A welding material and welding method for 650MPa grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm.

Abstract

This invention provides a welding material and welding method for 650MPa-grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm, belonging to the technical field of welding materials. The welding material provided by this invention comprises the following elements by mass percentage: C: 0.08-0.12%, Si≤0.09%, Mn: 1.70-1.95%, Cr: 0.30-0.45%, Ni: 0.05-0.50%, Mo: 0.40-0.58%, Ti: 0.13-0.24%, V: 0.04-0.05%, B: 0.0005-0.0030%, Mg≤0.005%, Zr≤0.020%, La≤0.030%, P≤0.012%, S≤0.005%, Pb+Sn+As+Sb+Bi≤0.008%, and balance Fe.

Description

Technical Field

[0001] This invention relates to the field of welding materials technology, and in particular to a welding material and welding method for 650MPa grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm. Background Technology

[0002] With the rapid development of my country's social economy, the increasing size, high parameters, and safety of steel structures have become inevitable trends, leading to a continuously expanding demand for high-performance, easily weldable medium-thick steel plates. High-heat-input welding technologies (welding heat input not less than 50 kJ / cm), represented by multi-wire submerged arc welding, narrow-gap submerged arc welding, gas-electric vertical welding, and electroslag welding, can balance welding efficiency and production costs, and have been widely researched and applied in various industries. However, under high-heat-input welding conditions, as the welding heat input increases, weld grain coarsening, heat-affected zone area expansion, and other welding defects increase, causing a sharp deterioration in the low-temperature impact toughness of the weld metal. The difficulty in matching the mechanical properties of the weld metal with the high heat input has become a key issue restricting the further development of efficient welding technologies.

[0003] Chinese invention patent application CN201410728048.4 discloses a "high heat input submerged arc welding wire" suitable for welding heat input of 60-160 kJ / cm. This submerged arc welding wire pins austenite grain boundaries by adding 0.01-0.05% Ti to form TiN, thereby preventing austenite grain growth. On the other hand, it promotes the formation of acicular ferrite by adding alloying elements such as Si, Mn, Ti, Al, Ce, and Mg to form composite oxide inclusions of high-melting-point Si, Mn, Ti, Al, Ce, and Mg. However, during high heat input welding (greater than 50 kJ / cm), Ti burn-off is relatively severe, and the content of 0.01-0.05% titanium transitioning into the weld metal is relatively small. In addition, in the embodiments of this patent, high heat input welding of butt test plates was performed. The weld metal fusion ratio caused by high heat input welding is relatively large, and the effective components of the weld metal are further diluted. Therefore, the low-temperature impact toughness at -40℃ in the weld center of the embodiment is relatively low. In addition to issues such as element burn-off during high-heat-input welding, the slow cooling rate of the weld metal leads to the formation of proeutectoid ferrite at grain boundaries, which significantly impacts the weld metal's toughness. Therefore, it is necessary to suppress the formation of proeutectoid ferrite and side-plate ferrite in high-heat-input welding. However, existing technologies have not provided effective solutions to these problems.

[0004] Therefore, providing a welding material for 650MPa-grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm has become a technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a welding material and welding method for 650MPa grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm. The welding material provided by this invention is suitable for welding with a high heat input of 75kJ / cm, and the weld metal produced has a tensile strength of 650MPa grade, while also having high impact toughness at -40℃.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a welding material for 650MPa grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm, comprising the following elements by mass percentage: C: 0.08-0.12%, Si: ≤0.09%, Mn: 1.70-1.95%, Cr: 0.30-0.45%, Ni: 0.05-0.50%, Mo: 0.40-0.58%, Ti: 0.13-0.24%, V: 0.04-0.05%, B: 0.0005-0.0030%, Mg: ≤0.005%, Zr: ≤0.020%, La: ≤0.030%, P: ≤0.012%, S: ≤0.005%, Pb+Sn+As+Sb+Bi: ≤0.008%, and balance Fe.

[0008] Preferably, the mass percentages of elements in the 650MPa grade multi-wire submerged arc welding material have the following relationships: 0.72≤α≤1.33; 87.41≤β≤124.36; 655.69≤γ≤772.68; where,

[0009] α=(62.17Si+19.33Mn+25.01Zr) / (45.33Cr+58.31Ni+20.32Mo);

[0010] β=42.56Mn+75.88Ti+123.28V+520.16B+191.14Mg+482.66La;

[0011] γ=405.54+105.14C+92.35Mn+54.06Cr+88.72Ni+109.86Mo+153.61Ti+97.88Zr.

