Solid welding wire for 1000MPa high-strength steel, preparation method and welding method

Abstract

The present invention provides a solid welding wire for 1000MPa high-strength steel, a preparation method, and a welding method. The chemical composition of the welding wire, by weight percentage, includes: C: 0.05-0.12wt%, Mn: 1.80-2.10wt%, Si: 0.55-0.90wt%, P: ≤0.025wt%, S ≤0.025wt%, Cr: 1.05-1.40wt%, Ni: 2.80-3.10wt%, Mo: 0.50-0.85wt%, Ti: 0.030-0.085wt%, V: 0.020-0.060wt%, Cu: 0.20-0.30wt%, the mass ratio of Cr to Ti+V being ≥10, and the mass ratio of Ni to Cr+Mo being ≥1.5; the balance being Fe. The welding wire has good comprehensive mechanical properties and is suitable for welding 1000MPa-grade high-strength steel.

Description

Technical Field

[0001] The present invention belongs to the field of welding wire production, and in particular relates to a solid welding wire for 1000MPa high-strength steel, a preparation method and a welding method. Background Art

[0002] As domestic and international industries such as engineering machinery, coal mining machinery, offshore engineering equipment, and hydropower equipment pursue higher-quality, higher-strength, higher-toughness, larger-scale, and lighter-weight designs, metal materials are expanding from traditional carbon and low-alloy steels to high-strength steels. To meet evolving industry demands, 1000MPa high-strength steel and its associated welding consumables have been increasingly adopted in recent years. Certain high-performance welding consumables require strength levels ≥1050MPa and yield strengths ≥960MPa. Currently, competition in the industry is fierce. To reduce costs and improve production efficiency, gas-shielded solid welding wire, with its intelligent and automated advantages, is rapidly developing and expanding its use.

[0003] The high alloying element content of 1000MPa high-strength steel and its welding materials significantly impacts the production and weld bead formation of welding wire. This makes the production of most 1000MPa solid welding wire difficult and time-consuming. Compared to ordinary carbon steel solid welding wire, the molten iron is thicker, resulting in poor weld bead formation. Furthermore, the high strength and hardenability of the deposited metal result in low impact toughness and a high risk of weld cracking, particularly cold and delayed cracking. This situation limits the development of this steel and its supporting welding materials. Most existing welding wires of this grade fail to achieve both a tensile strength exceeding 1000MPa and a yield strength of 960MPa while also meeting an impact energy requirement of ≥47J at -40°C. Even if these properties are met, they lack the ability to ensure good weld bead formation and a preparation method suitable for the raw material characteristics. Therefore, comprehensive research on the product performance, production process, and welding method applications of solid welding wire for 1000MPa high-strength steel is crucial. Summary of the Invention

[0004] In view of this, the present invention aims to propose a solid welding wire, preparation method and welding method for 1000MPa high-strength steel. The solid welding wire has a deposited metal yield strength of ≥960MPa, an impact toughness of ≥47J at -40℃, and is welded to ensure stable mechanical properties, which can meet the welding of high-strength steel with a strength level of 1000MPa and above.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A solid welding wire for 1000MPa high-strength steel, wherein the chemical composition of the welding wire comprises, by weight percentage, C: 0.05-0.12wt%, Mn: 1.80-2.10wt%, Si: 0.55-0.90wt%, P: ≤0.025wt%, S≤0.025wt%, Cr: 1.05-1.40wt%, Ni: 2.80-3.10wt%, Mo: 0.50-0.85wt%, Ti: 0.030-0.085wt%, V: 0.020-0.060wt%, Cu: 0.20-0.30wt%, the mass ratio of Cr to Ti+V is controlled to be ≥10, and the mass ratio of Ni to Cr+Mo is controlled to be ≥1.5; the total amount of unavoidable impurity elements is ≤0.3wt%, and the balance is Fe.

[0007] Furthermore, the mass ratio of Cr to Ti+V is 10-13, and the mass ratio of Ni to Cr+Mo is 1.5-1.8.

[0008] Carbon improves the strength and hardness of weld metal because it forms cementite with iron and increases the hardenability of the weld metal, thereby increasing the strength and hardness of the metal while reducing its plastic toughness. Excessive carbon content increases the crack sensitivity of the weld metal, especially if the carbon is not fully dissolved or the cooling rate is too rapid during welding, which can easily cause hot cracking. Therefore, the carbon content in the weld must be strictly controlled. Therefore, the carbon content of the present invention is 0.05-0.12wt%.

