1300mpa grade super-high-strength and high-toughness gas shielded welding wire, its preparation method and matching welding process

Abstract

The application relates to the technical field of super-high-strength and high-toughness gas shielded welding wires and matching welding methods, in particular to a 1300MPa-grade super-high-strength and high-toughness gas shielded welding wire for engineering machinery and a preparation method and a matching welding process thereof, the chemical components of the welding wire are as follows (wt.%): C: 0.10-0.17%, Ni: 5.00-7.80%, Mo: 1.08-1.50%, Mn: 0.90-1.50%, Si: 0.30-0.80%, V: 0.27-0.55%, Cu: 0.43-0.72%, W: 1.60-2.80%, P<=0.01wt.%, S<=0.01wt.% and the balance is iron and inevitable impurities. The application also comprises a preparation method of a 1300MPa super-high-strength steel special welding wire and a welding method thereof. The deposited metal is prepared by adopting a V-shaped groove and a multi-layer and multi-pass welding process. The super-high-strength and low-temperature high-toughness gas shielded welding wire and the matching welding process have the advantages of excellent appearance quality of the deposited metal, less welding spatter, high arc stability, excellent process performance and mechanical performance and the like. The super-high-strength and low-temperature high-toughness gas shielded welding wire developed by the application and the matching welding method thereof can obtain the deposited metal with required performance.

Description

Technical Field

[0001] This invention relates to the technical field of ultra-high strength and high toughness gas shielded welding wire and its matching welding method, specifically to a 1300MPa grade ultra-high strength and high toughness gas shielded welding wire for engineering machinery, its preparation method and matching welding process. This welding wire and its matching welding method are applied to the welding of 1300MPa grade ultra-high strength steel structural components. Background Technology

[0002] In recent years, with the rapid development of construction machinery towards larger size, lighter weight, and higher reliability, higher requirements have been placed on the load-bearing capacity and weight reduction efficiency of structural materials. High-strength steel, as the core material for critical load-bearing components, has seen continuous breakthroughs in its strength levels. Currently, 1100MPa grade high-strength steel has been gradually applied in key components such as crane booms, concrete pump truck booms, excavator sticks, and mining truck frames, significantly reducing structural weight while improving overall machine performance. To further meet performance requirements under extreme working conditions, 1300MPa grade ultra-high-strength steel has become an important development direction in the construction machinery field.

[0003] Ultra-high strength steel of 1300MPa grade for construction machinery is typically produced using purification smelting technology, combined with microalloying design and controlled rolling and cooling processes, to achieve excellent strength reserves and a reasonable microstructure. While ensuring ultra-high strength, this type of steel must also possess good low-temperature toughness to ensure the safety of construction machinery under low-temperature, heavy-load impact, and complex stress conditions.

[0004] Welding, as an indispensable key process in engineering machinery manufacturing, directly determines the load-bearing capacity, fatigue life, and safety reliability of the overall structure through the performance of the welded joints. For 1300MPa grade ultra-high strength high-strength steel, the welded joints not only need to achieve strength matching with the base material but also need to possess similar low-temperature toughness to prevent the joint from becoming a weak point in the overall structure. However, due to the high carbon equivalent and significant hardening tendency of this grade of steel, cold cracking is prone to occur during welding, placing extremely high demands on welding materials and processes. In the field of engineering machinery, gas shielded welding has become a commonly used welding method due to its significant advantages such as high welding efficiency, strong process adaptability, and ease of automation. The performance of the matching gas shielded welding wire directly determines the welding quality. Currently, mature high-strength gas shielded welding wires both domestically and internationally are mainly for 800~1100MPa grade steels. There is a lack of mature dedicated welding wire products for steels above 1100MPa, let alone meeting the welding requirements of 1300MPa grade high-strength steel. Specifically, existing welding wires have a significant strength mismatch with 1300MPa grade base materials and exhibit low low-temperature toughness, making it difficult to simultaneously achieve a balance between high strength and high toughness. This results in the welded joint becoming a performance bottleneck in the overall structure, severely restricting the industrial application of 1300MPa grade high-strength steel in the field of engineering machinery. Therefore, developing a dedicated gas-shielded welding wire suitable for 1300MPa grade high-strength steel used in engineering machinery, along with its matching welding method, to achieve similar strength and low-temperature toughness between the deposited metal and the base material, has significant engineering value and an urgent market demand. Summary of the Invention

[0005] To address the aforementioned deficiencies in existing technologies, this invention provides a 1300MPa-grade ultra-high strength and high toughness gas-shielded welding wire, its preparation method, and a matching welding process. At the wire composition design level, a multi-element microalloying strategy and strict purity control are employed to precisely regulate the solid-state phase transformation behavior of the deposited metal. At the process implementation level, scientific welding parameter guidance is provided to ensure the stable reproduction of the mechanical properties of the deposited metal. This invention successfully solves the bottleneck of the lack of dedicated welding wire and matching welding methods for 1300MPa-grade ultra-high strength steel, providing key technical support for its engineering application in welded structures within the field of engineering machinery.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-strength, low-temperature, high-toughness gas-shielded welding wire, with the following chemical composition by weight percentage: C: 0.10-0.17%, Ni: 5.00-7.80%, Mo: 1.08-1.50%, Mn: 0.90-1.50%, Si: 0.30-0.80%, V: 0.27-0.55%, Cu: 0.43-0.72%, W: 1.60-2.80%, P≤0.01wt.%, S≤0.01wt.%, with the balance being iron and unavoidable impurities.

