600MPa grade multi-wire submerged arc welding wire and wire suitable for 100kJ / cm high heat input welding

Abstract

This invention discloses a 600MPa grade multi-wire submerged arc welding wire suitable for welding with a high heat input of 100kJ / cm. The chemical composition of the wire, by mass percentage, includes: C: 0.07~0.12, Si≤0.09, Mn: 2.0~2.25, P≤0.012, S≤0.005, Ni: 0.05~0.5, Cr: 0.10~0.25, Mo: 0.2~0.38, Ti: 0.14~0.24, V: 0.03~0.04, B: 0.0005~0.0030, Zr≤0.015, rare earth La≤0.020, with the balance being Fe and unavoidable impurities. This invention also provides a welding wire based on the above-mentioned wire. The welding wire alloy system of this invention is rationally controlled, and its wire smelting, rolling, and welding wire drawing processes are easy to implement, resulting in stable quality and suitability for large-scale application.

Description

Technical Field

[0001] This invention belongs to the field of welding materials technology, specifically relating to a 600MPa grade multi-wire submerged arc welding pad and welding wire suitable for welding with a high heat input of 100 kJ / cm. Background Technology

[0002] In recent years, urban and rural transportation has developed rapidly, with bridge construction showing a particularly rapid pace, especially the planning and construction scale of large-span steel bridges such as those spanning rivers and seas. Among all the components used in large-span heavy-duty steel bridges, thick-gauge steel beams, widely used in large quantities, account for 40%. To improve the welding efficiency of large-span, thick-gauge bridge structural components at both horizontal and vertical positions, shorten manufacturing time, and reduce costs, thus promoting the steel industry towards efficient and intelligent manufacturing, high-heat welding technology urgently needs development. Currently, steel structure manufacturing enterprises use ordinary welding materials and high-heat welding to improve production efficiency, which leads to a decline in welding quality, resulting in problems such as a sharp decrease in the toughness of the weld metal and instability in the match between the high-heat input and the mechanical properties of the weld metal. This is because as the welding heat input increases, the cooling rate of the weld zone decreases, resulting in a coarser weld metal microstructure. Currently, most of the welding materials used in the high-heat field in China rely on imports, which are costly. For the reasons mentioned above, the development of efficient and high-performance welding materials has advantages such as high production efficiency, green energy saving, beautiful forming, low pollution and easy automation, and therefore has a good development prospect.

[0003] Chinese invention patent application CN97104393.0 discloses a low-alloy high-strength, high-toughness submerged arc welding wire. This wire achieves suitable weld strength by reducing C and Mn content, controlling Si content, lowering S and P content, and adding 0.2-0.5% Ni, 0.10-0.16% Ti, and 0.006-0.01% B, forming a Mn-Ni-Ti-B system. This increases the amount of acicular ferrite and improves the low-temperature toughness of the weld metal. While the patent claims the wire is suitable for high heat input welding, the examples only list the mechanical properties of the weld joint at a heat input of 44 kJ / cm. In high heat input welding (50~125kJ / cm), which is also applicable to this invention, 0.06~0.12% C and 1.2~1.8% Mn elements are severely burned off and easily cause insufficient weld metal strength. Therefore, in high heat input welding, it is necessary to add an appropriate amount of Mo element with a relatively stable transition or increase the content of Mn element to compensate for the loss of weld metal strength after the beneficial alloying elements are burned off.

[0004] Chinese invention patent application CN201010263712.4 discloses a high-strength, high-toughness submerged arc welding wire. The wire material has a Mn / Si ratio of 2.5~3.0 and employs a Mn-Mo-Ni-Cr-Ti-VB alloy design, resulting in a comprehensive improvement in the steel's overall performance, including strength, toughness, corrosion resistance, and machinability. While the wire in this patent contains 1.3~1.8% Mn, during submerged arc welding, a significant portion of the Si element in the weld metal or weld bead is transferred through the flux, leading to a high Si content in the weld metal or weld bead. This significantly reduces the toughness of the weld bead during high-heat welding.