[0009] Mn acts as a deoxidizer and desulfurizer in the weld, helping to remove sulfides from the weld metal, reducing the formation of low-melting-point compounds, thereby reducing the tendency of weld defects and improving the toughness of the welded joint. Mn also promotes the formation of acicular ferrite in the weld metal, a microstructure that improves the material's strength and toughness. However, excessive Mn content can increase the hardenability of the weld metal, reducing its plasticity and toughness while increasing its strength. Therefore, the Mn content in the present invention is 1.80-2.10 wt%.

[0010] The Si element is used as a deoxidizer to prevent the weld metal from directly combining with oxygen. In addition, the Si element can reduce the surface tension of molten iron, improve the fluidity of molten iron, and avoid the weld defects caused by the excessive shrinkage of molten iron. Suitably increasing the Si element can also improve the yield strength and tensile strength of the weld metal by improving the microstructure of the weld metal. Excessive Si element may cause welding defects, such as the formation of pores and cracks, promote the generation of brittle phase, thereby reduce the toughness of the weld joint, reduce the fluidity of molten iron, and cause the weld to be poorly formed. Therefore, the content of Si of the present invention is 0.55-0.90wt%.

[0011] Phosphorus (P) and sulfur (S) are harmful impurities in the deposited metal that have a significant negative impact on the properties of the weld metal. Phosphorus can significantly increase the cold brittleness of steel, significantly reduce the impact toughness of the weld metal, and increase the brittle transition temperature, making cold brittleness more likely to occur at low temperatures. Sulfur, present primarily in the form of FeS and MnS in the weld metal, increases the risk of cracking in the weld and also reduces the impact toughness of the weld metal. Therefore, in the present invention, the P and S contents are controlled to S ≤ 0.025 wt% and P ≤ 0.025 wt%.

[0012] Nickel increases the hardenability of the weld metal, thereby increasing the content of the hardened phase in the weld region, improving the hardness and strength of the weld. It also improves the plasticity and toughness of the weld by refining the grain size, lowering the ductile-brittle transition temperature and improving its impact toughness. Excessive nickel content can increase the hardenability of the weld metal, increase the content of martensite, reduce the impact toughness of the weld metal, and increase crack sensitivity. Therefore, the present invention controls the nickel content to 2.80-3.10 wt%.

[0013] The addition of Mo contributes to the formation of hardened structures such as bainite and martensite, effectively improving the strength and hardness of the weld metal. Furthermore, the addition of Mo promotes the formation of a fine-grained structure in the weld metal, thereby simultaneously improving the weld's tensile strength and low-temperature impact toughness, achieving an optimal balance of strength and toughness. However, a higher Mo content increases product cost and reduces the weld metal's toughness and plasticity. To ensure the weld metal's comprehensive mechanical properties and economic efficiency, the Mo content in this invention is controlled within a range of 0.50-0.85 wt%.

[0014] Cr has a strong affinity for carbon atoms, readily forming chromium carbide compounds. Chromium carbide is an interstitial compound that reduces the proportion of other, harder interstitial phases, thereby improving the plasticity and toughness of the weld metal. It effectively increases the stability of austenite, reduces the precipitation of supersaturated carbides, and increases the strength and hardness of the weld metal after welding, while simultaneously reducing plasticity and toughness. Therefore, the Cr content must be maintained within a certain range. In the present invention, the Cr content is controlled within the range of 1.05-1.40 wt%.

[0015] The addition of Cr and Mo increases the surface tension of molten iron, affecting weld formation and performance when added in sufficient amounts. Ni, however, has a lower surface tension in the molten state, reducing the surface tension of molten iron and improving weld formation. Therefore, the amount of Cr and Mo added must maintain a specific relative relationship with Ni. In the present invention, the mass ratio of Ni to Cr+Mo is controlled to be ≥ 1.5. Preferably, the mass ratio of Ni to Cr+Mo is 1.5-1.8.