[0007] Furthermore, the preferred chemical composition of the welding wire is as follows: C: 0.11-0.15%, Ni: 5.20-7.60%, Mo: 1.10-1.30%, Mn: 1.00-1.20%, Si: 0.35-0.60%, V: 0.29-0.50%, Cu: 0.45-0.63%, W: 1.80-2.50%, P≤0.01wt.%, S≤0.01wt.%, with the balance being iron and unavoidable impurities.

[0008] A method for preparing an ultra-high strength, low temperature and high toughness gas shielded welding wire includes the following steps: (1) taking hot-rolled wire rod and annealing it; (2) pre-treating the surface and shape of the wire rod after annealing; (3) multi-pass drawing and intermediate annealing; (4) copper plating and layer winding.

[0009] Further, in step (1), the hot-rolled wire rod preparation process is as follows: first, a vacuum induction furnace is used for smelting or an electric furnace primary smelting combined with ladle refining is selected to obtain an ingot. The ingot is forged to obtain a forging billet. The forging billet is held at 1100-1150℃ for 1-3 hours and then hot-rolled. The diameter of the hot-rolled wire rod is 5.5-8.5mm.

[0010] Further, in step (2), the pretreatment specifically involves: removing the surface oxide scale from the wire rod and performing preliminary straightening; then using a belt sander to grind and polish the surface of the wire rod; the diameter of the pretreated wire rod is 5.4-8.48 mm.

[0011] Further, in step (3), the number of drawing passes in the multi-pass drawing is 8-15; the single-pass compression rate is 5-21%; an intermediate annealing treatment is performed after every 2-5 drawing passes; the number of annealing treatments is 2-4; the annealing conditions are 700-950℃ for 2-8 hours, followed by furnace cooling to room temperature, and then sanding with a belt. In step (4), the copper plating process uses a mixed solution of sulfuric acid and copper sulfate, with concentrations of 40-65 g / L and 55-70 g / L respectively, and the copper plating layer thickness is 0.2-0.3 μm; the layer winding process winds the welding wire into coils weighing 5-20 kg each.

[0012] A welding method using ultra-high strength, low temperature, high toughness gas-shielded welding wire includes the following steps: (1) Remove rust and grind the base material bevel and backing plate to be welded, and use V-shaped bevel for the preparation of the weld metal; (2) Multi-layer, multi-pass welding is performed using the welding wire described in claim 1 or 2.

[0013] Further, in step (1), the V-shaped bevel is machined with a bevel angle of 20-25° on one side; the base material is 1300MPa grade high-strength steel with a thickness of 15-30mm, and the composition is C: 0.15-0.19%, Cr: 0.50-0.70%, Ni: 1.30-1.5%, Mo: 0.40-0.60%, Mn: 0.85-0.95%, Si: 0.20-0.30%, Al: 0.04-0.07%, P≤0.01wt.%, S≤0.01wt.%, with the balance being iron and unavoidable impurities; the backing plate has a thickness of 10-20mm and the same composition as the base material.

[0014] Further, the welding method described in step (2) is gas metal arc welding, and the welding parameters are as follows: the gap at the root of the base material is 10-15mm, the welding current is 140-155A, the voltage is 23-26V, the welding speed is 350-400mm / min; the shielding gas is a mixture of Ar and CO2, wherein the volume percentage of Ar is 85-95%, the gas flow rate is 20-25L / min; the preheating temperature is 110-130℃, and the interpass temperature is 120-140℃; after welding in step (2), deposited metal is obtained.

[0015] Furthermore, the diameter of the welding wire used is 0.9-1.2 mm, and the properties of the deposited metal obtained after welding with this wire are as follows: Tensile properties of deposited metal at room temperature: Yield strength Re / Rp 0.2 ≥1100MPa, tensile strength Rm≥1300MPa, elongation A≥14%; Low-temperature impact performance of deposited metal: KV2 (-40℃) ≥27J.

[0016] In this invention, carbon (C) is the core element ensuring the strength of the weld metal. It primarily enhances the dislocation resistance of the matrix through solid solution strengthening and regulates the phase transformation point to achieve the formation of a martensitic / bainitic multiphase structure. Appropriately increasing the C content can effectively promote the composite phase transformation of martensite and bainite, forming a multiphase structure with a good balance of strength and toughness, thereby significantly improving the strength level of the weld metal. However, if the C content exceeds a critical value, it will significantly increase the hardenability of the weld metal, causing the formation of hard and brittle high-carbon martensite during cooling. This not only severely impairs low-temperature impact toughness but also significantly increases the susceptibility to cold cracking and the risk of brittle fracture under service conditions. Conversely, if the C content is too low, the solid solution strengthening effect is insufficient, resulting in a low yield strength of the weld metal. This invention limits the C content to 0.10-0.17%.

[0017] In this invention, Ni is a key alloying element determining the synergistic match between strength and toughness of the weld metal, with its core mechanism manifested as a dual effect of toughening and microstructure refinement. On the one hand, as an austenite stabilizing element, Ni significantly enhances weld strength through solid solution strengthening and promoting the formation of fine bainite / martensite. On the other hand, Ni effectively reduces stacking fault energy and ductile-brittle transition temperature, inhibiting crack initiation and propagation, thereby endowing the weld metal with excellent low-temperature toughness. Furthermore, Ni ensures microstructure uniformity by suppressing coarse Widmanstätten structure. However, when the Ni content exceeds a critical threshold, it leads to the formation of coarse polymeric bainite, weakening grain boundary strengthening and offsetting toughness gains, resulting in a decrease in low-temperature impact energy. Simultaneously, to avoid the formation of weld cold cracks, a higher preheating temperature makes it difficult for the weld metal to form a harder microstructure at low temperatures, resulting in lower yield strength. This invention limits the Ni content to 5.00-7.80%.