[0005] Chinese invention patent application CN201610684773.5 discloses a high-strength, high-toughness submerged arc welding wire with the following composition: C≤0.10%; Mn: 1.5~2.0%; Si: 0.20~0.40%; S≤0.010%; P≤0.025%; Cr≤0.50%; Ni≤0.70%; Mo: 0.25~0.3%; Cu≤0.25%; B≤0.004%; and an appropriate amount of trace element Al is added. This invention is suitable for welding Q690 grade steel and has high yield strength, tensile strength, and excellent low-temperature impact toughness. However, the composition of the welding wire in this patent includes B but not Ti. If the welding wire is used for high heat input submerged arc welding, the trace B element is easily burned off. Furthermore, the high Si content in the welding wire composition means that some Si will be transferred into the weld metal through the flux during the submerged arc welding process, which can easily lead to an excessively high Si content and thus affect the low-temperature impact toughness of the weld metal.

[0006] Chinese invention patent application CN201410728048.4 discloses a high-heat-input submerged arc welding wire suitable for welding heat inputs of 60~160kJ / cm. It adds 0.01~0.05% Ti to form TiN, which pins austenite grain boundaries and prevents 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, which are high-melting-point composite oxides of Si, Mn, Ti, Al, Ce, and Mg. However, in this invention, the welding wire suffers significant Ti burn-off during high-heat-input welding (greater than 50kJ / cm), and the amount of 0.01~0.05% titanium transitioning into the weld metal is relatively small. Furthermore, high-heat-input welding test plates were performed in the embodiments, resulting in large weld metal fusion and increased dilution of the effective components of the weld metal. Consequently, the weld center of the test plate in the embodiments exhibited low low-temperature toughness under impact at -40℃.

[0007] 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 welding wire in this patent exhibits a significant grain growth trend. Simply adding Ni to refine the ferrite grains is insufficient to improve toughness, and adding too much Ni would increase the cost of welding wire smelting. Similarly, this patent is applicable to welding heat inputs of 30~40 kJ / cm, which is somewhat different from high-heat-input welding.

[0008] Therefore, in order to improve the welding manufacturing efficiency of large steel structures such as bridges, it is an important way to develop domestically produced submerged arc welding wire suitable for Q420~Q460qEHW grade welding with a heat input of 50~100kJ / cm, while meeting the requirements of relevant standards and specifications for the mechanical properties of welded joints, in order to improve welding efficiency, reduce costs, improve the mechanical properties of welded joints, and replace imported products. Summary of the Invention

[0009] The problem to be solved by the present invention is to provide a 600MPa grade multi-wire submerged arc welding electrode and welding wire suitable for high heat input welding of 100kJ / cm. The applicable heat input range is 50~100kJ / cm. It is matched with Fe powder-MgO-SiO2-CaF2-Al2O3 system alkaline sintered flux, has high deposition efficiency, excellent low temperature toughness, and strong adaptability to welding heat input range. It is suitable for efficient welding and manufacturing of large steel structures in bridges, ships and buildings.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a 600MPa grade multi-wire submerged arc welding wire rod suitable for welding with a high heat input of 100kJ / cm. The chemical composition of the wire rod, by mass percentage, includes: C: 0.07~0.12, Si≤0.09, Mn: 2.0~2.25, P≤0.012, S≤0.005, Ni: 0.05~0.5, Cr: 0.10~0.25, Mo: 0.2~0.38, Ti: 0.14~0.24, V: 0.03~0.04, B: 0.0005~0.0030, Zr≤0.015, rare earth La≤0.020, with the balance being Fe and unavoidable impurities. The five harmful elements Pb+Sn+As+Sb+Bi in the wire rod are ≤0.010.

[0011] Furthermore, the strength factor θ of the wire rod conforms to 627.2 ≤ θ ≤ 773.4.

[0012] Where θ = 9.8 × (36.69 + 180.4W) C +5.84W Mn +12.6W Cr +2.482W Ni +7.29W Mo +1.36W Ti ), W C The content of C in wire rod, W Mn W represents the Mn content in the wire rod. Cr W represents the Cr content in the wire rod. Ni W represents the Ni content in the wire rod. Mo W represents the Mo content in wire rod. Ti This represents the Ti content in the wire rod.

[0013] Furthermore, the chemical composition of C, Mn, Cr, Ni, and Mo in the wire rod satisfies 590 ≤ Bs ≤ 630.

[0014] Where, Bs = 830 - 221.4W C -65.7W Mn -63W Cr -27.01W Ni -74.7W Mo W C The content of C in wire rod, W Mn W represents the Mn content in the wire rod. Cr W represents the Cr content in the wire rod. Ni W represents the Ni content in the wire rod. Mo This represents the Mo content in the wire rod.