[0016] Cu has excellent electrical conductivity, surpassing that of steel. Therefore, during welding, Cu improves the overall electrical conductivity of the welding wire, contributing to stable arc combustion and current transfer during welding. However, excessive Cu content can cause segregation, reducing the plasticity and toughness of the weld metal and increasing material costs. The present invention controls the Cu content to 0.20-0.30 wt%.

[0017] In order to obtain good comprehensive mechanical properties of the weld metal, the present invention adds strong carbide-forming elements Ti and V through microalloying the alloy system.

[0018] The addition of Ti can form a strong TiC phase in the weld metal, which can improve the hardness and strength of the metal. In addition, the TiN formed by the reaction of Ti and N can serve as a crystallization core, promote nucleation, refine the weld grains, thereby improving the toughness and plasticity of the weld, and reducing the harmful effects of dissolved N. Ti is also an effective deoxidizer, forming a stable compound with oxygen in the air, reducing pores and inclusions in the weld, and improving the purity and uniformity of the weld. However, the Ti element can increase the viscosity of molten iron, reduce the fluidity of molten iron, and increase the risk of welding defects. Therefore, the Ti content of the present invention is controlled at 0.030-0.085wt%.

[0019] V is a strong carbide-forming element that reacts with carbon to form VC particles, which can be effectively dispersed in the weld. These particles can improve the strength and toughness of the weld. V also improves the wettability of the weld metal and reduces the formation of pores, thereby improving the overall quality of the weld. However, excessive V content can lead to a sharp decrease in the toughness of the weld metal, affecting the overall mechanical properties of the weld. Therefore, the V content in the present invention is controlled to 0.020-0.060wt%.

[0020] Because Ti and V are strong carbide-forming elements with a greater affinity for carbon than Cr, when added, they react with carbon to form carbides, reducing the amount of chromium carbide and increasing the ratio of interstitial phases and interstitial compounds, resulting in a decrease in the plasticity and toughness of the weld metal. Reducing the Ti and V content reduces the carbide content, but also reduces the grain-refining effect. Therefore, the interactions between Cr, Ti, and V in the weld metal require an appropriate ratio of addition to achieve optimal results. In the present invention, the mass ratio of Cr to Ti+V is controlled to be ≥10. Preferably, the mass ratio of Cr to Ti+V is 10-13.

[0021] The present invention also provides a method for preparing a solid welding wire for 1000MPa high-strength steel, which comprises the following steps: using a wire rod containing the above-mentioned chemical composition in the above-mentioned weight percentage, and sequentially subjecting it to full annealing treatment, pre-drawing, spheroidizing annealing treatment, rough drawing, spheroidizing annealing treatment, fine drawing and copper plating treatment to produce a finished solid welding wire.

[0022] Furthermore, the diameter of the solid welding wire is 1.0-1.2 mm.

[0023] Furthermore, the conditions for full annealing are: temperature 870-890° C., time 10 h-11 h.

[0024] Furthermore, the conditions for the two spheroidizing annealings are: temperature 760-790° C., time 10 h-11 h.

[0025] The annealing time of the welding wire product prepared by the present invention must ensure that the heated workpiece is completely burned through and the microstructure transformation process is completed, so it is controlled within the range of 10-11 hours.

[0026] The wire rod used in the present invention not only has a high alloy content, but also exhibits a primary structure dominated by hard and brittle phases, and exhibits severe work hardening. This leads to a sharp decrease in the wire rod's drawability during continuous drawing. Without annealing or with insufficient annealing cycles, frequent wire breakage can occur during drawing, rendering production impossible. Therefore, annealing is required before pre-drawing to improve the wire rod's drawability. Secondary and tertiary annealing are also required after pre-drawing and rough drawing to improve the wire rod's deformed structure after drawing, enhance its cold workability, and prevent wire breakage during drawing, which can disrupt smooth production. Therefore, the present invention employs two different annealing processes, each for different production stages.

[0027] The principle is as follows: Wire rod arrives at the mill in a hot-rolled state, free of lattice deformation caused by cold working. Annealing aims to eliminate structures such as martensite and bainite, reducing hardness. Therefore, a full annealing process is used, which achieves a near-equilibrium structure. After drawing, the wire rod undergoes cold working deformation, resulting in lattice deformation. Annealing aims to improve machinability, thus requiring spheroidizing annealing.

[0028] The weld metal structure of high-strength steel welding wire is sensitive to the stability of the welding process, and a stable welding process is an important guarantee for the mechanical properties of the weld.