[0018] In this invention, Mo is a key element for achieving secondary hardening and microstructure control. Appropriate addition of Mo can significantly shrink the austenite phase region, forming bainite or martensite structures during continuous rapid cooling. Simultaneously, under the reheat cycle of multi-pass welding, Mo, as a strong carbide-forming element, can induce the precipitation of dispersed nanoscale carbides, greatly enhancing the strength of the weld metal through a strong precipitation strengthening effect without significantly sacrificing low-temperature toughness. However, if the Mo content exceeds a critical value, its excessive hardenability can lead to the formation of coarse polymeric bainite. Furthermore, excessive solid solution strengthening causes lattice distortion and coarsening of the precipitated phase, weakening the dispersion strengthening effect and becoming a potential brittle crack initiation point, severely impairing the impact toughness of the weld. This invention limits the Mo content to 1.08-1.50%.

[0019] In this invention, manganese (Mn) is a key austenite stabilizing and microstructure regulating element, with its mechanism of action encompassing three dimensions: microstructure evolution, solid solution strengthening, and metallurgical purification. First, Mn effectively inhibits the formation of proeutectoid ferrite by expanding the austenite phase region and lowering the austenite-to-ferrite transformation initiation temperature, promoting the formation of a strong and tough bainitic / martensite multiphase microstructure in the weld metal and significantly improving strength. Second, Mn synergistically deoxidizes with Si, reducing oxide inclusions, and simultaneously purifies grain boundaries by combining with sulfur to form manganese sulfide, suppressing hot cracking and improving weld purity. Furthermore, Mn can synergistically enhance austenite stability with Ni. However, when the Mn content exceeds a suitable range, its excessive hardenability will induce the formation of coarse aggregated bainite, leading to microstructure coarsening and severely impairing low-temperature toughness. This invention limits the Mn content to 0.90-1.50%.

[0020] In this invention, Si is a key metallurgical purification and deoxidation element, playing a decisive role in controlling weld purity. Due to its stronger affinity for oxygen than Fe, Si preferentially reacts with oxygen in the molten pool to form oxides. These oxides easily float and are discharged, significantly reducing the total oxygen content and oxide inclusion level in the weld metal, laying the foundation for excellent low-temperature toughness. Simultaneously, Si assists in improving weld strength through solid solution strengthening and works synergistically with Mn to effectively suppress porosity. However, excessive Si, while strengthening through solid solution, drastically sacrifices the ductility and toughness of the weld metal; furthermore, excessive hardenability strongly promotes the formation of coarse polymeric bainite, leading to microstructure coarsening and reduced effective grain boundary area, severely impairing low-temperature impact toughness; moreover, high Si content also worsens the surface tension and fluidity of the liquid metal, significantly increasing crack susceptibility. This invention limits the Si content to 0.30-0.80%.

[0021] In this invention, vanadium (V) is a key element for controlling microalloying and precipitation strengthening. Leveraging its strong affinity for carbon (C) and nitrogen (N), V induces the precipitation of numerous fine, dispersed nanoscale V(C, N) particles during interlayer reheating cycles in multi-pass welding. These nanophases effectively hinder dislocation slip and grain boundary migration through a "pinning effect," resulting in significant precipitation strengthening and grain refinement, which is one of the core pathways to improving the strength of the weld metal. However, excessive V leads to coarsening of the V(C, N) precipitates. These coarse particles not only lose their dispersion strengthening ability but also act as stress concentration points, becoming preferential initiation sites for microcracks or propagation channels for brittle fracture. Simultaneously, excessive V atoms dissolved in the matrix also adversely affect low-temperature toughness. This invention limits the V content to 0.27-0.55%.

[0022] In this invention, Cu is a key precipitation strengthening and microstructure control microalloying element. Appropriate addition of Cu utilizes its limited solubility in α-Fe to precipitate fine, dispersed Cu-rich nanophases during reheating between multiple weld layers. This phase effectively hinders dislocation slip through a coherent strengthening effect, producing a significant precipitation strengthening effect, which is an important supplementary approach to improving the strength of the weld metal. Simultaneously, the co-precipitation of nanoscale V(C, N) and Cu-rich nanophases exhibits higher thermodynamic stability and strengthening effect than a single nanophase. However, excessive Cu significantly expands the low-melting-point eutectic region and forms a low-melting-point liquid film at grain boundaries during the final stage of solidification, severely weakening grain boundary bonding and easily inducing crystallization cracks under shrinkage stress. Furthermore, the coarsened Cu-rich phase and Cu atoms segregated at grain boundaries become nucleation sites for micropores, severely impairing the weld's plasticity and low-temperature toughness. This invention limits the Cu content to 0.43-0.72%.

[0023] In this invention, W is a key element controlling microalloying and precipitation strengthening. Due to the strong interaction between W and C atoms, highly thermally stable nanoscale M2C carbides can be generated during the reheating process of the welding thermal cycle. These hard particles can effectively "pin dislocations" and inhibit substructure recovery, thus contributing a significant increment in secondary hardening. However, excessive W content will induce the formation of coarse polymeric bainite, deteriorating low-temperature toughness; at the same time, the severe lattice distortion and carbide coarsening caused by excess W atoms can induce the formation of microcracks. This invention limits the W content to 1.60-2.80%.

