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

Abstract

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

Description

Technical Field

[0001] The invention belongs to the field of corrosion-resistant steel welding materials for railway vehicles, and in particular relates to a high-corrosion-resistant submerged arc welding material and an application thereof. Background Art

[0002] Weathering steel, as a steel with excellent corrosion resistance, has become popular since the mid-20th century and has been widely used in the fields of construction, bridges and railways. Especially in the field of railways, 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 are moving towards large axle weights, large loads, and high corrosion resistance, weathering steel for railway vehicles has gradually developed from traditional 09CuPCrNi and O450NQR1 steels to Q350EWR1-Q450EWR1 steels with high corrosion resistance. The specific application of this series of high corrosion-resistant steels in railway freight cars is mainly welded structural parts. Since railway cars have to bear dynamic loads and have high requirements for crack resistance, solid welding wires are generally used for welding, especially submerged arc welding solid welding wires, which have been widely used in thick-gauge car flat butt joints or ship angle joints. In order to ensure that the corrosion resistance of the weld metal matches that of the parent material, this type of submerged arc welding wire generally adopts the same alloy system as the Q350EWR1-Q450EWR1 steel. A high proportion of Cr elements are often added to the welding wire, which causes a large amount of side plate ferrite and coarse M / A components to be produced in the weld of the submerged arc welding, resulting in low impact toughness of the weld. Reducing the Cr content of the welding wire improves the impact toughness of the weld, but the corrosion performance cannot match that of the parent material. The existing Q350EWR1-Q450EWR1 steel matching submerged arc welding solid welding wire has the problem of insufficient weld toughness or insufficient corrosion performance. Therefore, it is necessary to redesign and optimize the composition system of the welding wire so that the weld has both high corrosion resistance and excellent impact toughness. Summary of the invention

[0003] To solve the above problems, the present invention provides a high corrosion-resistant submerged arc welding material, comprising 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 is Fe and other inevitable impurities.

[0004] The present invention also provides a welding wire, the composition of which includes the above welding material.

[0005] Furthermore, the Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O and N in the welding wire are calculated by weight percentage and satisfy the following conditions: 0.07≤λ≤0.17, 2.8≤τ≤4.0, wherein: 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 application of the welding material in railway vehicle welding.

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

[0010] The invention provides a high corrosion-resistant submerged arc welding wire for railway vehicles, which can take into account both excellent corrosion resistance and low-temperature toughness of a weld. The chemical composition comprises, 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 and the balance Fe and other inevitable impurities. The chemical composition of Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O and N in the welding wire is calculated by weight percentage to meet the following conditions: 0.07≤λ≤0.17, 2.8≤τ≤4.0, the λ=(1.58O+N) / (Ti+1.5Ca+2.0Ce+0.7Sn), the τ=(3Ni+Mo+1.5Cr+Si+2Cu+6Sn) / (Ni+8Mo+3Sn+7Nb). The present invention adopts the alloy system of Ni-Cr-Cu-Mo-Sn, which effectively ensures the rust layer stability and corrosion resistance of the weld; by regulating the λ range, the morphology, size and composition of the inclusions are effectively regulated, giving full play to the role of the inclusions as the nucleation site of acicular ferrite; on the basis of regulating λ, the τ range is further regulated, so as to achieve the balance between excellent corrosion resistance and low temperature toughness of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0013] Figure 2 The microstructure scanning diagram of the weld metal after CO2 gas shielded welding wire provided by the present invention and the microstructure scanning diagram of the weld metal after CO2 gas shielded welding provided by the comparative example, wherein (a) is the microstructure scanning diagram of the weld after CO2 gas shielded welding wire described in Example 4, and (b) is the microstructure scanning diagram of the weld metal after CO2 gas shielded welding wire described in Comparative Example 2.

[0014] Figure 3 The present invention provides a CO2 gas shielded welding wire, and the surface rust layer morphology of the weld metal after 48 hours of accelerated corrosion test by immersion, and the surface rust layer morphology of the weld metal after 48 hours of accelerated corrosion test by immersion, provided by the comparative example, wherein (a) is the surface rust layer morphology of the weld metal after 48 hours of accelerated corrosion test by immersion, provided by the CO2 gas shielded welding wire described in Example 5, and (b) is the surface rust layer morphology of the weld metal after 48 hours of accelerated corrosion test by immersion, provided by the comparative example 3. DETAILED DESCRIPTION

[0015] Now, various exemplary embodiments of the present invention are described in detail. The methods in the examples are conventional methods unless otherwise specified, and the reagents used are conventional commercially available reagents or reagents prepared by conventional methods unless otherwise specified. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features and embodiments of the present invention.

