A submerged arc welding wire suitable for high heat input welding of 50~200kJ / cm and its application

Abstract

This invention provides a submerged arc welding wire suitable for high heat input welding of 50–200 kJ / cm and its application, belonging to the field of welding materials technology. The submerged arc welding wire provided by this invention comprises the following chemical composition: C: 0.04–0.10%, Si≤0.09%, Mn: 2.0–2.25%, P≤0.012%, S≤0.005%, Ni: 1.05–1.65%, Mo: 0.4–0.58%, Ti: 0.11–0.24%, Cr≤0.015%, Re≤0.030%, Al≤0.05%, Zr≤0.015%, (Pb+Sn+As+Sb+Bi)≤0.011%, and the balance Fe. The submerged arc welding wire provided by this invention meets the requirements for the mechanical properties of the deposited metal at a heat input of 50–200 kJ / cm, and is applicable to the production of large welded structural components and high-efficiency welding manufacturing.

Description

Technical Field

[0001] This invention relates to the field of welding materials technology, and in particular to a submerged arc welding wire suitable for welding with a high heat input of 50-200 kJ / cm and its application. Background Technology

[0002] Long-span, heavy-load steel bridges commonly utilize thick-gauge steel beams, typically accounting for 40% of all structural components. To drive the steel industry towards efficient and intelligent manufacturing, and to improve welding efficiency for long-span, thick-gauge bridge structural components in both horizontal and vertical positions, while simultaneously shortening manufacturing time and reducing costs, the development of high-heat-intensity welding technology is urgently needed. Currently, if steel structure manufacturers use ordinary welding materials with high heat input to improve production efficiency, a sharp decrease in the toughness of the weld metal occurs, making it difficult to ensure the match between the mechanical properties of the weld metal and the high welding heat input. This is because as the welding heat input increases, the cooling rate of the weld zone decreases, and the weld metal microstructure tends to coarsen. Currently, most welding materials used in China for high heat input are imported, resulting in high costs. Therefore, developing efficient and high-performance welding materials offers advantages such as high production efficiency, energy saving, aesthetically pleasing results, low pollution, and ease of automation, making it a promising welding material with excellent development prospects.

[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. Its key feature is the addition of 0.01-0.05% Ti to form TiN, which pins austenite grain boundaries and prevents austenite grain growth. On the other hand, the addition of alloying elements such as Si, Mn, Ti, Al, Ce, and Mg promotes the formation of high-melting-point composite oxide inclusions of Si, Mn, Ti, Al, Ce, and Mg, thus promoting the formation of acicular ferrite. However, during high heat input welding (greater than 50 kJ / cm), Ti burn-off is severe, and the 0.01-0.05% titanium element transitions to a relatively small amount in the weld metal. Furthermore, in the embodiments, butt joint tests were conducted using high heat input welding. The weld metal fusion ratio resulting from high heat input welding is relatively large, and the effective components of the weld metal will be further diluted. Therefore, in the embodiments, a low value was observed in the -40°C low-temperature impact test at the weld center.

[0004] Chinese invention patent application CN200910046732.3 discloses a "high-toughness submerged arc welding wire" with moderate strength, high impact toughness, and high heat input resistance. It effectively improves low-temperature toughness, high heat input resistance, and yield strength and tensile strength by optimizing carbon content, controlling the maximum upper limit of silicon content, and combining it with a Mn-Ni system. However, in high-heat-input welding processes, the grain growth trend is more pronounced, and simply adding Ni to refine the ferrite phase grains and improve toughness is insufficient. Furthermore, adding too much Ni would increase the cost of welding wire smelting. Similarly, this invention is applicable to welding heat inputs of 30–40 kJ / cm, which is still somewhat different from high-heat-input welding.

[0005] Chinese invention patent application CN92105621.4 discloses a "low-carbon microalloyed submerged arc welding wire," characterized by the addition of 1.2-1.6% Mn and 0.2-0.4% Mo to improve weld strength through solid solution strengthening; and the addition of 0.02-0.08% Ti and 0.001-0.008% B to improve weld toughness through a composite effect, wherein Ti can also combine with free N. While this invention indicates its applicability to high heat input and high-speed welding, it does not specify the welding heat input. If this welding wire is used under high heat input welding conditions (>50 kJ / cm), the trace amounts of Ti and B will be significantly burned off, resulting in a small transition amount. Furthermore, the welding wire does not contain Ni, which has a relatively stable transition coefficient. Under high heat input welding conditions, the mechanical properties of the weld, especially the low-temperature impact toughness of the joint, are difficult to guarantee.

