded welding and minimizes spatter. Controlling the amount of N allows the VN and BN particles formed by adding V and B to the welding wire to fully utilize their role as nucleation sites for acicular ferrite.

[0032] In this invention, a high corrosion-resistant CO2 gas shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method are provided. The mass percentages of Ti, Zr, Ce, Si, and Mn elements are controlled to conform to 0.09≤σ≤0.17, where σ=(Ti+2Zr+3Ce) / (Si+0.75Mn). In CO2 gas shielded welding, the oxidizing atmosphere is relatively high. Through the strong oxidizing effect of Ti, Zr, and Ce, the transition of Si and Mn to the weld is effectively protected, which plays a role in reducing welding spatter in CO2 gas shielded welding. At the same time, the proportional addition of Ti, Zr, Ce, Si, and Mn can control the morphology and size of inclusions with silicate as the core, so that the inclusions are spheroidized and more dispersed and refined in the weld, reducing crack sensitivity and reducing pitting corrosion problems.

[0033] In this invention, a high corrosion-resistant CO2 gas-shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method are described. The ratios of V, B, and N are controlled to conform to 0.04 ≤ ω ≤ 0.12, where ω = N / (B + 2V). In CO2 gas-shielded welding, to ensure the corrosion resistance of the weld metal matches that of the base metal, a large amount of elements such as Cr, Ni, and Cu are added. This results in a weld microstructure dominated by coarse blocky ferrite and granular bainite. (The last sentence appears to be incomplete and requires further context.) With the effect of 0.09≤σ≤0.17, we achieved a more dispersed and refined distribution of inclusions in the weld. However, within the bainitic ferrite transformation range, granular bainite nucleating at grain boundaries still dominates, rather than acicular ferrite nucleating on inclusions. By controlling 0.04≤ω≤0.12, we promoted the precipitation of VN and BN on the inclusion surface, reduced the mismatch between inclusions and acicular ferrite, promoted the nucleation of acicular ferrite, and achieved a significant refinement of the weld microstructure.

[0034] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes a high corrosion-resistant CO2 gas shielded welding wire for railway vehicles with excellent weld impact toughness and its welding method, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0035] 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.

[0036] Table 1. Chemical composition (wt.%, balance Fe) of welding wire steel in Examples 1-7 and Comparative Examples 1-3

[0037] serial number C Si Mn P S Cr Ni Cu Mo Ti Zr Ce B V Nb O N σ ω Example 1 0.03 1.06 1.02 0.010 0.004 1.89 2.15 0.23 - 0.038 0.017 0.041 0.0017 0.034 - 0.004 0.005 0.11 0.07 Example 2 0.02 0.95 1.07 0.009 0.005 2.06 2.33 0.30 - 0.041 0.020 0.039 0.0018 0.041 - 0.005 0.007 0.11 0.08 Example 3 0.04 0.99 0.99 0.010 0.004 2.53 2.19 0.22 - 0.047 0.031 0.051 0.0026 0.029 - 0.004 0.006 0.15 0.10 Example 4 0.03 0.91 0.96 0.008 0.005 2.16 2.24 0.19 - 0.050 0.027 0.048 0.0021 0.038 - 0.003 0.004 0.15 0.05 Example 5 0.04 1.06 1.13 0.009 0.004 1.67 2.11 0.32 - 0.039 0.029 0.036 0.0025 0.047 - 0.004 0.006 0.11 0.06 Example 6 0.03 0.88 1.05 0.011 0.003 2.43 2.36 0.24 - 0.052 0.031 0.047 0.0019 0.043 - 0.003 0.008 0.15 0.09 Example 7 0.04 0.97 0.95 0.007 0.005 2.37 2.25 0.28 - 0.045 0.019 0.045 0.0023 0.039 - 0.005 0.005 0.13 0.06 Comparative Example 1 0.07 0.55 0.81 0.009 0.005 1.35 4.08 0.21 - 0.08 - - - 0.03 - 0.003 0.005 0.07 0.08 Comparative Example 2 0.09 0.60 1.80 0.010 0.004 1.10 0.76 0.33 0.05 0.15 - - - - 0.05 0.005 0.006 0.08 / Comparative Example 3 0.05 0.55 0.65 0.009 0.004 1.00 3.55 0.52 0.34 0.12 - - - - - 0.004 0.007 0.12 /

[0038] The welding wire steel is forged into a cross section of 50×50mm. 2 The square billet is forged at a controlled temperature of 1150–1250℃. The forged billet is then held at 1200℃ for 3 hours, followed by wire rod rolling at 850–900℃, sizing and wire drawing at 810–830℃, and slow cooling at 730–480℃ for 10 minutes to finally produce a billet with a diameter of [missing information]. The wire rod is then processed through pickling, borax treatment, rough drawing (φ5.5mm→φ2.35mm), first fine drawing (φ2.35mm→φ1.25mm), second fine drawing (φ1.25mm→φ1.175mm), and copper plating to produce φ1.2mm finished welding wire.

[0039] Performance testing

[0040] Welding tests were conducted on typical joints of the finished welding wires of Examples 1-7 and Comparative Examples 1-3. The specific welding parameters for each welding wire are shown in Table 2. The test plates used for welding were made of Q350EWR1 corrosion-resistant steel with a thickness of 16mm, a yield strength of 370MPa, a tensile strength of 537MPa, an elongation of 22.5%, and a low-temperature impact of 214J at -40℃.