[0012] Preferably, the surface of the welding material is further coated with a copper plating layer.

[0013] Preferably, the thickness of the copper plating layer is 0.08 to 0.12 μm.

[0014] The present invention also provides a welding method for the welding materials described in the above technical solution, comprising: performing multi-wire submerged arc welding on the base metal with welding materials and sintering flux under a heat input of 75 kJ / cm to obtain a welded part.

[0015] Preferably, the basicity of the sintering flux is 2.2 ≤ B. ⅡW ≤2.5.

[0016] Preferably, the base metal is made of Q370qE, Q420qE, or Q500qE.

[0017] Preferably, the bevel form of the multi-wire submerged arc welding is a 30-60° V-groove or a 30-60° double V-groove.

[0018] Preferably, the welding position of the multi-wire submerged arc welding is horizontal or ship-shaped.

[0019] Preferably, the layer temperature of the multi-wire submerged arc welding is ≤160℃.

[0020] The welding material for 650MPa grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises the following elements by mass percentage: C: 0.08-0.12%, Si: ≤0.09%, Mn: 1.70-1.95%, Cr: 0.30-0.45%, Ni: 0.05-0.50%, Mo: 0.40-0.58%, Ti: 0.13-0.24%, V: 0.04-0.05%, B: 0.0005-0.0030%, Mg: ≤0.005%, Zr: ≤0.020%, La: ≤0.030%, P: ≤0.012%, S: ≤0.005%, Pb+Sn+As+Sb+Bi: ≤0.008%, and balance Fe. In this invention, C is the main strengthening element, significantly improving the tensile strength of the weld metal. Mn also has excellent deoxidizing ability, not only removing FeO from steel but also forming MnS with S to eliminate the harmful effects of S. Simultaneously, Mn can improve the hardenability of the weld metal, refine the microstructure, and enhance its mechanical properties through solid solution strengthening. Cr can dissolve in ferrite to produce solid solution strengthening, thereby improving the strength, hardness, and plasticity of the weld metal. Ni can effectively improve the yield strength of the weld metal. Mo can refine the grain size to improve the strength and hardness of the weld metal, prevent temper brittleness and overheating tendency, and also improve the plasticity of the weld metal, reducing the tendency to crack. Ti is a microalloying element that can make the microstructure of the weld metal more uniform and significantly improve impact toughness. Furthermore, Ti can form dispersed oxides and nitrides that hinder austenite grain growth. The composite oxide inclusions formed by Ti with Si, Mn, Al, and Mg are beneficial to the nucleation and growth of acicular ferrite. The invention significantly promotes the formation of acicular ferrite in the weld metal, effectively improving the low-temperature toughness of the weld metal under high heat input. V combines with C and N elements to precipitate micron-sized V(C,N) particles from the matrix, which, as heterogeneous nucleation particles, can effectively promote the intragranular nucleation of acicular / blocky ferrite in the weld heat-affected zone, refine the microstructure, and greatly improve the weldability of the steel plate under high heat input. B is a strong grain boundary segregating element that can preferentially occupy grain boundary positions and avoid the segregation of impurity elements. At the same time, B can also reduce the interfacial energy and control the precipitation of proeutectoid ferrite. In addition, Ti and B have a mutually protective relationship, that is, the addition of Ti can prevent B from combining with N, improve the grain boundary segregation effect, and B can protect Ti from excessive oxidation. Therefore, by controlling the content of Ti and B, this invention can improve the toughening effect of the weld and reduce the ductile-brittle transition temperature of the weld metal. P, S, and Pb+Sn+As+Sb+Bi are all harmful elements. This invention strictly controls their content to effectively reduce their adverse effects on the weld microstructure.

[0021] The results of the embodiments show that the welding material for multi-wire submerged arc welding provided by the present invention has a yield strength ≥500MPa, tensile strength ≥650MPa, elongation ≥20% of weld metal under a welding heat input of 75kJ / cm, and an impact absorption energy of 120~144J at -40℃, which meets the requirements of relevant domestic standards / specifications and has sufficient impact absorption energy margin. At the same time, the welding process performance is stable under a high heat input of 75kJ / cm, the molten pool has good fluidity, the deposited metal is aesthetically pleasing, and the crack resistance is excellent. Attached Figure Description

[0022] Figure 1 This is an SEM image of the weld metal obtained by welding under a welding heat input of 75 kJ / cm in Application Example 1 of the present invention.