[0006] Chinese invention patent application CN01135349.X discloses a complete technology for "high heat input submerged arc welding joint, its manufacturing method, and the welding wire and flux used". The key feature is that the welding wire for high heat input submerged arc welding is composed of C: 0.03–0.10%, N: ≤0.0035%, Si: ≤0.4%, Mn: 1.0–2.5%, and Ti above 0.03%, satisfying a Ti / N ratio of 15–50. The welding wire composition also contains one or more of Mo, Nb, B, and Ni, and the weld metal composition of the joint must satisfy 0.6 ≤ B / N ≤ 1.2, and the amount of grain boundary ferrite in the weld metal must be controlled to be below 10.0% of the area. This invention patent technology is complex, has high requirements, and is difficult to implement. Furthermore, although the submerged arc welding wire of this invention can be used for welding under a high heat input of 150 kJ / cm, the examples only provide the low-temperature impact toughness at 0℃ and -20℃, and fail to provide the low-temperature impact toughness value required for Grade E steel at -40℃.

[0007] Chinese invention patent application CN200710139338.5 discloses a "submerged arc welding wire for X80 pipeline steel" using a Mn-Mo-Ti-B system. It adds 1.5–1.8% Mn to obtain strength and toughness, 0.3–0.4% Mo to ensure strength and promote ferrite formation, and 0.1–0.2% Ti to ensure high toughness of the weld metal. Additionally, 0.004–0.008% B is added to ensure strength and promote the development of acicular ferrite microstructure in the weld, thus improving toughness. This welding wire is suitable for welding X80 pipeline steel, and the quality of its weld and heat-affected zone meets relevant standards. However, if this welding wire is used in high heat input welding (greater than 50 kJ / cm), the 0.25–0.35% Si content in the wire, combined with Si elements transferred from the base metal and submerged arc flux, can easily result in a high Si content in the weld metal, which will affect the low-temperature toughness of the weld metal. Furthermore, since the welding wire does not contain Ni, which has a relatively stable transition coefficient, it is difficult to guarantee the mechanical properties of the weld, especially the low-temperature impact toughness of the joint, under high heat input welding conditions.

[0008] To improve the welding efficiency of large steel structures such as bridges, selecting superior submerged arc welding wire is crucial for further improving welding efficiency, reducing costs, enhancing the mechanical properties of welded joints, and replacing imported products. Therefore, developing a submerged arc welding wire suitable for Q370–Q420qE grade welding heat inputs of 50–200 kJ / cm² while meeting the mechanical property requirements of relevant standards and specifications has become a pressing problem in this field. Summary of the Invention

[0009] The purpose of this invention is to provide a submerged arc welding wire suitable for welding with a high heat input of 50-200 kJ / cm and its application. The submerged arc welding wire provided by this invention achieves various specifications for the mechanical properties of the deposited metal within the heat input range of 50-200 kJ / cm, that is, it obtains good strength and plasticity while also having excellent low-temperature impact toughness. It can be applied to the production and efficient welding manufacturing of large welded structural components in industries such as bridges, ships and buildings.

[0010] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0011] This invention provides a submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm, comprising the following chemical composition by mass percentage: C: 0.04-0.10%, Si≤0.09%, Mn: 2.0-2.25%, P≤0.012%, S≤0.005%, Ni: 1.05-1.65%, Mo: 0.4-0.58%, Ti: 0.11-0.24%, Cr≤0.015%, Re≤0.030%, Al≤0.05%, Zr≤0.015%, (Pb+Sn+As+Sb+Bi)≤0.011%, and the balance Fe;

[0012] The chemical composition ratios of Si, Mn, Cr, Ni, Mo, and Ti in the submerged arc welding wire conform to the following: 0.83≤Ф≤2.13; Ф=(Ni+6Ti+2Mo) / (8Si+Mn+3Cr);

[0013] The chemical composition of the submerged arc welding wire conforms to the following: 550.8 ≤ θ ≤ 650.7; strength factor θ = 9.8 × (36.69 + 138.6 W). C +4.8W Mn +11.9W Cr +2.21W Ni +6.642W Mo +0.96W Ti ).

[0014] Preferably, by mass percentage, it comprises the following chemical composition: C: 0.04–0.10%, Si ≤ 0.08%, Mn: 2.0–2.25%, P ≤ 0.010%, S ≤ 0.005%, Ni: 1.15–1.55%, Mo: 0.4–0.58%, Ti: 0.12–0.22%, Cr ≤ 0.015%, Re ≤ 0.030%, Al ≤ 0.05%, Zr ≤ 0.015%, (Pb+Sn+As+Sb+Bi) ≤ 0.011%, and the balance Fe.

[0015] Preferably, by mass percentage, it comprises the following chemical composition: C: 0.04–0.10%, Si ≤ 0.08%, Mn: 2.05–2.25%, P ≤ 0.010%, S ≤ 0.005%, Ni: 1.25–1.55%, Mo: 0.4–0.55%, Ti: 0.14–0.20%, Cr ≤ 0.015%, Re ≤ 0.030%, Al ≤ 0.05%, Zr ≤ 0.015%, (Pb+Sn+As+Sb+Bi) ≤ 0.010%, and the balance Fe.

[0016] Preferably, the chemical composition ratio of the submerged arc welding wire conforms to the following: 560≤θ≤640.