[0041] Table 2 Welding parameters for CO2 gas shielded welding in Examples 1-7 and Comparative Examples 1-3

[0042]

[0043] The weldability of the welding wire was observed during the welding process, and the actual welding photographs of Example 2 and Comparative Example 1 are shown below. Figure 1 (a1) and Figure 1 (b1) The welding wire of the present invention exhibits good weld formation during welding, with almost no arc interruption during welding, good weld continuity, and low welding spatter rate. In contrast, the welding wire of the comparative example frequently experiences arc interruption during welding, has poor weld continuity, and a high spatter rate, requiring fine grinding after each layer is welded. After welding, weld sections were taken from defect-free areas, and the chemical composition of the weld metal after welding with each welding wire was tested according to GB / T 4336 "Spark Source Atomic Emission Spectroscopy Analysis Method (Conventional Method) for Carbon Steel and Medium-Low Alloy Steel". The specific results are shown in Table 3. The results indicate that the welding wire developed in this invention, through optimized alloy element ratios, has low Si and Mn burn-off rates.

[0044] Table 3 Chemical composition (wt.%, balance Fe) of weld metals after CO2 gas shielded welding in Examples 1-7 and Comparative Examples 1-3

[0045]

[0046]

[0047] The macroscopic cross-sections of the joints in Examples 1-7 and Comparative Examples 1-3 were sanded with sandpaper at 100x to 1500x. Subsequently, weld inclusions in each sample were observed under a 200x metallographic microscope. Examples of weld inclusion observations in Example 2 and Comparative Example 1 are shown below. Figure 1 (a2) and Figure 1 (b2). Simultaneously, the 1mm diameter weld in both the embodiment and the comparative example was analyzed. 2 The size distribution of inclusions within the region was statistically analyzed, and the results are shown in Table 4. The results indicate that after CO2 gas shielding welding, the inclusions in the weld are diffusely distributed, and there is a clustering phenomenon among the inclusions. The size statistics in Table 4 show that the number of inclusions larger than 1 μm in the weld of the welding wire in this embodiment is relatively small, accounting for about 10%, while in the comparative example, the number of inclusions larger than 1 μm accounts for about 50%.

[0048] Table 4. Size distribution of inclusions in CO2 gas shielded welds of Examples 1-7 and Comparative Examples 1-3.

[0049]

[0050] Samples of the weld metals that passed flaw detection in Examples 1-7 and Comparative Examples 1-3 were taken for testing of their mechanical properties and corrosion resistance. The tensile properties of the weld metals were sampled and tested according to GB / T 228.1, and the impact properties were sampled and tested according to GB / T 2650. Three impact samples were taken from each sample to minimize errors. For the testing of weld metal corrosion resistance, in accordance with 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 Q350EWR1 base metal and weld metal for 120 hours in a cyclic immersion accelerated corrosion test chamber. The relative corrosion rates of the base metal and the weld metal of the examples and comparative examples after 120 hours were calculated (relative corrosion rate = |(base metal weight loss - weld metal weight loss) / base metal weight loss × 100%|) to evaluate the atmospheric corrosion resistance of the base metal and weld metal. The test results of mechanical properties and corrosion resistance are shown in Table 5.

[0051] Table 5. Test results of corrosion resistance and mechanical properties of weld metals after CO2 gas shielded welding in Examples 1-7 and Comparative Examples 1-3.

[0052]

[0053] As can be seen from the mechanical property test results in Table 5, the strength of both the example and the comparative example can match that of Q350EWR1. However, compared with the impact toughness of the example, the low-temperature impact toughness of the CO2 gas shielded weld metal in the comparative example at -40℃ is significantly reduced, only maintaining around 35J. Observation of the weld microstructure of the example and the comparative example reveals that... Figure 2 As shown, the weld metal in the embodiment has a high density of acicular ferrite, while the weld metal in the comparative example has a lower amount of acicular ferrite, dominated by granular bainite and coarse ferrite. High-density acicular ferrite can provide large-angle grain boundaries that promote crack propagation, effectively improving crack propagation performance. Additionally, the inclusions in the embodiment are smaller (e.g., ...). Figure 1 This further reduces crack sensitivity and increases crack initiation efficiency.

[0054] The results of the accelerated corrosion test of the weld metal after CO2 gas shielded welding in Examples 1-7 and Comparative Examples 1-3 also indicate that the relative corrosion rate between the weld metal and the base metal in the examples is between 6.74% and 8.10%, meeting the requirement of less than 10% as required by railway vehicle standards, indicating that the weld metal can achieve a match with the base metal. In contrast, the relative corrosion rate between the comparative examples and the base metal is higher than 13%, indicating that the corrosion performance of the weld metal after CO2 gas shielded welding in the comparative examples is poor. Analysis of the rust layer on the surface of the samples after 48 hours of accelerated corrosion testing in the examples and comparative examples reveals that... Figure 3 The rust layer on the surface of the weld metal in the comparative example was relatively loose, unevenly distributed, and cracked. In contrast, the rust layer on the surface of the weld metal in the embodiment was evenly distributed and highly dense. This indicates that the optimized ratio of alloying elements in the embodiment is conducive to the formation of a stable and dense rust layer, which is beneficial to obtaining high corrosion resistance of CO2 gas shielded weld metal.

[0055] 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 included in the following mass percentages are: C: 0-0.04, Si: 0.85-1.10, Mn: 0.90-1.15, Cr: 1.50-2.70, Ni: 2.10~2.40, Cu: 0.18-0.34, Ti: 0.035~0.055, Zr: 0.015-0.035, Ce: 0.035-0.055, V: 0.025-0.050, B: 0.0015-0.003, O: ≤0.005, N: 0.003-0.009, with the balance being Fe and other unavoidable impurities; the chemical composition of the welding wire, calculated by weight percentage, satisfies 0.09≤σ≤0.17, 0.04≤ω≤0.12, where: σ = (Ti + 2Zr + 3Ce) / ( Si+0.75Mn), ω= N / (B+2V).

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

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