[0016] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0017] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0018] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

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

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

[0021] The invention provides a high corrosion-resistant submerged arc welding wire for railway vehicles, which can take into account both excellent corrosion resistance and low-temperature toughness of a weld. The chemical composition comprises, 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 and the balance Fe and other inevitable impurities.

[0022] The chemical compositions of Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O and N in the welding wire, calculated by weight percentage, satisfy the following conditions: 0.07≤λ≤0.17, 2.8≤τ≤4.0, wherein 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] Measured by mass percentage, the submerged arc welding wire provided by the present invention includes 0% to 0.04% C. Adding a certain amount of C element to the welding wire is beneficial to the rolling of the wire rod, increasing the stiffness of the welding wire, and at the same time is beneficial to improving the strength of the weld. However, when the C content is too much, it will lead to a significant increase in the carbon equivalent, reduce plasticity, and also increase the crack sensitivity of the weld joint.

[0024] In terms of mass percentage, the submerged arc welding wire provided by the present invention includes 0.15% to 0.30% Si. Si can form a Si-rich protective film on the surface of the weld metal, refine α-FeOOH, reduce the corrosion rate, and improve corrosion resistance. At the same time, as one of the main alloying elements of the weld, Si has a strong deoxidation effect and improves the fluidity of the molten pool. However, if its content is too high, coarse side plate ferrite and M / A components will appear in the weld microstructure. Considering that the submerged arc welding flux will transfer Si to 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 the present invention includes Mn: 0.85-1.10 by mass percentage. The Mn element in the welding wire is also the main deoxidizer, which is beneficial to reduce the oxygen content of the weld metal by combining with Si, increase the strength and crack resistance of the weld metal, and Mn also has a desulfurization effect. However, as Mn increases, it will cause serious segregation, deteriorating the drawing performance and process performance of the welding wire.

[0026] The submerged arc welding wire provided by the present invention includes Cr: 2.10-2.60 by mass percentage. During the corrosion process of steel, the Cr element can be enriched on the surface of the substrate to form an iron-chromium multi-element alloy oxide, fill the microcracks and voids of the rust layer, increase the density of the rust layer, and improve the 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 the Cr content in the weld will cause the increase and coarsening of the M / A component, reducing the toughness of the weld.

[0027] The submerged arc welding wire provided by the present invention includes 1.85% to 2.30% Ni by mass percentage. The addition of Ni makes the rust layer crystallized finer, makes it easier for γ-FeOOH to be transformed into stable α-FeOOH, inhibits the invasion 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, too high a Ni content can also cause segregation and increase the viscosity of the welding pool, reducing the drawing performance and metallurgical quality of the welding wire.

[0028] The submerged arc welding wire provided by the present invention includes Cu: 0.14% to 0.30% by mass percentage. Cu is enriched on the surface of the weld metal during the corrosion process of steel to form a dense oxide layer, which can make the grains of the inner rust layer finer and denser. Moreover, Cu is a precipitation strengthening element, which can improve the strength and toughness of the weld within a certain range, but too high a Cu content will make the welding slag viscous and difficult to clean, and increase the tendency of the weld to thermal cracking. 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 the present invention includes Ti: 0.015% to 0.030% by mass percentage. Ti has active chemical properties and strong deoxidation effect, which can effectively protect the transition of Si and Mn to the weld. Its oxide is enriched on the surface of inclusions and can effectively play the role of ferrite nucleation site. However, if the Ti element content is too high, the size of the inclusions in the weld will be significantly coarsened, which will not only increase the crack sensitivity, but also cause serious pitting problems.