[0017] Preferably, the chemical composition ratio of the submerged arc welding wire conforms to the following: 570≤θ≤630.

[0018] Preferably, the chemical composition ratio of Si, Mn, Cr, Ni, Mo and Ti in the submerged arc welding wire is: 0.85≤Ф≤2.1.

[0019] Preferably, the chemical composition ratio of Si, Mn, Cr, Ni, Mo and Ti in the submerged arc welding wire is: 0.9≤Ф≤2.0.

[0020] Preferably, the submerged arc welding wire further includes a copper plating layer disposed on its surface, the thickness of which is 0.19–0.23 μm.

[0021] This invention provides the application of the submerged arc welding wire, which is suitable for high heat input welding of 50-200 kJ / cm, in submerged arc welding and flux copper backing method.

[0022] Preferably, the submerged arc welding wire is used in the production and efficient welding manufacturing of large welded structural components in the bridge, shipbuilding and construction industries.

[0023] This invention provides a submerged arc welding wire suitable for high heat input welding of 50–200 kJ / cm, comprising the following chemical composition by mass percentage: C: 0.04–0.10%, Si ≤ 0.09%, Mn: 2.0–2.25%, P ≤ 0.012%, S ≤ 0.005%, Ni: 1.05–1.65%, Mo: 0.4–0.58%, Ti: 0.11–0.24%, Cr ≤ 0.015%, Re ≤ 0.030%, Al ≤ 0.0 5%, Zr≤0.015%, (Pb+Sn+As+Sb+Bi)≤0.011% and balance Fe; the chemical composition ratio of Si, Mn, Cr, Ni, Mo and Ti in the submerged arc welding wire conforms to: 0.83≤Ф≤2.13; Ф=(Ni+6Ti+2Mo) / (8Si+Mn+3Cr); the chemical composition ratio of the submerged arc welding wire conforms to: 550.8≤θ≤650.7; strength factor θ=9.8×(36.69+138.6W) C +4.8W Mn +11.9W Cr +2.21W Ni +6.642W Mo +0.96W TiThe submerged arc welding wire provided by this invention contains Ni, an austenite-stabilizing element that can dissolve in ferrite and austenite. It can suppress the formation of proeutectoid ferrite by lowering the phase transformation temperature, promote the formation of acicular ferrite, and thus improve microstructure refinement. Ti can form complex oxide inclusions, promoting intragranular nucleation and suppressing the formation of grain boundary ferrite. Furthermore, Ti has a small atomic mass and can form TiC with C, fixing a certain amount of C atoms. The rapid migration rate of TiC effectively prevents the formation of MA components. While Mo can improve weld strength, it has a negative impact on MA components. The formation is favorable; Si increases the phase transformation point, coarsens the weld microstructure, and also hinders carbide formation, which is beneficial to the formation of MA components; the increase of Mn will lead to an increase in hard phases in the microstructure due to segregation; Cr will enrich C in austenite, which is beneficial to the formation of MA components; by using the Mn-Ni-Mo-Ti alloy system and adding appropriate amounts of Zr and Re, the strength and toughness of the weld metal can be balanced under a wide range of heat input welding conditions; the solid solution strengthening effect of Mn and Mo is used to compensate for the element burn-off caused by high heat input welding. The amount of Ti is beneficial for promoting the acicular ferrite microstructure of the weld and improving toughness; the addition of Ni can improve the toughness of the weld metal, especially the low-temperature impact toughness, and reduce the brittle transition temperature; in addition, appropriate amounts of Zr and Re can modify inclusions, change their morphology, and improve the metallurgical quality of the weld metal; by adjusting the content of alloying elements such as Ni, Mo, Cr, Si, Ti, and Mn, the microstructure can be refined, thereby controlling the degree of coarsening of the weld microstructure; by adjusting the transition allowance of each alloying element after high heat input welding burn-off and the transition allowance of each alloying element after high heat input welding burn-off, the weld metal can be refined. The strength increment caused by chemical composition is combined with the influence of strengthening and toughening methods such as solid solution strengthening, dislocation strengthening, precipitation and dispersion strengthening, and grain boundary strengthening on the properties of metallic materials, as well as the precipitation strengthening effect of carbides or nitrides formed by trace elements such as Ti and B in the weld on dislocation pinning. Thus, the above relationship is obtained. By controlling the contents of C, Mn, Cr, Ni, Mo and Ti to satisfy the above relationship, the deposited metal obtained by submerged arc welding wire under a heat input of 50 to 200 kJ / cm has excellent comprehensive properties, with high tensile strength and low-temperature impact toughness. The results of the embodiments show that the submerged arc welding wire provided by the present invention has excellent comprehensive performance of the deposited metal in the range of heat input of 50 to 200 kJ / cm, with high tensile strength and low-temperature impact toughness, yield strength Rp0.2 / MPa: 435 to 520 MPa, tensile strength Rm / MPa: 545 to 650 MPa, elongation A / %: 22 to 24.5%, and impact absorption energy Akv-40℃ / J: 85 to 179 J. It can be applied to the production and efficient welding manufacturing of large welded structural components in industries such as bridges, ships and buildings. Attached Figure Description