[0023] Figure 2 The image shows a SEM image of the weld metal obtained by welding under a welding heat input of 75 kJ / cm in Comparative Application Example 1 of this invention. Detailed Implementation

[0024] This invention provides a welding material for 650MPa grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm, comprising the following elements by mass percentage: C: 0.08-0.12%, Si: ≤0.09%, Mn: 1.70-1.95%, Cr: 0.30-0.45%, Ni: 0.05-0.50%, Mo: 0.40-0.58%, Ti: 0.13-0.24%, V: 0.04-0.05%, B: 0.0005-0.0030%, Mg: ≤0.005%, Zr: ≤0.020%, La: ≤0.030%, P: ≤0.012%, S: ≤0.005%, Pb+Sn+As+Sb+Bi: ≤0.008%, and balance Fe.

[0025] The welding material for 650MPa grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises C: 0.08-0.12%, preferably 0.09-0.11%. By adding C and controlling its content within the above range, this invention can utilize C as the main strengthening element to significantly improve the tensile strength of the weld metal, reduce the tendency of the weld to hot crack and the tendency of the weld heat-affected zone to cold crack, thereby avoiding a decrease in the toughness of the weld metal.

[0026] The welding material for 650MPa-grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises Si: ≤0.09%, preferably 0.01-0.09%, and more preferably 0.02-0.08%. This invention utilizes Si's excellent deoxidizing properties by adding Si and controlling its content within the above range. This deoxidizes the weld pool metal, eliminating the adverse effects of inclusions such as FeO on the weld. Furthermore, since most of the Si is dissolved in the ferrite matrix, the solid solution strengthening effect improves the mechanical properties of the weld metal. In addition, controlling the Si content within the above range avoids the problem of excessive Si leading to a significant increase in weld metal grain size and a decrease in toughness.

[0027] The welding material for 650MPa grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises Mn: 1.70-1.95%, preferably 1.72-1.94%, and more preferably 1.75-1.93%, by weight percentage. This invention utilizes Mn's excellent deoxidizing ability by adding Mn and controlling its content within the above range. Mn not only removes FeO from steel but also forms MnS with S to eliminate the harmful effects of S. Simultaneously, Mn improves the hardenability of the weld metal, refines the microstructure, and enhances the mechanical properties of the weld metal through solid solution strengthening. Furthermore, in this invention, when the Mn content is below 1.2%, the strength of the weld metal does not meet requirements and is not conducive to preventing welding hot cracking; when the Mn content is above 1.9%, martensitic structure is easily formed, leading to a significant decrease in toughness.

[0028] The welding material for 650MPa-grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises Cr: 0.30-0.45%, preferably 0.32-0.42%, and more preferably 0.35-0.4%. By adding Cr and controlling its content within the above range, this invention utilizes the solid solution strengthening effect of Cr dissolved in ferrite, thereby improving the strength, hardness, and plasticity of the weld metal. In this invention, when the Cr content exceeds 0.8%, the toughness of the weld metal decreases significantly.

[0029] The welding material for 650MPa-grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises Ni: 0.05-0.50%, preferably 0.08-0.48%, and more preferably 0.10-0.45%. By adding Ni and controlling its content within the above range, this invention effectively improves the yield strength of the weld metal. In this invention, for every 1% increase in nickel, the yield point of the cladding metal can be increased by 20-50MPa; however, excessively high Ni content can also cause segregation and increase costs.

[0030] The welding material for 650MPa-grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises Mo: 0.40-0.58%, preferably 0.42-0.55%, and more preferably 0.45-0.5%. By adding Mo and controlling its content within the above range, this invention can refine the grain size to improve the strength and hardness of the weld metal, prevent temper brittleness and overheating tendency, and also improve the plasticity of the weld metal, reducing the tendency to crack. In this invention, when the Mo content exceeds 0.6%, it will affect the plasticity of the weld metal.