[0030] The submerged arc welding wire provided by the present invention includes Mo: 0.05% to 0.18% by mass. Adding Mo element to the weld can not only form molybdate, increase the density of the rust layer, and improve the atmospheric corrosion resistance of the steel, but also significantly reduce the phase transition temperature and inhibit the formation of coarse blocky ferrite. However, excessive Mo content will lead to the formation of enriched areas near the grain boundaries, promote the formation of lamellar and network-shaped Mo phases near the grain boundaries, reduce the continuity of the matrix, and reduce the toughness of the weld.

[0031] Measured by mass percentage, the submerged arc welding wire provided by the present invention includes Sn: 0.020%~0.040%. It is generally known that Sn is a harmful element in steel, which will be segregated at the columnar grain boundaries and reduce the low-temperature toughness of the weld; but the Sn element can significantly improve the corrosion resistance of the matrix under industrial atmospheric conditions, especially in the weld, the Sn element is precipitated on the surface of the weld metal, and it is oxidized to SnO2 to achieve the effect of improving corrosion resistance, and Sn can react with O and N in the steel to form chemicals attached to the surface of the inclusions, playing the role of acicular ferrite nucleation site. Taking all factors into consideration, the Sn in the weld is controlled in the range of 0.020%~0.040%.

[0032] Measured by mass percentage, the submerged arc welding wire provided by the present invention includes Nb: 0% to 0.025%. Nb can be combined with N and C elements to achieve the effect of purifying the weld. Nb (C, N) particles can precipitate at the austenite grain boundary, pin the grain boundary, inhibit the growth of austenite, and play a role in refining the weld structure. However, too high a Nb content will reduce the weldability and increase the crack sensitivity of the weld joint.

[0033] In terms of mass percentage, the submerged arc welding wire provided by the present invention includes Ca: 0% to 0.015%. The Ca element can improve the fluidity of the welding molten pool, improve the alloy element transition of Si and Mn, and reduce the influence of the residual rust on the surface of the steel plate on the welding processability and the mechanical properties of the weld. At the same time, the addition of the Ca element can also react with O in the steel, and the formed inclusions play the role of ferrite heterogeneous nucleation. However, the increase in the Ca content will cause the molten pool of the submerged arc welding to react violently, which is not conducive to obtaining a good weld formation.

[0034] In terms of mass percentage, the submerged arc welding wire provided by the present invention includes Ce: 0.020% to 0.040%. Ce can also improve the fluidity of the molten pool in the weld, improve the transition of the alloy elements of Si and Mn, and can also disperse and refine the inclusions, which is conducive to 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, it is difficult to smelt the welding wire steel with a high Ce content. When the Ce content is too much during welding, it is not conducive to obtaining excellent welding metallurgical quality.

[0035] Measured by mass percentage, the submerged arc welding wire provided by the present invention comprises O: 0.003% to 0.007%, N: 0.004% to 0.010%. The present invention controls N and O in the welding wire steel to achieve the effect of regulating welding metallurgical quality and weld inclusions, but excessive O and N content will cause high weld porosity and burnout of alloy elements.

[0036] The submerged arc welding wire provided by the present invention further comprises a balance of Fe in terms of mass percentage. In the present invention, Fe is a matrix element.

[0037] In the present invention, the chemical compositions of Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O and N in the welding wire are calculated by weight percentage and satisfy the following conditions: 0.07≤λ≤0.17, 2.8≤τ≤4.0, wherein 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] In order to ensure that the corrosion resistance of the welding wire of the present invention matches that of the high corrosion-resistant steel for railway vehicles of the Q350EWR1-Q450EWR1 level, a Ni-Cr-Cu-Mo-Sn alloy system is adopted. However, a large amount of Ni and Cr are added to the alloy system, which can significantly increase the viscosity of the welding molten pool, reduce the fluidity of the molten pool, and cause large-sized inclusions to appear in the weld. The large-sized inclusions will not only become the starting point of cracks and increase the crack sensitivity, but also reduce the probability of serving as the nucleation site of acicular ferrite, so that granular bainite and large-sized block ferrite structures will appear in the weld, resulting in difficulty in achieving both excellent corrosion resistance and low-temperature toughness of the weld. The present invention regulates the composition of Ti, Ca, Ce, Sn, O and N to meet the range of λ. On the one hand, they can form a complex with Si in the steel to improve the fluidity of the molten pool. On the other hand, the shape, size and composition of the inclusions are regulated to make the silicate inclusions dispersed and transformed into spherical shapes. The oxides or nitrides of Ti, Ca, Ce and Sn are attached to the surfaces of the silicate inclusions to play the role of effective acicular ferrite nucleation sites.