[0024] In this invention, P and S are impurity elements. P atoms have a strong tendency to agglomerate at grain boundaries, significantly increasing the cold brittleness of the weld metal. S and Fe readily form low-melting-point sulfides (FeS), which form liquid films at grain boundaries during the final stage of solidification, easily inducing solidification cracks. Furthermore, S can induce the nucleation of non-metallic inclusions, worsening the ductility and toughness of the weld metal. In this invention, the P and S content is controlled to ≤0.01 wt.%.

[0025] The smelting process for this gas-shielded welding wire is dually feasible: it can be smelted in a vacuum induction furnace or a process combining electric furnace primary smelting with ladle refining. Regardless of the smelting method used, the final chemical composition of the welding wire must fully meet the requirements of all the aforementioned elements.

[0026] In the welding method described in this invention, gas metal arc welding (GMAW) is used to prepare the weld metal. This welding method combines high welding efficiency with excellent automation adaptability, ensuring high efficiency and stability in the welding process. The welding heat input and the degree of interpass reheating are the core variables determining the evolution of the weld microstructure, mainly controlled by the welding current, welding voltage, and welding speed. If the welding heat input is too high, the number of passes required for weld metal preparation decreases, the number of welding thermal cycles and reheating decreases, fewer nano-precipitates precipitate, and the yield strength of the weld metal is lower. If the welding heat input is too low, the weld metal cools too quickly, inducing the formation of coarse polymeric bainite, leading to deterioration of toughness. Furthermore, excessively high welding speeds can cause insufficient wetting and spreading of the liquid metal, resulting in metallurgical bonding defects; excessively slow speeds are equivalent to overheating, causing abnormal austenite grain growth and coarsening of precipitates, resulting in a decrease in both strength and toughness. Therefore, this invention controls the welding current at 140-155A and, through coordinated control of the welding power supply, automatically matches the arc voltage within the range of 23-26V, controlling the welding speed at 350-400mm / min. Preheating temperature and interpass temperature are key factors in regulating the welding thermal cycle, suppressing cold cracking, and optimizing the solid-state phase transformation process. If the temperature is below the required lower limit, the weld cooling rate will increase sharply, leading not only to hydrogen supersaturation and accumulation, significantly increasing cold cracking sensitivity, but also inducing the formation of martensite or polymeric bainite, thus deteriorating low-temperature impact toughness. Conversely, if the temperature is too high, it easily causes abnormal austenite grain growth and the formation of coarsening structures, resulting in a simultaneous decrease in strength and toughness. Therefore, this invention sets the preheating temperature to 110-130℃ and the interpass temperature to 120-140℃. In gas metal arc welding (GMAW), the oxygen potential level of the shielding gas directly determines the development direction of the welding metallurgical reaction. Using a mixed protective gas consisting primarily of argon and a suitable amount of carbon dioxide can improve the physical properties of the electric arc and the flow behavior of the molten pool, thereby optimizing the wettability and forming quality of the deposited metal. However, if the proportion of carbon dioxide is too high, it will disrupt the metallurgical balance and cause severe oxidation of the molten pool. This will not only significantly increase the tendency for spatter and undercut, but also lead to the formation of excessive deoxidation products (oxide inclusions) in the liquid metal. These inclusions remain in the deposited metal after solidification, becoming the source of crack initiation. Therefore, this invention selects a protective gas with a composition of 85-95% Ar + CO2 to strictly suppress excessive oxidation while ensuring the stability of the arc process, thus ensuring that the deposited metal possesses excellent comprehensive mechanical properties.

[0027] This welding wire is used for welding 1300MPa grade ultra-high strength steel structural components in the field of engineering machinery. The welding process of deposited metal is as follows: before welding, the base plate and both sides of the base material are derusted and ground. The deposited metal adopts a V-shaped bevel, and the gap at the root of the base material is 10-15mm. A Φ1.2mm coiled wire is used. After each weld is completed, the weld bead is ground clean with a grinding wheel. The welding process is carried out by gas metal arc welding. The welding parameters are: welding current is 140-155A, voltage is 23-26V, welding speed is 350-400mm / min, shielding gas is 95%Ar+5%CO2, gas flow rate is 20L / min, preheating temperature is 110-130℃, and interpass temperature is 120-140℃. The deposited metal is obtained after welding.

[0028] The present invention has the following advantages: This invention relates to the technical field of ultra-high strength and high toughness gas shielded welding wire and its matching welding method, specifically to a 1300MPa ultra-high strength, low temperature and high toughness gas shielded welding wire for engineering machinery and its matching welding method. This welding wire and its matching welding method are applied to the welding of 1300MPa grade ultra-high strength steel structural components.

[0029] 1. Experimental verification shows that the ultra-high strength and high toughness gas shielded welding wire and its matching welding method of the present invention are suitable for welding 1300MPa grade ultra-high strength steel structural parts in the field of engineering machinery.

[0030] 2. The preparation process of the 1300MPa grade low temperature high toughness gas shielded welding wire of the present invention has low cost, easy process control, no wire breakage during the drawing process, and excellent appearance quality of the finished welding wire.

[0031] 3. When welding with the low-temperature high-toughness gas shielded welding wire for 1300MPa grade ultra-high strength steel described in this invention, it exhibits excellent process performance, specifically reflected in less spatter and stable arc combustion during the welding process.