[0031] The welding material for 650MPa-grade multi-wire submerged arc welding, suitable for 75kJ / cm heat input welding, provided by this invention, comprises Ti: 0.13-0.24%, preferably 0.14-0.23%, and more preferably 0.15-0.2%. By adding Ti and controlling its content within the above range, this invention utilizes the microalloying effect of Ti to make the weld metal microstructure more uniform and significantly improve impact toughness. Simultaneously, the dispersed oxides and nitrides formed by Ti hinder austenite grain growth. The composite oxide inclusions formed by Ti with Si, Mn, Al, and Mg are conducive to the nucleation and growth of acicular ferrite, thereby significantly promoting the formation of acicular ferrite in the weld metal and effectively improving the low-temperature toughness of the weld metal under high heat input. In this invention, due to the use of high heat input welding, Ti burn-off is severe; therefore, controlling the Ti content within the above range ensures that Ti fully exerts its beneficial effects.

[0032] The welding material for 650MPa-grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises V: 0.04-0.05%, preferably 0.041-0.049%, and more preferably 0.042-0.048%. By adding V and controlling its content within the above range, this invention enables V to combine with C and N elements, precipitating micron-sized V(C,N) particles from the matrix. These particles, acting as heterogeneous nucleation sites, effectively promote intragranular nucleation of acicular / blocky ferrite in the weld heat-affected zone, refine the microstructure, and greatly improve the welding performance of steel plates under high heat input.

[0033] The welding material for 650MPa-grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises B: 0.0005-0.0030%, preferably 0.0010-0.0025%, and more preferably 0.0015-0.0020%. This invention utilizes the fact that B is a strong grain boundary segregating element, preferentially occupying grain boundary positions and preventing the segregation of impurity elements by adding B and controlling its content within the above range. Simultaneously, B can reduce interfacial energy and control the precipitation of proeutectoid ferrite. Furthermore, Ti and B have a mutually protective relationship; the addition of Ti can prevent B from combining with N, improving the grain boundary segregation effect, and B can protect Ti from excessive oxidation. Therefore, this invention, by simultaneously adding Ti and B and controlling their contents, can improve the weld toughening effect and reduce the ductile-brittle transition temperature of the deposited metal.

[0034] The welding material for 650MPa-grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises Mg: ≤0.005%, preferably 0.001-0.005%, more preferably 0.002-0.004%. By adding Mg and controlling its content within the above range, this invention can utilize the finely dispersed oxides formed by the combination of Mg and O as nucleation sites to promote the formation of a large amount of acicular ferrite structure, thereby improving the welding performance of the weld against high heat input.

[0035] The welding material for 650MPa-grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises Zr: ≤0.020%, preferably 0.001-0.02%, more preferably 0.005-0.015%. By adding Zr and controlling its content within the above range, this invention can utilize Zr's precipitation strengthening and solid solution strengthening effects to improve the strength of the weld metal, refine and disperse high-melting-point inclusions in the molten pool, improve the fluidity of the molten pool, and Zr also has a nitrogen-fixing effect, which can effectively improve the strength of the weld metal.

[0036] By mass percentage, the welding material for 650MPa-grade multi-wire submerged arc welding suitable for 75kJ / cm heat input welding provided by the present invention includes La: ≤0.030%, preferably 0.001~0.030%, more preferably 0.005~0.025%. The present invention utilizes the addition of rare earth element La and its control within the above-mentioned range. Rare earth La can be enriched in silicate inclusions, causing them to spheroidize and disperse, promoting the nucleation of acicular ferrite and refining the weld microstructure.

[0037] By mass percentage, the welding material for 650MPa grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm provided by the present invention comprises P: ≤0.012%, preferably ≤0.010%. P in the welding material of the present invention is a harmful element, and its content should be strictly controlled to a low level.

[0038] By mass percentage, the welding material for 650MPa grade multi-wire submerged arc welding suitable for 75kJ / cm heat input welding provided by this invention comprises S: ≤0.005%, preferably ≤0.004%. S in the welding material of this invention is a harmful element, and its content should be strictly controlled to a low level.

[0039] The welding material for 650MPa grade multi-wire submerged arc welding, suitable for welding with a heat input of 75kJ / cm, provided by this invention, comprises Pb+Sn+As+Sb+Bi: ≤0.008%, preferably ≤0.007%, based on a mass percentage. Pb+Sn+As+Sb+Bi in the welding material of this invention are all harmful elements, and their content should be strictly controlled to a low level.