[0029] The present invention also provides a welding method for a solid welding wire for 1000MPa high-strength steel as described above, wherein the shielding gas is 80vol%Ar+20vol%CO2, the gas flow rate is 15~20L / min, the welding current is 240~300A, the arc voltage is 26~30V, the welding speed is 24~42cm / min, the interlayer temperature is 140℃-160℃, and the welding line energy is 11.2~18.9KJ / cm.

[0030] Furthermore, when the welding wire diameter is 1.0 mm: the shielding gas is 80 vol% Ar + 20 vol% CO2, the gas flow rate is 15~20 L / min, the welding current is 240~270 A, the arc voltage is 26~28 V, the welding speed is 24~33 cm / min, the interlayer temperature is 140℃-160℃, and the welding line energy is 11.3~18.9 KJ / cm.

[0031] Furthermore, when the welding wire diameter is 1.2mm: the shielding gas is 80vol%Ar+20vol%CO2, the gas flow rate is 15~20L / min, the welding current is 280~300A, the arc voltage is 28~30V, the welding speed is 30~42cm / min, the interlayer temperature is 140℃-160℃, and the welding line energy is 11.2~18.0KJ / cm.

[0032] Under this welding method, the welding process can be guaranteed to be in a stable jet state, without the disturbance of the molten pool by short circuit or droplet transition, thus achieving stable weld metal properties.

[0033] Compared with the prior art, the solid welding wire for 1000MPa high-strength steel of the present invention has the following advantages:

[0034] (1) The solid welding wire for 1000MPa high-strength steel of the present invention is suitable for welding high-strength steel above 1000MPa level. The weld metal has good strength-toughness matching in the welded state. The mechanical properties of the deposited metal can reach yield strength ≥960MPa, tensile strength ≥1050MPa, elongation A ≥12%, and impact energy can also reach -40℃ impact toughness ≥47J. In addition, the molten iron has good fluidity, the arc is stable, and the molding is beautiful.

[0035] (2) The method for preparing a solid welding wire for 1000 MPa high-strength steel according to the present invention designs the drawing and annealing process sequence and annealing process parameters according to the chemical composition characteristics of the wire rod, so that the wire rod can be smoothly made into a welding wire.

[0036] (3) The welding method of the solid welding wire for 1000MPa high-strength steel described in the present invention solves the welding process problems of this product caused by the high strength and other reasons. The use of this welding method can make the performance of the product of the present invention reach the best effect. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Example 1

[0040] A solid welding wire for 1000MPa high-strength steel, wherein the chemical composition of the welding wire comprises, by weight percentage, 0.068wt% of C, 1.84wt% of Mn, 0.57wt% of Si, 1.07wt% of Cr, 2.95wt% of Ni, 0.70wt% of Mo, 0.070wt% of Ti, 0.025wt% of V, 0.28wt% of Cu, 0.020wt% of P, and 0.015wt% of S. The mass ratio of Cr to Ti+V is 11.3, the mass ratio of Ni to Cr+Mo is 1.67, and the balance is Fe and unavoidable impurities.

[0041] The preparation method of the welding wire is: using a wire rod containing the above-mentioned percentage of chemical composition to perform full annealing treatment - pre-drawing - spheroidizing annealing treatment - rough drawing - spheroidizing annealing treatment - fine drawing - copper plating treatment to produce a 1.2 mm finished solid welding wire.

[0042] The full annealing process is 870℃×10h, and the spheroidizing annealing process is 790℃×10h.

[0043] The metal arc welding method is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material for edging 2mm thick.

[0044] The groove of the welding test plate is in a Y-shape, and the groove angle on one side is 10°.

[0045] The protective gas used in this embodiment is a mixed gas: 80 vol% Ar+20 vol% CO2, and the gas flow rate is 15-20 L / min.

[0046] In this embodiment, the welding current is 280-300 A, the arc voltage is 29 V, the welding speed is 32 cm / min, the interlayer temperature is 140° C.-160° C., and the welding line energy is 14.7 KJ / cm.

[0047] The weld metal after welding in this embodiment was tested, and the yield strength was 975 MPa, the tensile strength was 1066 MPa, the elongation A=15%, the impact energy value Akv=70~85J at -40°C, and the weld bead was well formed, which is comparable to the level of the existing G49A4UM21S6 (ER70S-6) product with relatively good process performance.