[0032] 4. The low-temperature high-toughness gas shielded welding wire for 1300MPa grade ultra-high strength steel and its matching welding method of the present invention can obtain weld metal with the required performance.

[0033] 5. The weld metal prepared using the low-temperature, high-toughness gas-shielded welding wire for 1300MPa grade ultra-high strength steel of this invention meets the following performance requirements: the tensile properties of the weld metal at room temperature are: yield strength Re / Rp 0.2 ≥1100MPa, tensile strength Rm≥1300MPa, elongation A≥14%; low-temperature impact performance of the welded metal: KV2 (-40℃)≥27J; the ultra-high strength in this invention refers to the yield strength Re / Rp of the welded metal at room temperature. 0.2≥1100MPa, tensile strength Rm≥1300MPa, low temperature high toughness means that the impact energy of the welded metal at -40℃ is ≥27J. Attached Figure Description

[0034] Figure 1 Here is a typical metallographic structure diagram of the weld metal in Example 1; Figure 2 This is a typical metallographic structure diagram of the weld metal in Example 2. Detailed Implementation

[0035] In this invention, the smelting of welding wire ingots can be carried out using either a vacuum induction furnace or a process route combining electric furnace primary smelting with ladle refining. This invention provides a method for preparing ultra-high strength and high toughness gas-shielded welding wire, specifically including the following steps: (1) annealing treatment of hot-rolled wire rod: annealing of wire rod with a diameter of 140 mm after holding at 1100℃ for 2 hours. (1) Hot rolling of mm round forging billet to obtain wire rod with a diameter of 5.5 mm. The hot-rolled wire rod with a diameter of 5.5 mm is placed at 900℃ for 6 hours for annealing treatment and then cooled to room temperature in the furnace; (2) Surface and shape pretreatment: The cooled wire rod is sequentially fed into the mechanical peeling device through the wire feeding frame to remove the surface oxide scale and perform preliminary straightening; then the wire rod surface is deeply polished by a belt sander to thoroughly remove residual oxide scale and attached debris. The diameter of the treated wire rod is 5.48 mm; (3) Multi-pass drawing and intermediate heat treatment: The polished wire rod is initially drawn to a diameter reduction of 3.21 mm. The initial diameter reduction drawing adopts a multi-stage drawing process and controls the die ratio. That is, the die hole diameters on the drawing path are configured as 5.0 mm, 4.5 mm, 4.05 mm and 3.21 mm respectively; then it is held at 900℃ for 6 hours for annealing treatment. Annealing and furnace cooling are performed. After cooling, the wire is sanded and the diameter is 3.15 mm. Then, the wire is drawn to 2.4 mm for the second time. The die ratio is controlled to be 3.0 mm and 2.4 mm. The annealing, cooling and sanding process is repeated. Finally, the wire is drawn to 1.2 mm in diameter. The die ratio is controlled to be 2.14 mm, 1.90 mm, 1.51 mm, 1.36 mm and 1.20 mm. (4) Copper plating and layer winding: The wire drawn to 1.20 mm is surface cleaned to remove residual drawing powder and lubricant impurities. Then, copper plating is performed in a mixed solution of sulfuric acid and copper sulfate. The sulfuric acid concentration is 60 g / L, the copper sulfate concentration is 60 g / L, and the copper plating layer thickness is 0.2 μm. The copper-plated welding wire is layer wound and packaged in a specification of 15 kg / coil to obtain the ultra-high strength and high toughness gas shielded welding wire. The only difference between the various embodiments and the comparative examples lies in the types and proportions of alloying elements and the selection of welding process parameters.

[0036] The base material in the following examples and comparative examples is 15mm thick 1300MPa grade high-strength steel with the following composition: C: 0.18%, Cr: 0.60%, Ni: 1.32%, Mo: 0.50%, Mn: 0.91%, Si: 0.22%, Al: 0.06%, P≤0.01wt.%, S≤0.01wt.%, with the balance being iron and unavoidable impurities.

[0037] Example 1: The welding wire has a diameter of 1.2 mm. The basic chemical composition of this gas-shielded welding wire is (by weight): C: 0.13%, Ni: 5.53%, Mo: 1.23%, Mn: 1.13%, Si: 0.39%, V: 0.31%, Cu: 0.50%, W: 1.91%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0038] This embodiment provides a welding method for preparing a 15mm thick weld metal using 1300MPa grade high-strength steel gas-shielded welding wire. The method includes the following steps: The base metal is beveled with a V-shaped bevel angle of 22.5° (single-sided), and the backing plate is 10mm thick. The bevel and backing plate are cleaned using a grinding wheel to remove iron oxide scale and iron filings. The root gap of the base metal is 12mm. The above welding wire is used for gas metal arc welding (Gas Metal Arc Welding) (Panasonic TA1400 welding machine). The shielding gas is 95%Ar + 5%CO2, the gas flow rate is 20L / min, the preheating temperature is 120℃, the interpass temperature is 125℃, the welding current is 140A, the voltage is 24V, and the welding speed is 380mm / min. After each pass, the weld bead spaces are cleaned with a grinding wheel to remove spatter and surface defects, ensuring no contamination between layers before proceeding to the next pass. The microstructure of the weld metal obtained after welding is as follows: Figure 1 As shown, the material mainly consists of small-sized polymeric bainite, approximately 10 μm in size. The tensile properties of two weld metal specimens were measured according to GB / T 2652-2022 standard. The yield strength Re / Rp of the weld metal at room temperature was also measured. 0.2 =1136-1143MPa, tensile strength Rm=1315-1332MPa, elongation of weld metal=16-17%; the impact performance of three weld metal samples was measured according to GB / T 2650-2022 standard, and the impact energy KV2 at -40℃ at half the thickness of the weld metal plate was 27-31J.