[0024] Figure 1 This is a microstructure diagram of the weld seam obtained in Example 1. Detailed Implementation

[0025] This invention provides a submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm, comprising the following chemical composition by mass percentage: C: 0.04-0.10%, Si≤0.09%, Mn: 2.0-2.25%, P≤0.012%, S≤0.005%, Ni: 1.05-1.65%, Mo: 0.4-0.58%, Ti: 0.11-0.24%, Cr≤0.015%, Re≤0.030%, Al≤0.05%, Zr≤0.015%, (Pb+Sn+As+Sb+Bi)≤0.011%, and the balance Fe;

[0026] The chemical composition ratios of Si, Mn, Cr, Ni, Mo, and Ti in the submerged arc welding wire conform to the following: 0.83≤Ф≤2.13; Ф=(Ni+6Ti+2Mo) / (8Si+Mn+3Cr);

[0027] The chemical composition of the submerged arc welding wire conforms to the following: 550.8 ≤ θ ≤ 650.7; strength factor θ = 9.8 × (36.69 + 138.6 W). C +4.8W Mn +11.9W Cr +2.21W Ni +6.642W Mo +0.96W Ti ).

[0028] By mass percentage, the submerged arc welding wire provided by this invention, suitable for welding with a high heat input of 50–200 kJ / cm, comprises C: 0.04–0.10%, preferably 0.05–0.10%, and more preferably 0.06–0.09%. In this invention, carbon has the effect of increasing the strength of the deposited metal, while also significantly reducing its toughness and crack resistance. To improve toughness and crack resistance, the carbon content should be as low as possible. However, carbon is significantly lost during submerged arc welding; therefore, to ensure appropriate strength and minimize the impact of carbon on toughness and crack resistance, the carbon content is limited to the range of 0.04–0.10%.

[0029] By mass percentage, the submerged arc welding wire provided by this invention, suitable for welding with a high heat input of 50–200 kJ / cm, contains Si ≤0.09%, preferably ≤0.08%. In this invention, the influence of silicon on the weld microstructure and properties is mainly manifested through its interaction with oxygen in the weld metal. Silicon and oxygen can combine to form silicates and their complexes, which are nucleating agents for acicular ferrite (AF). When manganese and silicon are present simultaneously, silicon acts as a deoxidizer. As the content of manganese and silicon increases, the phase transformation temperature of continuous cooling gradually decreases, and the microstructure is refined, thereby affecting the microstructure and properties of the weld metal. At the same time, the silicon in the weld metal is usually transitioned by the flux, so the silicon content in the welding wire composition is limited to ≤0.09%.

[0030] By mass percentage, the submerged arc welding wire provided by this invention, suitable for high heat input welding of 50–200 kJ / cm, comprises Mn: 2.0–2.25%, preferably 2.05–2.25%. In this invention, manganese is a crucial deoxidizing element, effectively reducing the oxygen content in the weld metal. Simultaneously, Mn improves hardenability, refines the microstructure, and enhances the weld metal strength through solid solution strengthening. When the Mn content is below 2.0%, the weld metal strength does not meet requirements and is not conducive to preventing welding hot cracking. When the Mn content is above 2.25%, martensitic structures are easily formed, leading to a significant decrease in toughness. Considering the substantial burn-off of manganese during high heat input welding, the manganese content in the welding wire is controlled within the range of 2.0–2.25%.

[0031] By mass percentage, the submerged arc welding wire provided by this invention, suitable for welding with a high heat input of 50–200 kJ / cm, includes P ≤ 0.010% and S ≤ 0.005%. In this invention, P and S are impurity elements that have a detrimental effect on the toughness of the weld metal. Excessive content can easily cause cracks in the weld. Their content should be reduced as much as possible, especially P, because the use of flux during submerged arc welding will increase the P content in the weld metal. Therefore, the P content in the welding wire is limited to below 0.010%, and the S content is limited to below 0.005%.

[0032] The submerged arc welding wire provided by this invention, suitable for high heat input welding of 50–200 kJ / cm, comprises Ni: 1.05–1.65%, preferably 1.15–1.55%, and more preferably 1.25–1.55% by mass percentage. The main function of adding Ni to the submerged arc welding wire in this invention is to improve the low-temperature toughness of the weld metal. Simultaneously, it utilizes its solid solution strengthening effect to improve the strength of the weld metal. The mechanism by which Ni improves low-temperature toughness is through toughening the ferrite matrix and lowering its brittle transition temperature. Both Ni and Mn are austenite stabilizing elements, and both can lower the austenite phase transformation temperature by appropriate addition. However, their effects on impact toughness are not entirely the same, so they can be added simultaneously. In high heat input welding, the low-temperature toughness of the weld metal decreases significantly, and Ni also suffers some burn-off. Therefore, the amount of Ni added should be increased. Thus, the Ni content in the welding wire composition is controlled within the range of 1.05–1.65%.