[0040] By weight percentage, the welding material for 650MPa grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm provided by the present invention includes the balance Fe.

[0041] In this invention, the mass percentage of elements in the welding material for 650MPa grade multi-wire submerged arc welding suitable for 75kJ / cm heat input welding preferably has the following relationship: 0.72≤α≤1.33; 87.41≤β≤124.36; 655.69≤γ≤772.68.

[0042] In this invention, α is:

[0043] α = (62.17Si + 19.33Mn + 25.01Zr) / (45.33Cr + 58.31Ni + 20.32Mo). This invention, by controlling the content relationship of the above elements to satisfy 0.72 ≤ α ≤ 1.33, enables Si and Mn to transition into the weld and participate in the molten pool reaction during welding, promoting the deoxidation and impurity removal process of the weld, reducing the burn-off of strengthening elements Cr, Ni, and Mo, thereby generating silicate and calcium salt inclusions with low density and easy floating. Simultaneously, Si and Zr can reduce the viscosity of the molten pool and improve fluidity to promote the floating and removal of weld inclusions.

[0044] In this invention, β is:

[0045] β = 42.56Mn + 75.88Ti + 123.28V + 520.16B + 191.14Mg + 482.66La. This invention, by controlling the content relationship of the above elements to satisfy 87.41 ≤ β ≤ 124.36, ensures that appropriately sized and dispersed MnS inclusions, Ti / V / B precipitates, MgO inclusions, La inclusions, and multi-element composite inclusions can act as nucleation sites for ductile needle / massive ferrite, increasing the proportion of needle / massive ferrite in the weld and improving the low-temperature toughness of the weld metal.

[0046] In this invention, γ is:

[0047] γ = 405.54 + 105.14C + 92.35Mn + 54.06Cr + 88.72Ni + 109.86Mo + 153.61Ti + 97.88Zr. This invention, by controlling the content relationship of the above elements to satisfy 655.69 ≤ γ ≤ 772.68, enables the addition of alloying elements in the weld to delay the transformation process of austenite to ferrite, suppress the formation of proeutectoid ferrite and side-plate ferrite, and simultaneously ensure sufficient weld metal strength through grain refinement strengthening, precipitation strengthening, and solid solution strengthening, thereby comprehensively improving the weld's resistance to high heat input.

[0048] In this invention, the surface of the welding material is preferably further coated with a copper plating layer. By coating the surface of the welding material with a copper plating layer, this invention can extend the shelf life of the welding material, enhance its electrical conductivity, and make its welding performance more stable under high heat input conditions.

[0049] In this invention, the thickness of the copper plating layer is preferably 0.08–0.12 μm. By controlling the thickness of the copper plating layer within the above range, this invention enables the copper plating layer to have good protective and conductive properties.

[0050] The welding material provided by this invention is suitable for welding with a high heat input of 75 kJ / cm, and the tensile strength of the weld metal reaches 650 MPa, which meets the requirements of relevant domestic standards / specifications, and has sufficient impact absorption energy margin. At the same time, the welding process performance is stable under a high heat input of 75 kJ / cm, the molten pool has good fluidity, the deposited metal is aesthetically pleasing, and the crack resistance is excellent.

[0051] In this invention, the method for preparing the 650MPa grade multi-wire submerged arc welding material suitable for 75kJ / cm heat input welding preferably includes the following steps:

[0052] (1) The raw materials are melted and cast in sequence to obtain ingots;

[0053] (2) The ingot obtained in step (1) is forged, rolled, drawn and post-treated in sequence to obtain a 650MPa grade multi-wire submerged arc welding material suitable for welding with a heat input of 75kJ / cm.

[0054] The present invention preferably involves melting and casting the raw materials sequentially to obtain ingots.

[0055] In this invention, the raw materials preferably include one or more of the following: industrial pure iron, carbon raiser, metallic manganese, metallic chromium, electrolytic nickel, ferromolybdenum, ferrotitanium, ferrovanadium, ferroboron, and metallic lanthanum, as well as ferrosilicon, magnesium alloys, and zirconium alloys. This invention does not have special requirements regarding the source of the raw materials; any commercially available materials in the art that can be used and whose usage can be calculated according to elemental ratios are acceptable.

[0056] In this invention, the preferred melting temperature is 1500–1600°C. This invention does not have special requirements for the melting time, as long as the raw materials are sufficiently melted and uniformly melted at the specified melting temperature.