[0039] Example 2: The welding wire has a diameter of 1.2 mm. The basic chemical composition of this gas-shielded welding wire is (by weight): C: 0.13%, Ni: 5.53%, Mo: 1.23%, Mn: 1.13%, Si: 0.39%, V: 0.31%, Cu: 0.50%, W: 1.91%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0040] In this embodiment, the detailed welding process for preparing a 15mm thick weld metal using gas-shielded welding wire for 1300MPa grade high-strength steel is the same as in Embodiment 1, except that: Deposited metal: Preheating temperature is 110℃, and interpass temperature is 120℃; The microstructure of the deposited metal obtained after welding is as follows: Figure 2 As shown, the deposited metal mainly consists of polymeric bainite with a small size of 10 μm. The yield strength Re / Rp of the weld metal was measured. 0.2 =1140-1165MPa, tensile strength Rm=1327-1345MPa, elongation of weld metal=14-15%, impact energy at -40℃ at half the thickness of weld metal plate=27-30J.

[0041] Comparative Example 1: The welding wire has a diameter of 1.2 mm. The basic chemical composition of this gas-shielded welding wire is (by weight): C: 0.13%, Ni: 5.53%, Mo: 1.23%, Mn: 1.13%, Si: 0.39%, V: 0.31%, Cu: 0.50%, W: 1.91%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0042] In this comparative example, the detailed welding process for preparing a 15mm thick weld metal using gas-shielded welding wire for 1300MPa grade high-strength steel is the same as in Example 1, except that: Deposited metal: Welding current is 150A, welding voltage is 25V, welding speed is 350mm / min, preheating temperature is 140℃, and interpass temperature is 150℃; The yield strength Re / Rp of the weld metal was obtained by testing. 0.2 =1034-1054MPa, tensile strength Rm=1312-1318MPa, elongation of weld metal=15-16%, impact energy of weld metal at -40℃ KV2=30-36J.

[0043] Comparative Example 2: The welding wire has a diameter of 1.2 mm. The basic chemical composition of this gas-shielded welding wire is (by weight): C: 0.13%, Ni: 5.53%, Mo: 1.23%, Mn: 1.13%, Si: 0.39%, V: 0.31%, Cu: 0.50%, W: 1.91%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0044] In this comparative example, the detailed welding process for preparing a 15mm thick weld metal using gas-shielded welding wire for 1300MPa grade high-strength steel is the same as in Example 1, except that: Deposited metal: Welding current is 240A, welding voltage is 29V, welding speed is 300mm / min, preheating temperature is 160℃, and interpass temperature is 170℃; The yield strength Re / Rp of the weld metal was obtained by testing. 0.2 =878-907MPa, tensile strength Rm=1298-1302MPa, elongation of weld metal=14-15%, impact energy of weld metal at -40℃ KV2=24-29J.

[0045] Comparative Example 3: The welding wire has a diameter of 1.2 mm and its basic chemical composition (by weight) is as follows: C: 0.13%, Ni: 5.53%, Mo: 1.23%, Mn: 1.13%, Si: 0.39%, V: 0.31%, Cu: 0.52%, W: 0.96%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0046] In this comparative example, the detailed welding process for preparing 15mm thick weld metal using gas-shielded welding wire for 1300MPa grade high-strength steel is no different from that in Example 1. The yield strength Re / Rp of the weld metal was obtained by testing. 0.2 =1138-1142MPa, tensile strength Rm=1315-1320MPa, elongation of weld metal=15-17%, impact energy of weld metal at -40℃ KV2=15-28J.

[0047] Comparative Example 4: The welding wire has a diameter of 1.2 mm and its basic chemical composition (by weight) is as follows: C: 0.14%, Ni: 5.51%, Mo: 1.21%, Mn: 1.13%, Si: 0.41%, V: 0.31%, Cu: 0.52%, W: 0.005%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0048] In this comparative example, the detailed welding process for preparing a 15mm thick weld metal using gas-shielded welding wire for 1300MPa grade high-strength steel is the same as in Example 1, except that: Deposited metal: Welding current is 150A, welding voltage is 25V, welding speed is 300mm / min, preheating temperature is 160℃, and interpass temperature is 165℃; The yield strength Re / Rp of the weld metal was obtained by testing. 0.2 =964-966MPa, tensile strength Rm=1279-1289MPa, elongation of weld metal=13-15%, impact energy of weld metal at -40℃ KV2=28-31J.

[0049] Comparative Example 5: The welding wire has a diameter of 1.2 mm and its basic chemical composition (by weight) is as follows: C: 0.14%, Ni: 5.51%, Mo: 1.21%, Mn: 1.13%, Si: 0.41%, V: 0.31%, Cu: 0.52%, W: 0.005%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0050] In this comparative example, the detailed welding process for preparing a 15mm thick weld metal using gas-shielded welding wire for 1300MPa grade high-strength steel is the same as in Example 1, except that: Deposited metal: Welding current is 180A, welding voltage is 25V, welding speed is 300mm / min, preheating temperature is 155℃, and interpass temperature is 165℃; The yield strength Re / Rp of the weld metal was obtained by testing. 0.2 =1001-1030MPa, tensile strength Rm=1225-1239MPa, elongation of weld metal=14-15%, impact energy of weld metal at -40℃ KV2=27-39J.