[0033] By mass percentage, the submerged arc welding wire provided by this invention, suitable for welding with a high heat input of 50–200 kJ / cm, comprises Mo: 0.4–0.58%, preferably 0.4–0.55%. The addition of Mo to the submerged arc welding wire in this invention can improve the strength and low-temperature impact toughness of the weld metal. Simultaneously, the added Mo can effectively reduce the phase transformation temperature of the weld metal during the post-weld cooling process, thereby refining the weld metal microstructure and simultaneously expanding the formation temperature range of acicular ferrite and bainite. The refinement of the submerged arc welding wire microstructure improves the strength of the weld metal, while the promotion of acicular ferrite improves the low-temperature impact toughness. Because Mo is relatively expensive and can easily increase production costs, the Mo content in the welding wire composition is controlled within the range of 0.4–0.58%.

[0034] The submerged arc welding wire provided by this invention, suitable for high heat input welding of 50–200 kJ / cm, comprises Ti as a percentage by mass: 0.11–0.24%, preferably 0.12–0.22%, and more preferably 0.14–0.20%. The main function of adding Ti to the submerged arc welding wire is that the dispersed oxides and nitrides formed by Ti effectively inhibit austenite grain growth. Furthermore, when its volume content increases within an appropriate range, it significantly promotes the formation of acicular ferrite in the weld metal. Simultaneously, the inclusion of Ti in composite oxides with Si, Mn, Al, and Mg is beneficial for the nucleation and growth of acicular ferrite, improving the low-temperature toughness of the weld metal under high heat input. In high heat input welding, Ti burn-off is severe, so the amount of Ti added should be increased; therefore, the Ti content in the welding wire composition is controlled within the range of 0.11–0.24%.

[0035] By mass percentage, the submerged arc welding wire provided by this invention, suitable for welding with a high heat input of 50–200 kJ / cm, contains Cr ≤ 0.015%, preferably 0.010–0.015%. In this invention, Cr is one of the important strengthening elements. A certain amount of Cr can refine the grains and increase the strength of the metal. However, if the content is too high, it will cause carbide segregation, increase the sensitivity to welding cracks, and reduce the toughness and plasticity of the deposited metal. Therefore, the Cr content in the welding wire composition is controlled within the range of ≤ 0.015%.

[0036] By mass percentage, the submerged arc welding wire provided by this invention, suitable for high heat input welding of 50–200 kJ / cm, contains Re ≤ 0.030%, preferably 0.01–0.03%, and more preferably 0.015–0.025%. This invention does not specifically limit the type of Re; any rare earth element well-known to those skilled in the art can be used. Adding trace amounts of rare earth elements to the welding wire can effectively reduce the content of inclusions such as oxides, nitrides, and sulfides, and change the morphology of inclusions. Simultaneously, rare earth elements can improve the fluidity of the weld pool, further reduce the gas and inclusion content in the weld, and improve the metallurgical quality of the deposited metal. Therefore, the Re content in the welding wire composition is controlled within the range of ≤ 0.03%.

[0037] By mass percentage, the submerged arc welding wire provided by this invention, suitable for welding with high heat input of 50–200 kJ / cm, contains Al ≤ 0.05%, preferably ≤ 0.04%. In this invention, aluminum is a ferrite-forming element with a strong affinity for oxygen. When the weld contains a small amount of Al₂O₃, the resulting composite inclusions can act as nucleation sites for ferrite (AF), effectively refining the weld microstructure. Simultaneously, Al has a stronger affinity for oxygen than Ti; therefore, excessive Al content can affect the formation and distribution of Ti oxides. Furthermore, excessive Al may excessively shrink the austenite region, delaying or even hindering phase transformation and promoting the formation of large amounts of blocky ferrite. In addition, the hardness and strength of the weld increase with increasing Al content, while the impact toughness decreases. Regarding weld toughness, the Al content should be as low as possible; therefore, this invention controls the Al content in the welding wire composition to ≤ 0.05%.

[0038] By mass percentage, the submerged arc welding wire provided by this invention, suitable for welding with high heat input of 50–200 kJ / cm, contains Zr ≤ 0.015%, preferably ≤ 0.013%. In this invention, Zr can form high-melting-point inclusions in the weld, effectively refining inclusions in the weld metal and promoting MnS spheroidization. Composite inclusions formed by Zr with other elements also facilitate the formation of AF in the weld metal, improving its toughness. This invention controls the Zr content in the welding wire composition to ≤ 0.015%.