[0015] Furthermore, the chemical composition of Ni and Mn in the wire rod satisfies: 15% ≤ β ≤ 29%, where β = W Ni / (W) Mn +W Ni )*100%, W Mn W represents the Mn content in the wire rod. Ni This represents the Ni content in the wire rod.

[0016] Furthermore, the chemical composition of Si, Mn, and Ti in the wire rod satisfies: 0.040 ≤ α ≤ 0.057, where α = W Si / 14+W Mn / 55+W Ti / 24, W Si W represents the Si content in the wire rod. Mn The content of Mn in wire rod, W Ti This represents the Ti content in the wire rod.

[0017] The present invention also provides a 600MPa grade multi-wire submerged arc welding wire suitable for welding with a high heat input of 100kJ / cm, which is produced by drawing the above-mentioned wire rod.

[0018] Furthermore, a copper plating layer is provided on the surface of the welding wire, and the thickness of the copper plating layer is 0.18~0.22 micrometers.

[0019] Furthermore, sintered flux with an alkalinity BⅡW higher than 1.8 and welding process with a heat input of ≤100kJ / cm are used. The impact performance of the weld metal at -40℃ is not less than 60J, the yield strength is not less than 460MPa, the tensile strength is greater than 600MPa, and the elongation A of the weld metal is ≥20%.

[0020] Furthermore, the weld metal deposited by the welding wire is mainly composed of a multiphase structure of acicular ferrite and granular bainite, with the acicular ferrite content being 62-73%.

[0021] The beneficial effects of this invention are:

[0022] (1) The welding wire of the present invention, through reasonable design of chemical composition, produces weld metal with excellent comprehensive performance under a heat input of 50~100kJ / cm, exhibiting high tensile strength and low-temperature impact toughness. The weld metal of the welding wire of the present invention has the following mechanical properties: yield strength Rp0.2 / MPa: 490~515MPa, tensile strength Rm / MPa: 610~640MPa, elongation A / %: 21.5~24.5%, impact absorption energy Akv-40℃ / J: 80~117J;

[0023] (2) The welding wire of the present invention is applicable to submerged arc welding, flux copper backing method and other high heat input multi-wire eutectic pool welding operations. The welding parameter range is wide, the welding process performance is stable under heat input of 50~100kJ / cm, the molten pool has good fluidity, the deposited metal is beautifully formed and has excellent crack resistance.

[0024] (3) The welding wire alloy system of the present invention is reasonably controlled, and its wire rod smelting, rolling and welding wire drawing processes are easy to implement, with stable quality, and are suitable for large-scale promotion and application.

[0025] The present invention will now be described in detail with reference to the accompanying drawings. Attached Figure Description

[0026] Figure 1 The metallographic structure diagram is shown in Example 1.

[0027] Figure 2 The metallographic structure diagram is shown in Example 5;

[0028] Figure 3 This is a metallographic diagram of Comparative Example 2;

[0029] Figure 4 This is the metallographic structure diagram of Comparative Example 4. Detailed Implementation

[0030] This invention provides a 600MPa grade multi-wire submerged arc welding electrode suitable for welding with a high heat input of 100kJ / cm. Its chemical composition, by mass percentage, includes: C: 0.07~0.12, Si≤0.09, Mn: 2.0~2.25, P≤0.012, S≤0.005, Ni: 0.05~0.5, Cr: 0.10~0.25, Mo: 0.2~0.38, Ti: 0.14~0.24, V: 0.03~0.04, B: 0.0005~0.0030, Zr≤0.015, rare earth La≤0.020, with the balance being Fe and unavoidable impurities.

[0031] The five harmful elements in the wire rod are Pb+Sn+As+Sb+Bi≤0.010, and the intensity factor θ conforms to 627.2≤θ≤773.4.

[0032] θ = 9.8 × (36.69 + 180.4W) C +5.84W Mn +12.6W Cr +2.482W Ni +7.29W Mo +1.36W Ti ).

[0033] The chemical composition of C, Mn, Cr, Ni, and Mo in the above-mentioned wire rods satisfies 590 ≤ Bs ≤ 630, where Bs = 830 - 221.4 W. C -65.7W Mn -63W Cr -27.01W Ni -74.7W Mo .

[0034] The chemical composition of Ni and Mn in the above wire rods satisfies: 15% ≤ β ≤ 29%, β = W Ni / (W) Mn +W Ni )*100%.