[0039] On the basis of regulating λ, Ni, Mo, Cr, Cu, Si, Nb, Ti and Sn are further regulated to meet the range of τ, and the matching of the elements in the weld that mainly play a role in weld corrosion resistance and the elements that play a role in refining the weld organization is regulated. While improving the rust layer structure and density and improving the weld corrosion resistance, the acicular ferrite microstructure 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 welding wire steel according to the above welding wire composition;

[0042] (2) forging the ingot obtained in step (1) at a forging temperature of 1000° C. to 1050° C.;

[0043] (3) The forging obtained in step (2) is subjected to wire rod rolling at a rolling temperature of 830-880° C.; the wire rod diameter

[0044] (4) subjecting the wire rod obtained in step (3) to a slow cooling treatment, wherein the slow cooling temperature ranges from 740° C. to 490° C., and the slow cooling time is 10 min;

[0045] (5) The wire rod obtained in step (4) is subjected to a drawing and diameter reduction treatment, and the wire rod is reduced to

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

[0047] The component system provided by the present invention is easy to smelt and prepare, and the preparation process of the welding wire is simple and easy to control. The technical scheme of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Seven furnaces of welding wire steel of the embodiment of the present invention and three furnaces of welding wire steel of the comparative example were refined in a 75kg vacuum induction furnace, wherein the element ratio of the welding wire steel of the embodiment of the present invention meets the requirements of the present invention. The welding wire steel of the embodiment and the comparative example were melted and cast in sequence according to a certain element composition ratio to obtain a cast alloy billet, and the composition of the welding wire steel of the embodiment and the comparative example was detected according to GB / T4336 "Spark Source Atomic Emission Spectroscopy Analysis Method for Carbon Steel and Medium and Low Alloy Steel (Conventional Method)", and the specific chemical composition is shown in Table 1.

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

[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] The welding wire steels of Examples 1 to 7 and Comparative Examples 1 to 3 were prepared, and the specific process of preparing each welding wire steel is statistically shown in Table 2. The welding wire steels of the Examples and Comparative Examples prepared by this process had no wire breakage during the drawing process, and the copper plating thickness on the surface of the welding wire was uniform, without warping and cracking.

[0052] Table 2 Main process parameters for preparing submerged arc welding wires of Examples 1 to 7 and Comparative Examples 1 to 3

[0053]

[0054]

[0055] Performance measurement

[0056] The welding wires prepared in Examples 1 to 7 and Comparative Examples 1 to 3 were subjected to welding tests of typical butt joints. The specific welding process parameters are shown in Table 3. The welding test plate was made of Q450EWR1 corrosion-resistant steel with a thickness of 24 mm. The steel plate had a yield strength of 474 MPa, a tensile strength of 594 MPa, an elongation of 22%, and a low-temperature impact of -40°C of 201 J.

[0057] Table 3 Submerged arc welding process parameters of Examples 1 to 7 and Comparative Examples 1 to 3

[0058]

[0059] During the actual welding process of the welding wires of the comparative examples and the embodiments, the appearance of the weld surface was observed, and the weld morphology of the welds of the embodiment 2 and the comparative example 1 was respectively Figure 1 (a1) and Figure 1 (b1), the results show that the welding wire of the embodiment has smooth wire movement, uniform weld distribution and good weld formation during the actual welding process, while the welding wire of the comparative example has arc breaking problem during welding, and the undercut is serious during welding, and the weld formation is poor. After welding, the welds were all inspected, and the macroscopic cross-section of the joint was intercepted in the defect-free area of ​​the embodiment and the comparative example, and the weld composition was tested. The results are shown in Table 4.