[0039] The submerged arc welding wire provided by this invention, suitable for high heat input welding of 50-200 kJ / cm, comprises (Pb+Sn+As+Sb+Bi)≤0.011%, preferably ≤0.01%, by mass percentage. In this invention, Pb, Sn, As, Sb and Bi are all harmful elements, so their total mass percentage content needs to be strictly controlled within the range of ≤0.011%.

[0040] By weight percentage, the submerged arc welding wire provided by this invention, suitable for high heat input welding of 50–200 kJ / cm, includes the balance Fe. In this invention, the Fe is a matrix element.

[0041] In this invention, the chemical composition ratio of Si, Mn, Cr, Ni, Mo, and Ti in the submerged arc welding wire conforms to: 0.83≤Ф≤2.13, preferably 0.85≤Ф≤2.1, and more preferably 0.9≤Ф≤2.0; wherein Ф=(Ni+6Ti+2Mo) / (8Si+Mn+3Cr). This invention achieves the purpose of refining the microstructure by adjusting the content of alloying elements Ni, Mo, Cr, Si, Ti, and Mn, thereby controlling the degree of coarsening of the weld microstructure.

[0042] In this invention, the chemical composition ratio of the submerged arc welding wire conforms to 550.8≤θ≤650.7, preferably 560≤θ≤640, and more preferably 570≤θ≤630; wherein, θ=9.8×(36.69+138.6W) C +4.8W Mn +11.9W Cr +2.21W Ni +6.642W Mo +0.96W Ti This invention combines the transition allowance of each alloying element after high heat input welding burn-off with the strength increment caused by chemical composition. It also considers the influence of strengthening and toughening methods such as solid solution strengthening, dislocation strengthening, precipitation and dispersion strengthening, and grain boundary strengthening on the properties of metallic materials, as well as the precipitation strengthening effect of carbides or nitrides formed by trace elements such as Ti and B in the weld on dislocation pinning. Thus, the above-mentioned relationship is obtained. By controlling the contents of C, Mn, Cr, Ni, Mo, and Ti to satisfy the above relationship, the deposited metal obtained by submerged arc welding wire under a heat input of 50-200 kJ / cm has excellent comprehensive properties, with high tensile strength and low-temperature impact toughness.

[0043] In this invention, the submerged arc welding wire preferably further includes a copper plating layer on its surface; the thickness of the copper plating layer is preferably 0.19–0.23 μm, more preferably 0.20–0.22 μm, and even more preferably 0.20–0.21 μm. This invention avoids internal elemental oxidation by providing a copper plating layer.

[0044] The submerged arc welding wire provided by this invention contains Ni, an austenite-stabilizing element that can dissolve in ferrite and austenite. It can suppress the formation of proeutectoid ferrite by lowering the phase transformation temperature, promoting the formation of acicular ferrite and thus refining the microstructure. Ti can form complex oxide inclusions, promoting intragranular nucleation and inhibiting the formation of grain boundary ferrite. Furthermore, Ti's small atomic mass allows it to form TiC with C, fixing a certain amount of C atoms. The rapid migration rate of TiC effectively prevents the formation of MA components. While Mo can improve weld strength, it is also beneficial for the formation of MA components. Si increases the phase transformation point, coarsening the weld microstructure, and also hinders carbide formation, thus promoting the formation of MA components. The increase in Mn content will... Segregation increases the hard phase in the microstructure; Cr enriches C in austenite, which is beneficial to the formation of MA components; using a Mn-Ni-Mo-Ti alloy system and adding appropriate amounts of Zr and Re elements, the strength and toughness of the weld metal are balanced under a wide range of heat input welding conditions; the solid solution strengthening effect of Mn and Mo is used to compensate for the strength loss caused by element burn-off after high heat input welding; an appropriate amount of Ti is beneficial to promoting the acicular ferrite microstructure of the weld and improving toughness; adding Ni can improve the toughness of the weld metal, especially the low-temperature impact toughness of the weld metal, and reduce the brittle transition temperature; in addition, appropriate amounts of Zr and Re elements can modify inclusions, change their morphology, and improve the metallurgical quality of the weld metal.

[0045] In this invention, the preferred method for preparing submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm includes: smelting and casting steel ingots according to the alloy composition of the submerged arc welding wire, then forging, rolling into wire rods, drawing into welding wires of the corresponding size, copper plating and polishing, and finally coiling and packaging into finished products. This invention does not impose specific limitations on the process parameters in the preparation method; they can be determined based on the technical knowledge of those skilled in the art. The alloy system of the submerged arc welding wire of this invention is reasonably controlled, and its wire rod smelting, rolling, and welding wire drawing processes are easy to implement, resulting in stable quality and suitability for large-scale application.

[0046] This invention provides the application of the submerged arc welding wire, which is suitable for high heat input welding of 50-200 kJ / cm, in submerged arc welding and flux copper backing method.

[0047] In this invention, the submerged arc welding wire is preferably matched with an Fe-containing basic sintered flux during application; the Fe-containing basic sintered flux is preferably a Fe-powder-MgO-SiO2-CaF2-Al2O3 system basic sintered flux. This invention does not have a specific limitation on the specific source of the Fe-containing basic sintered flux; commercially available products well-known to those skilled in the art can be used.