[0035] The chemical composition of Si, Mn, and Ti in the above wire rods satisfies: 0.040 ≤ α ≤ 0.057, α = W Si / 14+W Mn / 55+W Ti / twenty four.

[0036] Among them, W C The content of C in wire rod, W SiW represents the Si content in the wire rod. Mn W represents the Mn content in the wire rod. Cr W represents the Cr content in the wire rod. Ni W represents the Ni content in the wire rod. Mo W represents the Mo content in wire rod. Ti This represents the Ti content in the wire rod.

[0037] The functions and mechanisms of each component in wire rod are as follows:

[0038] C: Carbon increases the strength of weld metal, but also significantly reduces 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 0.07-0.12%, preferably 0.077-0.093%.

[0039] Silicon (Si) is an effective deoxidizing element in the welding process. When the silicon content in the weld metal is less than 0.1%, the deoxidation effect is poor, and porosity is prone to occur in the weld metal. When the silicon content in the weld metal is greater than 0.6%, the toughness of the weld metal is significantly reduced. For submerged arc welding, the silicon in the weld metal after welding will be transferred from the base metal and the submerged arc welding flux. Therefore, the silicon content in the welding wire composition is limited to ≤0.09%.

[0040] Manganese (Mn) is a crucial deoxidizing element, effectively reducing the oxygen content in weld metal. Mn also improves hardenability, refines the microstructure, and enhances weld metal strength through solid solution strengthening. When the Mn content is below 1.2%, the weld metal strength is insufficient and it is detrimental to preventing welding hot cracking; when the Mn content is above 1.9%, martensitic structures are easily formed, leading to a significant decrease in toughness. Considering the substantial loss of manganese during high-heat welding, the manganese content in this welding wire is controlled between 2.0% and 2.25%, preferably between 2.08% and 2.15%.

[0041] Ni: Nickel is an austenite-forming element that can improve the low-temperature toughness of weld metal. In order to ensure that the weld metal has a certain degree of ductility and toughness under high heat input welding conditions, 0.05~0.5% nickel (preferably 0.1~0.4%, more preferably 0.2~0.4%) is added to toughen the ferrite matrix, reduce its brittle transition temperature, and improve low-temperature toughness.

[0042] Cr: Chromium can significantly improve the strength, hardness and wear resistance of welds, but excessive Cr content will cause carbide segregation, which will lead to a decrease in the impact toughness of the weld metal. Therefore, the Cr content in this invention is controlled at 0.1~0.25%, preferably 0.17~0.22%.

[0043] Mo: Molybdenum is a carbide-forming element that significantly improves strength, but it also has a certain adverse effect on low-temperature toughness. Considering the overall influence of molybdenum on the properties of weld metal, the Mo content in the welding wire composition is limited to 0.2~0.38%, preferably 0.26~0.35%.

[0044] Ti: In this invention, Ti is added to the submerged arc welding wire. Its main function is that the dispersed oxides and nitrides it forms 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 at 0.14~0.24%, preferably 0.17~0.20%.

[0045] Vanadium (V) ensures the room temperature strength, high temperature strength, and high temperature creep performance of welds. However, excessive V reduces low temperature impact toughness and makes the slag removal process in submerged arc welding difficult, resulting in poor weldability. Therefore, the V content in this invention is controlled at 0.03~0.04%, preferably 0.034~0.038%.

[0046] Boron (B): A strong grain boundary segregating element, it preferentially occupies grain boundary sites, preventing the segregation of impurity elements. Simultaneously, B can lower interfacial energy, controlling the precipitation of proeutectoid ferrite. Furthermore, Ti and B have a protective relationship: the addition of Ti prevents B from combining with N, improving grain boundary segregation; B protects Ti from excessive oxidation. The appropriate addition of Ti and B improves weld toughening and lowers the ductile-brittle transition temperature of the weld metal. Considering that B will be lost to some extent during high-heat-input welding, the B content in this welding wire is controlled at 0.0005~0.0030%, preferably 0.0012~0.0024%.

[0047] Zr can form high-melting-point inclusions in welds, 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 to ≤0.015%.

[0048] La: The rare earth element lanthanum can refine grains, promote the formation of acicular ferrite, improve the size and morphological distribution of inclusions in weld metal, enhance the toughness of weld metal, improve the dehydrogenation and deoxidation capacity of weld metal, reduce the formation of porosity in weld metal during welding, and reduce crack susceptibility. In this invention, the La content is controlled at La≤0.02%.