[0051] Comparative Example 6: The welding wire has a diameter of 1.2 mm. The basic chemical composition of this gas-shielded welding wire is (by weight): C: 0.11%, Ni: 7.56%, Mo: 1.21%, Mn: 1.14%, Si: 0.40%, V: 0.31%, Cu: 0.50%, W: 0.005%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0052] In this comparative example, the detailed welding process for preparing a 15mm thick weld metal using gas-shielded welding wire for 1300MPa grade high-strength steel is the same as in Example 1, except that: Deposited metal: Welding current is 270A, welding voltage is 28V, welding speed is 300mm / min, preheating temperature is 150℃, and interpass temperature is 160℃; The yield strength Re / Rp of the weld metal was obtained by testing. 0.2 =922-930MPa, tensile strength Rm=1312-1321MPa, elongation of weld metal=13-14%, impact energy of weld metal at -40℃ KV2=33-43J.

[0053] Comparative Example 7: The welding wire has a diameter of 1.2 mm. The basic chemical composition of this gas-shielded welding wire is (by weight): C: 0.11%, Ni: 7.52%, Mo: 1.21%, Mn: 1.14%, Si: 0.40%, V: 0.31%, Cu: 0.50%, W: 0.005%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0054] In this comparative example, the detailed welding process for preparing a 15mm thick weld metal using gas-shielded welding wire for 1300MPa grade high-strength steel is the same as in Example 1, except that: Deposited metal: Welding current is 180A, welding voltage is 25V, welding speed is 350mm / min, preheating temperature is 150℃, and interpass temperature is 160℃; The yield strength Re / Rp of the weld metal was obtained by testing. 0.2 =912-927MPa, tensile strength Rm=1293-1296MPa, elongation of weld metal=15-16%, impact energy of weld metal at -40℃ KV2=41-45J.

[0055] Comparative Example 8: The welding wire has a diameter of 1.2 mm. The basic chemical composition of this gas-shielded welding wire is (by weight): C: 0.13%, Ni: 5.45%, Mo: 1.21%, Mn: 1.12%, Si: 0.41%, V: 0.31%, Cu: 0.009%, W: 0.005%, P: <0.005%, S: <0.002%, with the remainder being iron and unavoidable impurities.

[0056] In this comparative example, the detailed welding process for preparing a 15mm thick weld metal using gas-shielded welding wire for 1300MPa grade high-strength steel is the same as in Example 1, except that: Deposited metal: Welding current is 180A, welding voltage is 25V, welding speed is 300mm / min, preheating temperature is 135℃, and interpass temperature is 140℃; The yield strength Re / Rp of the weld metal was obtained by testing.0.2 =1060-1062MPa, tensile strength Rm=1267-1280MPa, elongation of weld metal=14-17%, impact energy of weld metal at -40℃ KV2=21-29J.

[0057] Table 1 summarizes the room temperature tensile properties and low temperature impact properties of the weld metals in the above embodiments and comparative examples.

[0058] Table 1. Test results of room temperature tensile properties and low temperature impact properties of the weld metal in the examples and comparative examples.

[0059] As can be seen from Examples 1-2 and Comparative Examples 1-8: The chemical composition of the gas-shielded welding wire designed according to this invention and its matching welding method, as shown in Examples 1-2, meet the performance design requirements of this invention. The tensile properties of the deposited metal at room temperature are: yield strength Re / Rp. 0.2 ≥1100MPa, tensile strength Rm≥1300MPa, elongation A≥14%; low temperature impact performance of the weld metal: KV2 (-40℃)≥27J.

[0060] In Comparative Example 1, the preheating temperature and interpass temperature used in preparing the deposited metal were not within the range of the technical solution of this invention, and the yield strength of the deposited metal did not meet the design requirements of this invention. In Comparative Example 2, the welding current, welding voltage, welding speed, preheating temperature, and interpass temperature used in preparing the deposited metal were not within the range of the technical solution of this invention, and the yield strength, tensile strength, and -40°C impact energy of the deposited metal did not meet the design requirements of this invention. In Comparative Example 3, the W content of the gas-shielded welding wire was not within the range of the technical solution of this invention, and the -40°C impact energy of the deposited metal did not meet the design requirements of this invention. In Comparative Example 4, the W content of the gas-shielded welding wire, the welding speed used in preparing the deposited metal, the preheating temperature, and the interpass temperature were not within the range of the technical solution of this invention, and the yield strength, tensile strength, and elongation of the deposited metal did not meet the design requirements of this invention. In Comparative Example 5, the W content of the gas-shielded welding wire, the welding current used in preparing the deposited metal, the welding speed, the preheating temperature, and the interpass temperature were not within the range of the technical solution of this invention, and the yield strength and tensile strength of the deposited metal did not meet the design requirements of this invention. In Comparative Example 6, the W content of the gas-shielded welding wire, the welding current, welding voltage, welding speed, preheating temperature, and interpass temperature used in the preparation of the deposited metal were not within the range of the technical solution of this invention, and the yield strength and elongation of the deposited metal did not meet the design requirements of this invention. In Comparative Example 7, the W content of the gas-shielded welding wire, the welding current, preheating temperature, and interpass temperature used in the preparation of the deposited metal were not within the range of the technical solution of this invention, and the yield strength and tensile strength of the deposited metal did not meet the design requirements of this invention. In Comparative Example 8, the Cu and W content of the gas-shielded welding wire, the welding current, welding speed, and preheating temperature used in the preparation of the deposited metal were not within the range of the technical solution of this invention, and the yield strength, tensile strength, and -40°C impact energy of the deposited metal did not meet the design requirements of this invention.