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

[0061]

[0062]

[0063] After the component detection was completed, the macroscopic cross-sections of the joints of the embodiment and the comparative example were sandpapered, and the inclusions in the welds were observed and counted under a metallographic microscope. The morphology of the inclusions in the embodiment 2 and the comparative example 1 was shown in FIG. Figure 1 (a2) and Figure 1 (b2), the statistical results of the inclusion size distribution are shown in Table 5. It can be found from the inclusion morphology and statistical results that in the embodiment, the average size of the inclusions is relatively small, mostly between 0.2-1.0 μm, and is in a dispersed distribution state, while in the comparative example, the inclusions in the weld are aggregated, the average size is relatively large, and the proportion of inclusions of 1.8-2.2 μm is significantly increased.

[0064] Table 5 Size distribution of inclusions in submerged arc welding seams of Examples 1 to 7 and Comparative Examples 1 to 3

[0065]

[0066]

[0067] The welds of Examples 1 to 7 and Comparative Examples 1 to 3 that passed the flaw detection were sampled and the mechanical properties of the weld metal were tested. The tensile properties of the weld metal were sampled and tested in accordance with GB / T 228.1, and the impact sampling and performance testing were in accordance with GB / T 2650. Three impact samples were taken for each sample to reduce errors. The test results of the mechanical properties are shown in Table 6. The results show that when the welding wire of this embodiment is matched with different fluxes, the weld metal has excellent weld strength and toughness, while when the welding wire of the comparative example is matched with different fluxes, although the weld metal strength can match that of the base material, the impact performance is reduced. By performing EBSD characterization on the weld microstructure of Example 4 and Comparative Example 2, it can be found that Figure 2 The example weld has a large amount of acicular ferrite structure, and its grain boundaries are mostly large-angle grain boundaries. The high-density large-angle grain boundaries play a role in improving the impact toughness. The comparative weld is mainly composed of blocky ferrite and granular bainite, and its high-angle grain boundary density is low, so a relatively low impact toughness is obtained.

[0068] Table 6 Mechanical properties test results of weld metal after submerged arc welding of Examples 1 to 7 and Comparative Examples 1 to 3

[0069]

[0070] The welds of Examples 1 to 7 and Comparative Examples 1 to 3 that passed the flaw detection were sampled and the relative corrosion performance of the weld metal and the base metal was tested. The test was conducted with reference 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. The accelerated corrosion test of the Q450EWR1 base metal and weld metal was conducted in a 120-hour immersion accelerated corrosion test chamber. The relative corrosion rates of the base metal and the weld metals of the Examples and Comparative Examples 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 after 120 hours are shown in Table 6. The results show that the submerged arc welding weld metals of the embodiments have a relative corrosion rate of less than 9.4% with the Q450EWR1 parent material, which meets the standard requirement of less than 10%, while the relative corrosion rate of the comparative welding wire with the parent material is higher than 14%, indicating that the corrosion performance is far behind that of the parent material, and the corrosion resistance of the parent material cannot be matched. In addition, the accelerated corrosion coupons of Example 6 and Comparative Example 3, which were immersed for 60 hours and 96 hours, were observed respectively. The surface corrosion pits of the embodiment coupons were shallow, while there were a large number of obvious depressions on the surface of the comparative coupons, indicating that the corrosive liquid had a greater erosion effect on the weld of the comparative example, which was not conducive to obtaining excellent corrosion resistance.

[0071] Table 7 Comparison results of corrosion weight loss of submerged arc welding weld metal circumferential immersion test and parent metal in Examples 1 to 7 and Comparative Examples 1 to 3

[0072]

[0073] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A highly corrosion-resistant submerged arc welding material, characterized in that: Including 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, and the balance is Fe and other inevitable impurities.

2. A welding wire, characterized in that: The composition comprises the welding material as claimed in claim 1.

3. The welding wire according to claim 2, characterized in that The Ni, Mo, Cr, Cu, Si, Nb, Ti, Ca, Ce, Sn, O and N in the welding wire are calculated by weight percentage and meet the following requirements: 0.07≤λ≤0.17, 2.8≤τ≤4.0, wherein: λ=(1.58O+N) / (Ti+1.5Ca+2.0Ce+0.7Sn), τ=(3Ni+Mo+1.5Cr+Si+2Cu+6Sn) / (Ni+8Mo+3Sn+7Nb).

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

5. The welding wire according to claim 2, characterized in that The copper plating thickness of the welding wire is 0.14-0.18 μm.

6. Use of the welding material as claimed in claim 1 in railway vehicle welding.

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