[0049] Sulfur (S) and phosphorus (P): These elements negatively impact the toughness of weld metal. Excessive S content can easily lead to weld cracking, so their content should be minimized, especially phosphorus (P). This is because the use of flux during submerged arc welding increases the P content in the weld metal. The recommended S content is no more than 0.005%, and the P content is no more than 0.012%.

[0050] In actual production, the strengthening of metallic materials is often achieved by preventing the movement of dislocations within defective metal crystals to increase strength. Specific strengthening and toughening methods include solid solution strengthening, dislocation strengthening, precipitation and dispersion strengthening, and grain boundary strengthening. In weld metal, Mn, Si, Ni, and Mo, which induce solid solution strengthening, are present in high concentrations, while trace elements such as Ti and B can form carbides or nitrides in the weld, which can also play a certain role in precipitation strengthening by pinning dislocations. However, solid solution strengthening has a particularly significant impact on strength, due to the effects of atomic size, elastic modulus, and the ordering of the solid solution, leading to bulk strengthening. The contribution of alloying elements to strength when alloying ferrite can be expressed by the following formula: In the formula, K i C is the strengthening coefficient of element i (MPa / wt%). i Let be the weight percentage concentration of element i dissolved in ferrite. Assuming the additive effect of alloying elements is linear, the following formula can be derived:

[0051] σ b =9.8 × (36.69 + 220W) C +8.0W Mn +14W Cr +3.4W Ni +8.1W Mo +8W Ti )

[0052] Used to calculate the strength value caused by chemical composition.

[0053] Meanwhile, during the high-heat welding process, the content of various alloying elements transitioning into the weld metal also changes significantly, which is related to the oxidation loss of alloying elements during welding heat. According to welding metallurgical theory, at 1600℃, the order of oxygen affinity of each element from smallest to largest is: Cu, Ni, Co, Fe, W, Mo, Cr, Mn, V, Si, Ti, Zr, Al. Since Fe has the highest concentration in the welding zone, some Fe will inevitably be oxidized; Ni, being the element to the left of Fe, has a relatively low affinity for oxygen, so its oxidation loss is minimal. Although Mo is to the right of Fe, its affinity for oxygen is close to that of Fe, and its concentration in the molten droplets and weld pool is low, so its oxidation loss is less, and its transition coefficient is larger; although the concentrations of Mn, Si, and Ti are not high, their high affinity for oxygen leads to more severe oxidation loss. Furthermore, Ti, being highly reactive, will react with nitrogen in the arc atmosphere to form TiN, which will further reduce its alloy transition coefficient. Therefore, in high-heat-input welding, it is necessary to consider both the strengthening and toughening effects of alloying elements on the weld metal and the element loss caused by high-heat-input welding. Thus, by combining the transition allowance of each alloying element after high-heat-input welding with the strength increment caused by chemical composition, a new expression for the strengthening and toughening factor θ is obtained:

[0054] θ = 9.8 × (36.69 + 180.4W) C +5.84W Mn +12.6W Cr +2.482W Ni +7.29W Mo +1.36W Ti The intensity factor θ satisfies 627.2≤θ≤773.4.

[0055] The preparation of the welding wire of this invention is the same as that of the prior art. The alloy composition of the wire rod of this invention is smelted and cast into steel ingots, then forged, rolled into wire rods, drawn into welding wires of the corresponding size, and then copper-plated and polished, wherein the thickness of the copper plating layer is 0.18~0.22um, and finally coiled and packaged into finished products.

[0056] The welding wire of this invention, when used in conjunction with a matching Fe powder-MgO-SiO2-CaF2-Al2O3 alkaline sintering flux, can be used for high-efficiency welding of Q420~Q460qE grade steel plates under a welding heat input of 50~100kJ / cm. The weld metal deposited by the wire exhibits an impact resistance of not less than 60J at -40℃, a yield strength of not less than 460MPa, a tensile strength greater than 600MPa, and an elongation A of the weld metal ≥20%. The weld metal deposited by the wire is mainly composed of a multiphase structure of acicular ferrite and granular bainite, with the acicular ferrite content ranging from 62% to 73%.