[0057] In this invention, the casting temperature is preferably 1450–1550°C. By controlling the casting temperature within this range, this invention can reduce casting defects in the ingot and ensure a uniform ingot structure.

[0058] After obtaining the ingot, the present invention preferably performs forging, rolling, drawing and post-treatment on the ingot in sequence to obtain a 650MPa grade multi-wire submerged arc welding material suitable for welding with a heat input of 75kJ / cm.

[0059] In this invention, the initial forging temperature is preferably ≥1150℃; the final forging temperature is preferably ≥970℃. By controlling the forging temperature within the above range, this invention can ensure that the ingot has low deformation resistance, achieve sufficient deformation, effectively close casting defects, and achieve preliminary grain refinement.

[0060] In this invention, the rolling temperature is preferably 1100–1200°C. By controlling the rolling temperature within this range, this invention enables the welding material to have a denser microstructure and further achieves grain refinement.

[0061] In this invention, the drawing process preferably includes sequentially performing a first pickling, borax treatment, rough drawing, a first fine drawing, a second pickling, and a second fine drawing. This invention does not impose special requirements on the specific parameters of the various operations in the drawing process; conventional drawing operations in the art are sufficient to ensure that the dimensions of the welding material meet the usage requirements.

[0062] In this invention, the post-processing preferably includes sequential electroless copper plating, layer winding, and packaging. This invention does not have special requirements for the specific operations of the electroless copper plating and layer winding, as long as the copper plating layer thickness and the required solder material morphology are achieved.

[0063] The preparation method provided by this invention produces a 650MPa grade multi-wire submerged arc welding material suitable for welding with a heat input of 75kJ / cm. The material has a uniform and dense microstructure and exhibits more stable welding performance when used for multi-wire submerged arc welding with a heat input of 75kJ / cm.

[0064] The present invention also provides a welding method for the welding materials described in the above technical solution, comprising: performing multi-wire submerged arc welding on the base metal with welding materials and sintering flux under a heat input of 75 kJ / cm to obtain a welded part.

[0065] In this invention, the basicity of the sintering flux is preferably 2.2 ≤ B. ⅡW ≤2.5. By employing the above-mentioned types of sintering flux, this invention can more effectively achieve smokeless, odorless, arc-free, and spatter-free welding, ensuring that the weld metal has good mechanical properties and surface quality.

[0066] In this invention, the base metal is preferably made of Q370qE, Q420qE, or Q500qE. By selecting base metals of these types, this invention ensures that the mechanical properties of the weld metal obtained after welding with the welding material match the mechanical properties of the base metal.

[0067] In this invention, the preferred bevel type for the multi-wire submerged arc welding is a 30-60° V-groove or a 30-60° double V-groove. By employing the above-mentioned bevel types, this invention is more conducive to obtaining cladding metal with stable connections and excellent mechanical properties.

[0068] In this invention, the welding position for multi-wire submerged arc welding is preferably horizontal or horizontal. By employing these welding positions, this invention facilitates more uniform heating of the molten metal, resulting in welds with excellent mechanical properties.

[0069] In this invention, the layer temperature of the multi-wire submerged arc welding is preferably ≤160℃, more preferably 80~160℃. By controlling the layer temperature of the multi-wire submerged arc welding within the above range, this invention can ensure more stable welding under conditions of high heat input, and the heat of the weld can be dissipated as quickly as possible, avoiding grain coarsening caused by residual welding heat.

[0070] The welding method provided by this invention is more conducive to ensuring stable welding quality and excellent mechanical properties at the weld joint of the welded parts.

[0071] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. 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.

[0072] Examples 1-8 and Comparative Examples 1-2

[0073] The elements and their mass percentages in the welding materials for 650MPa grade multi-wire submerged arc welding suitable for 75kJ / cm heat input welding provided in Examples 1-8 and the welding materials of Comparative Examples 1-2 are shown in Table 1. The surfaces of the welding materials with the above chemical compositions are all coated with a copper plating layer with a thickness of 0.10μm.

[0074] Table 1 shows the elements and their mass percentages (%) of the welding materials for 650MPa-grade multi-wire submerged arc welding suitable for 75kJ / cm heat input welding provided in Examples 1-8 and the welding materials of Comparative Examples 1-2.