[0048] In this invention, the submerged arc welding is preferably a double-wire submerged arc automatic welding, a triple-wire submerged arc automatic welding, or a quadruple-wire submerged arc automatic welding.

[0049] In this invention, the submerged arc welding wire is preferably used in the production and efficient welding manufacturing of large welded structural components in the bridge, shipbuilding and construction industries, and is more preferably used for efficient welding of Q370 to Q420qE grade steel plates under a welding heat input of 50 to 200 kJ / cm.

[0050] The submerged arc welding wire provided by this invention has a suitable heat input range of 50–200 kJ / cm, and is compatible with Fe-containing alkaline sintered flux. During welding, it exhibits stable welding performance, good molten pool fluidity, aesthetically pleasing deposited metal formation, and excellent crack resistance. This submerged arc welding wire has a simple chemical composition, high deposition efficiency, excellent low-temperature toughness, and strong adaptability to various welding heat input ranges, making it suitable for the efficient welding and manufacturing of large steel structures in fields such as bridges, ships, and buildings.

[0051] 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.

[0052] Examples 1-3 and Comparative Examples 1-3

[0053] The chemical compositions of the submerged arc welding wires provided in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1:

[0054] Table 1. Chemical composition (wt.%) of the submerged arc welding wires provided in Examples 1-3 and Comparative Examples 1-3.

[0055]

[0056] The preparation methods of the submerged arc welding wires provided in Examples 1-3 and Comparative Examples 1-3 are as follows: Based on the precisely calculated welding wire composition ratio, raw materials with low P, S, gas and inclusion content are selected, the amount of alloy added is calculated, and welding wire steel is smelted in a 75kg vacuum induction furnace. After charging, melting and refining, the steel is cast into steel ingots after the composition is qualified. The steel ingots are forged into square billets and rolled into 8.5mm wire rods. The wire rods are then drawn into 5.0mm solid submerged arc welding wires through one coarse drawing and two fine drawing. The welding wire quality is stable. The surface of the welding wire is further coated with copper using a chemical copper plating method, with a copper plating thickness of 0.20μm, to obtain the submerged arc welding wire.

[0057] The submerged arc welding wires provided in Examples 1-3 and Comparative Examples 1-3 were subjected to single-wire deposited metal tests according to the welding process parameters in Table 2. The welding heat input was 50 kJ / cm, and the Fe powder-MgO-SiO2-CaF2-Al2O3 alkaline sintering flux was used for welding. The layer temperature was controlled to be no more than 160℃.

[0058] Table 2. Bevel type and process parameters for the single-wire metal deposition test.

[0059]

[0060] Examples 4-6 and Comparative Examples 4-6

[0061] The chemical compositions of the submerged arc welding wires provided in Examples 4-6 and Comparative Examples 4-6 are shown in Table 3:

[0062] Table 3. Chemical composition (wt.%) of the submerged arc welding wires provided in Examples 4-6 and Comparative Examples 4-6

[0063]

[0064] The preparation methods of the submerged arc welding wires provided in Examples 4-6 and Comparative Examples 4-6 are the same as those in Example 1.

[0065] The submerged arc welding wires provided in Examples 4-6 and Comparative Examples 4-6 were subjected to a double-wire deposited metal test according to the welding process parameters in Table 4. The welding heat input was 100 kJ / cm, and a specially formulated Fe powder-MgO-SiO2-CaF2-Al2O3 alkaline sintering flux was used for welding. The layer temperature was controlled to be no more than 160℃.

[0066] Table 4. Bevel type and process parameters for the single-wire metal deposition test.

[0067]

[0068] Examples 7-9 and Comparative Examples 7-9

[0069] The chemical compositions of the submerged arc welding wires provided in Examples 7-9 and Comparative Examples 7-9 are shown in Table 5:

[0070] Table 5. Chemical composition (wt.%) of the submerged arc welding wires provided in Examples 7-9 and Comparative Examples 7-9.

[0071]

[0072] The preparation methods of the submerged arc welding wires provided in Examples 7-9 and Comparative Examples 7-9 are the same as those in Example 1.

[0073] The submerged arc welding wires provided in Examples 7-9 and Comparative Examples 7-9 were subjected to a three-wire deposited metal test according to the welding process parameters in Table 6. The welding heat input was 200 kJ / cm, and a specially formulated Fe powder-MgO-SiO2-CaF2-Al2O3 alkaline sintering flux was used for welding. The layer temperature was controlled to be no more than 160℃.

[0074] Table 6. Bevel type and process parameters for the single-wire metal deposition test.