[0057] This invention employs a Mn-Mo-Cr-Ni-Ti-B system with appropriate Zr addition and strict control over S and P content. Under a heat input of 50~100 kJ / cm, suitable weld metal strength is ensured, the austenite and ferrite microstructure is refined, and acicular ferrite nucleation is induced, increasing the number of acicular ferrite and improving the low-temperature impact toughness of the weld metal. The combination of C, Mn, Mo, and Cr has a deoxidizing effect, reducing the oxygen content in the weld metal, and generates dispersed strong carbides Cr23C6 and Cr7C3, improving the strength and hardness of the weld metal, while also enhancing its crack resistance and low-temperature impact toughness, and improving the fluidity of the weld pool. Furthermore, adding appropriate amounts of Mn and Mo to the weld can increase the content and refinement effect of ferrite (AF), respectively, which is beneficial to improving impact toughness. Through the mutual protection between Ti and B elements, Ti's promoting effect on inclusions increases the AF content in the weld. Similarly, B can reduce the amount of proeutectoid ferrite, mitigating the damage to toughness caused by coarse microstructures. Adding appropriate amounts of Ni can toughen the ferrite matrix, lower its brittle transition temperature, and improve the stability of the weld metal's low-temperature toughness. In addition, adding appropriate amounts of Zr effectively refines inclusions in the weld metal and promotes MnS spheroidization. Zr can also form composite inclusions with other elements, which is beneficial for AF formation in the weld metal, thus improving weld metal toughness. Besides the need to rationally control the chemical composition range of each element as mentioned above, the following innovative technical requirements must be set to accurately control the relative addition amounts of certain key elements.

[0058] (1) By adjusting the formula 590≤Bs≤630, Bs=830-221.4W C -65.7W Mn -63W Cr -27.01W Ni -74.7W Mo By controlling the proportions of five elements—C, Mn, Ni, Cr, and Mo—the bainitic transformation temperature of the weld metal under high heat input can be controlled. Acicular ferrite, a type of bainitic structure, is formed through a mixed phase transformation mechanism of shear and diffusion in a range slightly above the bainitic transformation temperature. High heat input welding, due to its high energy and slow cooling rate, results in a longer residence time at high temperatures. The higher bainitic transformation temperature range is conducive to the formation of acicular ferrite during high heat input welding. However, if Bs is too high, coarse granular bainitic structure is easily formed, while if Bs is too low, a large amount of pearlite and proeutectoid ferrite is easily formed, thus affecting the low-temperature impact toughness.

[0059] (2) By adjusting the formula 0.040≤α≤0.057, α=W Si / 14+W Mn / 55+W Ti / 24, controlling the addition of Si, Mn, and Ti can effectively reduce the O content in the weld, while simultaneously generating SiO2, MnO, and TiO2. These formations preferentially occur under high-temperature conditions with high heat input, and during cooling, they promote the precipitation of sulfides, carbides, and nitrides on their surfaces, forming effective composite inclusions of 2-3 μm. These inclusions have high melting points and good thermal stability, effectively inducing acicular ferrite nucleation and refining the austenite intragranular structure, thus giving the weld metal good low-temperature impact toughness. When α is too low, oxygen atoms in the weld will react with elements with relatively weak oxygen affinity such as Ca and Al to form more ineffective inclusions such as CaO and Al2O3, causing a deterioration in the weld metal properties. When α is too high, the number and size of inclusions will increase, which will disrupt the continuity of the matrix, causing stress concentration in surrounding local areas, making it easier for microcracks to form, grow, and propagate at the two-phase interface.

[0060] (3) By adjusting the formula 15%≤β≤29%, β=W Ni / (W) Mn +W Ni Adding 100% Ni and Mn elements, controlling the Ni / Mn ratio, increases hardenability, resulting in a rightward shift in the CCT curve, inhibiting the growth of proeutectoid ferrite, altering weld solidification dynamics, and promoting the formation of acicular ferrite. While Mn promotes acicular ferrite formation, it also increases the precipitation of brittle pearlite in the recrystallization zone. Furthermore, the distribution of pearlite exhibits a directional, elongated pattern across the reheat zone with increasing Mn content, hardening the microstructure and worsening weld joint toughness. Adding an appropriate amount of Ni allows the microstructure to generate more irregularly shaped quasi-polygonal ferrite, hindering pearlite growth along elongated grain boundaries and suppressing the formation of large-sized granular bainite. However, the Ni content should not be less than 15% of the total Ni and Mn content, as this would lead to an excess of Mn, increasing the tendency for segregation. If β exceeds 29%, although a large amount of acicular ferrite will be produced, it will exceed the martensite formation line (Ms line), leading to the formation of martensite or other low-temperature phase transformation products, reducing weld joint toughness.