Claims

1. A high-strength, low-temperature, high-toughness gas-shielded welding wire, characterized in that: The chemical composition of this welding wire, by weight percentage, is as follows: C: 0.10-0.17%, Ni: 5.00-7.80%, Mo: 1.08-1.50%, Mn: 0.90-1.50%, Si: 0.30-0.80%, V: 0.27-0.55%, Cu: 0.43-0.72%, W: 1.60-2.80%, P≤0.01wt.%, S≤0.01wt.%, with the balance being iron and unavoidable impurities.

2. The ultra-high strength, low temperature high toughness gas shielded welding wire according to claim 1, characterized in that: The preferred chemical composition of this welding wire, by weight percentage, is as follows: C: 0.11-0.15%, Ni: 5.20-7.60%, Mo: 1.10-1.30%, Mn: 1.00-1.20%, Si: 0.35-0.60%, V: 0.29-0.50%, Cu: 0.45-0.63%, W: 1.80-2.50%, P≤0.01wt.%, S≤0.01wt.%, with the balance being iron and unavoidable impurities.

3. A method for preparing an ultra-high strength, low-temperature high-toughness gas-shielded welding wire as described in any one of claims 1-2, characterized in that: Includes the following steps: (1) Take hot-rolled wire rod and anneal it; (2) Surface and shape pretreatment of wire rod after annealing; (3) multi-pass drawing and intermediate annealing treatment; (4) copper plating and layer winding.

4. The method for preparing ultra-high strength, low temperature high toughness gas shielded welding wire according to claim 3, characterized in that: In step (1), the hot-rolled wire rod preparation process is as follows: first, a vacuum induction furnace is used for smelting or an electric furnace primary smelting combined with ladle refining is selected to obtain an ingot. The ingot is forged to obtain a forging billet. The forging billet is held at 1100-1150℃ for 1-3 hours and then hot-rolled. The diameter of the hot-rolled wire rod is 5.5-8.5mm.

5. The method for preparing ultra-high strength, low temperature high toughness gas shielded welding wire according to claim 3, characterized in that: In step (2), the pretreatment specifically involves: removing the surface oxide scale from the wire rod and performing preliminary straightening; then using a belt sander to grind and polish the surface of the wire rod; the diameter of the pretreated wire rod is 5.4-8.48 mm.

6. The method for preparing ultra-high strength, low temperature high toughness gas shielded welding wire according to claim 3, characterized in that: In step (3), the number of drawing passes in the multi-pass drawing is 8-15; the single-pass compression rate is 5-21%; an intermediate annealing treatment is performed after every 2-5 drawing passes; the number of annealing treatments is 2-4; the annealing conditions are 700-950℃ for 2-8 hours, followed by furnace cooling to room temperature, and then sanding with a belt. In step (4), the copper plating process uses a mixed solution of sulfuric acid and copper sulfate, with concentrations of 40-65 g / L and 55-70 g / L respectively, and the copper plating layer thickness is 0.2-0.3 μm; the layer winding process winds the welding wire into coils weighing 5-20 kg each.

7. A method for welding using the ultra-high strength, low temperature, high toughness gas-shielded welding wire as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Remove rust and grind the base material bevel and backing plate to be welded, and use V-shaped bevel for the preparation of the weld metal; (2) Multi-layer, multi-pass welding is performed using the welding wire described in claim 1 or 2.

8. The welding method according to claim 7, characterized in that: The V-shaped bevel mentioned in step (1) has a bevel angle of 20-25° on one side; the base material is 1300MPa grade high-strength steel with a thickness of 15-30mm, and the composition is C: 0.15-0.19%, Cr: 0.50-0.70%, Ni: 1.30-1.5%, Mo: 0.40-0.60%, Mn: 0.85-0.95%, Si: 0.20-0.30%, Al: 0.04-0.07%, P≤0.01wt.%, S≤0.01wt.%, with the balance being iron and unavoidable impurities; the backing plate has a thickness of 10-20mm and the same composition as the base material.

9. The welding method according to claim 7, characterized in that: The welding method described in step (2) is gas metal arc welding. The welding parameters are as follows: the gap at the root of the base material is 10-15mm, the welding current is 140-155A, the voltage is 23-26V, and the welding speed is 350-400mm / min. The shielding gas is a mixture of Ar and CO2, in which Ar accounts for 85-95% of the volume and the gas flow rate is 20-25L / min. The preheating temperature is 110-130℃ and the interpass temperature is 120-140℃. After welding in step (2), deposited metal is obtained.

10. A method for welding with ultra-high strength, low temperature high toughness gas shielded welding wire according to any one of claims 7-9, characterized in that: The welding wire has a diameter of 0.9-1.2 mm, and the properties of the deposited metal obtained after welding with this wire are as follows: Tensile properties of deposited metal at room temperature: Yield strength Re / Rp 0.2 ≥1100MPa, tensile strength Rm≥1300MPa, elongation A≥14%; Low-temperature impact performance of deposited metal: KV2 (-40℃) ≥27J.

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