[0075]

[0076] Performance Testing: Samples were taken from the welded fusion metal, ensuring that the entire parallel length consisted of fusion metal. The sample size and test methods were performed according to GB / T 228. Impact test specimens were cut from the center of the fusion metal, with the longitudinal axis of the specimen perpendicular to the length of the fusion metal, the notched surface perpendicular to the fusion metal surface, and the notch axis located at the center of the fusion metal. The specimen size was 10×10×55mm, and the impact test method was performed according to GB / T 229. The tensile and impact test results of the fusion metal are shown in Table 7, with the values ​​in parentheses representing averages.

[0077] Table 7 shows the mechanical properties of the weld metal obtained from the submerged arc welding wires provided in Examples 1-9 and Comparative Examples 1-9.

[0078]

[0079]

[0080] As shown in Table 7, the submerged arc welding wire provided by this invention can meet various specifications for deposited metal within a heat input range of 50–200 kJ / cm, exhibiting excellent comprehensive performance, high tensile strength and low-temperature impact toughness, yield strength Rp0.2 / MPa: 435–520 MPa, tensile strength Rm / MPa: 545–650 MPa, elongation A / %: 22–24.5%, and impact absorption energy Akv-40℃ / J: 85–179 J. It can be applied to the production and efficient welding manufacturing of large welded structural components in industries such as bridges, ships, and buildings.

[0081] Figure 1 This is a microstructure image of the weld metal obtained in Example 1. (From...) Figure 1 It can be seen that the proportion of acicular ferrite in the weld metal formed by the welding wire provided by the present invention is not less than 80%, and the microstructure is uniformly distributed.

[0082] 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 submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm, comprising the following chemical composition by mass percentage: C: 0.04-0.10%, Si≤0.09%, Mn: 2.0-2.25%, P≤0.012%, S≤0.005%, Ni: 1.05-1.65%, Mo: 0.4-0.58%, Ti: 0.11-0.24%, Cr≤0.015%, Re≤0.030%, Al≤0.05%, Zr≤0.015%, (Pb+Sn+As+Sb+Bi)≤0.011% and balance Fe; The chemical composition ratios of Si, Mn, Cr, Ni, Mo, and Ti in the submerged arc welding wire conform to the following: 0.83≤Ф≤2.13; Ф=(Ni+6Ti+2Mo) / (8Si+Mn+3Cr); The chemical composition of the submerged arc welding wire conforms to the following: 550.8 ≤ θ ≤ 650.7; strength factor θ = 9.8 × (36.69 + 138.6 W). C +4.8W Mn +11.9W Cr +2.21W Ni +6.642W Mo +0.96W Ti ).

2. The submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm as described in claim 1, characterized in that, The chemical composition, by mass percentage, includes the following: C: 0.04–0.10%, Si ≤ 0.08%, Mn: 2.0–2.25%, P ≤ 0.010%, S ≤ 0.005%, Ni: 1.15–1.55%, Mo: 0.4–0.58%, Ti: 0.12–0.22%, Cr ≤ 0.015%, Re ≤ 0.030%, Al ≤ 0.05%, Zr ≤ 0.015%, (Pb+Sn+As+Sb+Bi) ≤ 0.011%, and the balance Fe.

3. The submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm as described in claim 2, characterized in that, The chemical composition, by mass percentage, includes the following: C: 0.04–0.10%, Si ≤ 0.08%, Mn: 2.05–2.25%, P ≤ 0.010%, S ≤ 0.005%, Ni: 1.25–1.55%, Mo: 0.4–0.55%, Ti: 0.14–0.20%, Cr ≤ 0.015%, Re ≤ 0.030%, Al ≤ 0.05%, Zr ≤ 0.015%, (Pb+Sn+As+Sb+Bi) ≤ 0.010%, and the balance Fe.

4. The submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm as described in claim 1, characterized in that, The chemical composition ratio of the submerged arc welding wire conforms to the following: 560≤θ≤640.

5. The submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm as described in claim 4, characterized in that, The chemical composition ratio of the submerged arc welding wire conforms to the following: 570≤θ≤630.

6. The submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm as described in claim 1, characterized in that, The chemical composition ratio of Si, Mn, Cr, Ni, Mo and Ti in the submerged arc welding wire conforms to the following: 0.85≤Ф≤2.

1.

7. The submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm as described in claim 1, characterized in that, The chemical composition ratio of Si, Mn, Cr, Ni, Mo and Ti in the submerged arc welding wire conforms to the following: 0.9≤Ф≤2.

0.

8. The submerged arc welding wire suitable for high heat input welding of 50-200 kJ / cm as described in claim 1, characterized in that, The submerged arc welding wire also includes a copper plating layer on its surface, the thickness of which is 0.19–0.23 μm.

9. The application of the submerged arc welding wire, as described in any one of claims 1 to 8, suitable for welding with a high heat input of 50 to 200 kJ / cm, in submerged arc welding and flux copper backing method.

10. The application according to claim 9, characterized in that, The submerged arc welding wire is used in the production and efficient welding manufacturing of large welded structural components in the bridge, shipbuilding and construction industries.

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