[0061] (4) By adjusting the formula 627.2≤θ≤773.4, θ=9.8×(36.69+180.4W) C +5.84W Mn +12.6W Cr +2.482W Ni +7.29W Mo +1.36W TiThe content of solid solution strengthening elements Mn, Si, Ni and Mo and precipitation strengthening element Ti are controlled. While considering the influence of alloying elements on the toughening of weld metal, the element burn-off problem caused by high heat input welding is also considered. The transition allowance of each alloying element after burn-off by high heat input welding is combined with the strength increment caused by chemical composition, so that the tensile strength of the weld wire cladding metal is not less than 650MPa.

[0062] The technical solution of the present invention will be described and explained in detail below with reference to specific embodiments.

[0063] The welding wire composition ratios for the following embodiments and comparative examples are shown in Tables 1 and 3. Based on the precisely calculated welding wire composition ratios, raw materials with low P, S, gas, and inclusion content were selected. The amount of alloy added was calculated. Welding wire steel was smelted in a 75kg vacuum induction furnace. After charging, melting, and refining, the steel was cast into ingots after meeting the composition requirements. The ingots were forged into square billets, rolled into 8.5mm wire rods, and then subjected to one coarse drawing and two fine drawing processes to produce 5.0mm submerged arc welding solid core welding wires. The welding wire quality was stable. Further, chemical copper plating was used to coat the surface of the welding wire, with the copper plating thickness controlled between 0.18 and 0.22 μm. The specific embodiments and comparative examples of the welding wire of this invention, and their chemical composition ratios (mass percentages), are shown in Tables 1 and 3 below.

[0064] Table 1. Chemical composition ratio (mass percentage) of submerged arc welding wires in Examples 1-3 and Comparative Examples 1-3 of the present invention (balance: Fe)

[0065] .

[0066] The above six types of welding wire (Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3) were used to conduct single-wire welding metal deposition tests according to the welding process parameters in Table 2 below. The welding heat input was 50 kJ / cm, and the welding used Fe powder-MgO-SiO2-CaF2-Al2O3 alkaline sintering flux. The layer temperature was controlled to be no more than 160℃.

[0067] Table 2 Bevel Forms for Deposited Metal Tests

[0068] .

[0069] Table 3 Chemical composition ratio (mass percentage) of submerged arc welding wires in Examples 4-6 and Comparative Examples 4-6 of the present invention (balance: Fe)

[0070] .

[0071] The above six types of welding wire (Example 4, Example 5, Example 6, Comparative Example 4, Comparative Example 5, Comparative Example 6) were used to conduct double-wire fusion metal tests according to the bevel pattern shown in Table 4 below. The welding heat input was 100 kJ / cm, and the welding used Fe powder-MgO-SiO2-CaF2-Al2O3 alkaline sintering flux. The layer temperature was controlled to be no more than 160℃.

[0072] Table 4 Bevel Forms for Welded Metal Tests

[0073] .

[0074] Samples were taken from the welded fusion metal, ensuring that the entire parallel length consisted of fusion metal. The sample size and test method followed 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 followed GB / T 229. The tensile and impact test results of the fusion metal are shown in Table 5, with the values ​​in parentheses representing averages.

[0075] Table 5 Mechanical properties of weld metal from the examples and comparative welding wires

[0076] .

[0077] The test results of the above embodiments show that the submerged arc welding solid wire of the present invention achieves various specification requirements for the mechanical properties of the deposited metal within a heat input range of 50~100kJ / cm, that is, while obtaining good strength and plasticity, it also has excellent low-temperature impact toughness, and the impact absorption energy Akv of the weld metal at -40℃ is 80~117J. Figure 1 and 2 As shown, the microstructure of the weld metal deposited by the welding wire of the present invention mainly consists of fine acicular ferrite and granular bainite, and the microstructure is uniformly distributed. Therefore, even under a high heat input of 100 kJ / cm, excellent low-temperature impact toughness can still be obtained. Figure 3 and 4 As shown, the microstructure of the weld seam of the comparative welding wire is mainly composed of proeutectoid ferrite, granular bainite and a small amount of acicular ferrite, with some containing a small amount of pearlite. The microstructure is relatively coarse and unevenly distributed, resulting in low-temperature impact toughness.