[0075]

[0076] The specific preparation methods for 650MPa grade multi-wire submerged arc welding materials suitable for welding with a heat input of 75kJ / cm provided in Examples 1-8 are as follows:

[0077] (1) The raw materials are smelted and cast in sequence to obtain ingots; specifically: industrial pure iron, carbon raiser, ferrosilicon, metallic manganese, metallic chromium, electrolytic nickel, ferromolybdenum, ferrotitanium, ferrovanadium, ferroboron, magnesium alloy, zirconium alloy and metallic lanthanum are smelted at 1950℃ to obtain alloy liquid, and then the alloy liquid is cast at 1880℃ to obtain ingots.

[0078] (2) The ingot obtained in step (1) is sequentially forged, rolled, drawn, and post-treated to obtain a 650MPa grade multi-wire submerged arc welding material suitable for welding with a heat input of 75kJ / cm; specifically: the ingot obtained in step (1) is forged at an initial forging temperature of 1180℃ and a final forging temperature of 980℃ to obtain a 50×50mm square billet; then the billet is held at 1150℃ for 1 hour to reach the rolling temperature and rolled in 15 passes to obtain The wire rods are then subjected to pickling, borax treatment (neutralization and lubrication), and rough drawing in sequence. Precision drawing Pickling and fine drawing Surface chemical copper plating, layering, and packaging.

[0079] The preparation method of Comparative Example 1 is the same as that of Examples 1 to 8, omitting the raw materials such as ferromolybdenum, ferrotitanium, ferrovanadium, ferroboron, magnesium alloy, zirconium alloy and lanthanum in step (1). Other raw materials are added in proportion according to the element content in Table 1. The remaining technical features are the same as those of Examples 1 to 8.

[0080] The preparation method of Comparative Example 2 is the same as that of Examples 1 to 8, omitting the raw materials such as metallic chromium, ferromolybdenum, ferrovanadium, ferroboron, magnesium alloy, zirconium alloy and metallic lanthanum in step (1). Other raw materials are added in proportion according to the element content in Table 1. The remaining technical features are the same as those of Examples 1 to 8.

[0081] Application Examples 1-8 and Comparative Application Examples 1-2

[0082] Welding methods were employed using the 650MPa grade multi-wire submerged arc welding materials provided in Examples 1-8, suitable for welding with a heat input of 75kJ / cm, and the welding materials in Comparative Examples 1-2. The welding method involved using the 650MPa grade multi-wire submerged arc welding materials provided in Examples 1-8 and the welding materials in Comparative Examples 1-2, respectively, with sintered flux, to perform multi-wire submerged arc welding on the base metal under a heat input of 75kJ / cm, resulting in 10 sets of welded specimens (5 samples were taken from each set for performance testing). The welding method was performed according to the welding parameters in Table 2; the steel plate used was Q500qE high-performance steel plate with dimensions of 600×300×24mm, and the layer temperature was controlled at 100℃. Other parameters are shown in Table 2.

[0083] Table 2 Welding parameters for Application Examples 1-8 and Comparative Application Examples 1-2

[0084]

[0085] After the above 10 groups of test pieces passed visual inspection and ultrasonic flaw detection, samples were taken from the weld metal of the welded parts, and the chemical composition of the weld metal was examined using a direct-reading spectrometer. The results are shown in Table 3. The tensile properties and -40℃ low-temperature impact properties of the weld metal of the 10 groups of test pieces were tested, and the results are shown in Table 4.

[0086] Table 3 shows the chemical composition and mass percentage (%) of the weld deposited metal of 10 groups of welded specimens obtained after welding in Application Examples 1-8 and Comparative Application Examples 1-2, with the balance being Fe.

[0087]

[0088]

[0089] Table 4 shows the mechanical properties of the weld metal from 10 groups of welded specimens in Application Examples 1-8 and Comparative Application Examples 1-2.

[0090]

[0091] As can be seen from Tables 3 and 4, the alloy composition of the weld metal of the specimens obtained by welding with the welding materials provided by the present invention all meet the requirements of the control relationship 0.72≤α≤1.33, 87.41≤β≤124.36, and 655.69≤γ≤772.68. However, the alloy composition of the weld metal of the comparative application examples 1 to 2 does not meet the above three control relationships. Meanwhile, the weld metal deposited in Examples 1-8 of this invention exhibits a yield strength of 546-595 MPa, a tensile strength of 664-740 MPa, an elongation of 20-24%, and an impact absorption energy (KV2) at -40℃ of 120-144 J. These properties demonstrate excellent overall mechanical performance, meeting relevant technical requirements with a significant margin of safety. In contrast, the weld metal deposited using the welding materials provided in Examples 1-2 exhibits a yield strength of 470-485 MPa, a tensile strength of 620-631 MPa, an elongation of 21-24%, and an impact absorption energy (KV2) at -40℃ of 29-34 J, all lower than the mechanical properties of the weld metal deposited in Examples 1-8 of this invention. Therefore, the weld metal deposited by the welding wire of this invention possesses significant advantages in terms of mechanical properties.

[0092] The microstructure of the weld metal obtained by welding under a heat input of 75 kJ / cm in Application Example 1 of this invention was observed using scanning electron microscopy. The obtained SEM image is shown below. Figure 1 As shown.

[0093] Depend on Figure 1 As can be seen, the microstructure of the weld metal in Application Example 1 of the present invention is mainly composed of uniformly distributed fine needle-like ferrite and granular bainite, and the structure is uniform and dense.

[0094] The microstructure of the weld metal obtained by welding under a heat input of 75 kJ / cm in Comparative Application Example 1 of this invention was observed using scanning electron microscopy. The obtained SEM images are shown below. Figure 2 As shown.

[0095] Depend on Figure 2 It can be seen that the microstructure of the weld metal obtained by welding the welding material provided in Comparative Example 1 with a welding heat input of 75 kJ / cm is mainly composed of coarse granular bainite and a small amount of acicular ferrite, and the distribution is uneven.

[0096] In summary, the welding material provided by this invention is suitable for welding with a high heat input of 75 kJ / cm, and the tensile strength of the weld metal reaches 650 MPa, meeting the requirements of relevant domestic standards / specifications, with sufficient impact absorption energy margin; at the same time, the welding process performance is stable under a high heat input of 75 kJ / cm, the molten pool has good fluidity, the deposited metal is aesthetically pleasing, and the crack resistance is excellent.

[0097] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A welding material for 650MPa grade multi-wire submerged arc welding suitable for welding with a heat input of 75kJ / cm, characterized in that, The composition includes the following elements by mass percentage: C: 0.08~0.12%, Si: ≤0.09%, Mn: 1.70~1.95%, Cr: 0.30~0.45%, Ni: 0.05~0.50%, Mo: 0.40~0.58%, Ti: 0.13~0.24%, V: 0.04~0.05%, B: 0.0005~0.0030%, Mg: ≤0.005%, Zr: ≤0.020%, La: ≤0.030%, P: ≤0.012%, S: ≤0.005%, Pb+Sn+As+Sb+Bi: ≤0.008%, and balance Fe; The mass percentages of the elements in the welding material have the following relationships: 0.72≤α≤1.33; 87.41≤β≤124.36; 655.69≤γ≤772.68; where, α=(62.17Si+19.33Mn+25.01Zr) / (45.33Cr+58.31Ni+20.32Mo); β=42.56Mn+75.88Ti+123.28V+520.16B+191.14Mg+482.66La; γ=405.54+105.14C+92.35Mn+54.06Cr+88.72Ni+109.86Mo+153.61Ti+97.88Zr.

2. The welding material as described in claim 1, characterized in that, The surface of the welding material is also coated with a copper plating layer.

3. The welding material as described in claim 2, characterized in that, The thickness of the copper plating layer is 0.08~0.12μm.

4. The welding method of the welding material as described in any one of claims 1 to 3, characterized in that, include: The base metal is subjected to multi-wire submerged arc welding with welding materials and sintered flux under a heat input of 75 kJ / cm to obtain the welded part.

5. The welding method as described in claim 4, characterized in that, The sintering flux has a basicity of 2.2≤B IIW ≤2.

5.

6. The welding method as described in claim 4, characterized in that, The base metal is made of materials including Q370qE, Q420qE, or Q500qE.

7. The welding method as described in claim 4, characterized in that, The bevel type of the multi-wire submerged arc welding is a 30~60° V-groove or a 30~60° double V-groove.

8. The welding method as described in claim 4, characterized in that, The welding position for the multi-wire submerged arc welding is either horizontal or vertical.

9. The welding method as described in claim 4, characterized in that, The layer temperature of the multi-wire submerged arc welding is ≤160℃.

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