[0078] Therefore, the wire rod and welding wire of the present invention can be applied to the production and efficient welding manufacturing of large welded structural components in industries such as bridges, ships and buildings.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A 600MPa grade multi-wire submerged arc welding electrode suitable for welding with a high heat input of 100kJ / cm, characterized in that, The chemical composition of the wire rod, by mass percentage, includes: C: 0.07~0.12, Si≤0.09, Mn: 2.0~2.25, P≤0.012, S≤0.005, Ni: 0.05~0.5, Cr: 0.10~0.25, Mo: 0.2~0.38, Ti: 0.14~0.24, V: 0.03~0.04, B: 0.0005~0.0030, Zr≤0.015, rare earth La≤0.020, with the balance being Fe and unavoidable impurities; The five harmful elements Pb+Sn+As+Sb+Bi≤0.010; The chemical composition of C, Mn, Cr, Ni, and Mo in the wire rod satisfies 590 ≤ Bs ≤ 630. Where, Bs = 830 - 221.4W C -65.7W Mn -63W Cr -27.01W Ni -74.7W Mo W C The content of C in wire rod, W Mn W represents the Mn content in the wire rod. Cr W represents the Cr content in the wire rod. Ni W represents the Ni content in the wire rod. Mo This represents the Mo content in the wire rod.

2. The 600MPa grade multi-wire submerged arc welding electrode suitable for welding with a high heat input of 100kJ / cm as described in claim 1, characterized in that, The strength factor θ of the wire rod conforms to 627.2≤θ≤773.

4. Where θ = 9.8 × (36.69 + 180.4W) C +5.84W Mn +12.6W Cr +2.482W Ni +7.29W Mo +1.36W Ti ), W C The content of C in wire rod, W Mn W represents the Mn content in the wire rod. Cr W represents the Cr content in the wire rod. Ni W represents the Ni content in the wire rod. Mo W represents the Mo content in wire rod. Ti This represents the Ti content in the wire rod.

3. The 600MPa grade multi-wire submerged arc welding electrode suitable for high heat input welding of 100kJ / cm as described in claim 1, characterized in that, The chemical composition of Ni and Mn in the wire rod meets the following requirements: 15% ≤ β ≤ 29%. Where β=W Ni / (W) Mn +W Ni )*100%, W Mn W represents the Mn content in the wire rod. Ni This represents the Ni content in the wire rod.

4. The 600MPa grade multi-wire submerged arc welding electrode suitable for high heat input welding of 100kJ / cm as described in claim 1, characterized in that, The chemical composition of Si, Mn, and Ti in the wire rod satisfies: 0.040 ≤ α ≤ 0.

057. Where α=W Si / 14+W Mn / 55+W Ti / 24, W Si W represents the Si content in the wire rod. Mn The content of Mn in wire rod, W Ti This represents the Ti content in the wire rod.

5. A 600MPa grade multi-wire submerged arc welding wire suitable for welding with a high heat input of 100kJ / cm, characterized in that, It is produced by drawing wire rod as described in any one of claims 1-4.

6. The 600MPa grade multi-wire submerged arc welding wire suitable for welding with a high heat input of 100kJ / cm as described in claim 5, characterized in that, A copper plating layer is provided on the surface of the welding wire, and the thickness of the copper plating layer is 0.18~0.22 micrometers.

7. The 600MPa grade multi-wire submerged arc welding wire suitable for welding with a high heat input of 100kJ / cm as described in claim 5, characterized in that, Using alkalinity B ⅡW The welding process requires a sintered flux of ≤1.8 and a heat input of ≤100kJ / cm. The weld metal has an impact performance of not less than 60J at -40℃, a yield strength of not less than 460MPa, a tensile strength of greater than 600MPa, and an elongation A of ≥20% for the weld metal.

8. The 600MPa grade multi-wire submerged arc welding wire suitable for welding with a high heat input of 100kJ / cm as described in claim 7, characterized in that, The weld metal deposited by the welding wire is mainly composed of a multiphase structure of acicular ferrite and granular bainite.

9. The 600MPa grade multi-wire submerged arc welding wire suitable for welding with a high heat input of 100kJ / cm as described in claim 8, characterized in that, The content of acicular ferrite is 62-73%.

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