[0048] Example 2

[0049] A solid welding wire for 1000MPa high-strength steel comprises, by weight percentage, 0.097wt% of C, 1.85wt% of Mn, 0.60wt% of Si, 1.10wt% of Cr, 2.95wt% of Ni, 0.55wt% of Mo, 0.060wt% of Ti, 0.035wt% of V, 0.28wt% of Cu, 0.018wt% of P, and 0.020wt% of S. The mass ratio of Cr to Ti+V is 11.58, the mass ratio of Ni to Cr+Mo is 1.79, and the balance is Fe and unavoidable impurities.

[0050] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.2 mm is prepared.

[0051] The welding method of the welding wire is also the same as that of the first embodiment.

[0052] The weld metal of this embodiment was tested after welding, and the yield strength was 983 MPa, the tensile strength was 1099 MPa, the elongation A=13.5%, and the impact energy value Akv=68~82J at -40°C, indicating good welding processability.

[0053] Example 3

[0054] A solid welding wire for 1000MPa high-strength steel comprises, by weight percentage, 0.10wt% C, 2.05wt% Mn, 0.74wt% Si, 1.21wt% Cr, 3.05wt% Ni, 0.70wt% Mo, 0.080wt% Ti, 0.040wt% V, 0.25wt% Cu, 0.015wt% P, and 0.020wt% S. The mass ratio of Cr to Ti+V is 10.08, the mass ratio of Ni to Cr+Mo is 1.60, and the balance is Fe and unavoidable impurities.

[0055] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.0 mm is prepared.

[0056] The same metal arc welding method as in Example 1 was used, but the specific welding parameters were different, as follows:

[0057] The shielding gas is 80vol%Ar+20vol%CO2, the gas flow rate is 15~20L / min, the welding current is 240~270A, the arc voltage is 27V, the welding speed is 29cm / min, the interlayer temperature is 140℃-160℃, and the welding line energy is 14.2KJ / cm.

[0058] The weld metal of this embodiment was tested after welding, and the yield strength was 990 MPa, the tensile strength was 1090 MPa, the elongation A=13.5%, and the impact energy value Akv=60~78J at -40°C, indicating good welding processability.

[0059] Example 4

[0060] A solid welding wire for 1000MPa high-strength steel has the following chemical compositions, calculated by weight percentage: 0.106wt% of C, 1.95wt% of Mn, 0.75wt% of Si, 1.24wt% of Cr, 3.00wt% of Ni, 0.75wt% of Mo, 0.050wt% of Ti, 0.055wt% of V, 0.27wt% of Cu, 0.012wt% of P, and 0.014wt% of S. The mass ratio of Cr to Ti+V is 11.81, the mass ratio of Ni to Cr+Mo is 1.51, and the balance is Fe and unavoidable impurities.

[0061] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.2 mm is prepared.

[0062] The welding method of the welding wire is also the same as that of the first embodiment.

[0063] The weld metal of this embodiment was tested after welding, and the yield strength was 1001 MPa, the tensile strength was 1100 MPa, the elongation A=12.2%, and the impact energy value Akv=51~69J at -40°C, indicating good welding processability.

[0064] Example 5

[0065] A solid welding wire for 1000MPa high-strength steel comprises, by weight percentage, 0.098wt% of C, 2.00wt% of Mn, 0.75wt% of Si, 1.34wt% of Cr, 3.08wt% of Ni, 0.65wt% of Mo, 0.070wt% of Ti, 0.042wt% of V, 0.21wt% of Cu, 0.023wt% of P, and 0.015wt% of S. The mass ratio of Cr to Ti+V is 11.96, the mass ratio of Ni to Cr+Mo is 1.55, and the balance is Fe and unavoidable impurities.

[0066] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.0 mm is prepared.

[0067] The welding method of the welding wire is the same as that of Example 3.

[0068] The weld metal of this embodiment was tested after welding, and the yield strength was 996 MPa, the tensile strength was 1104 MPa, the elongation A=14.2%, and the impact energy value Akv=63~85J at -40°C, indicating good welding processability.

[0069] Comparative Example 1 The mass ratio of Cr to Ti+V is different

[0070] A solid welding wire for 1000MPa high-strength steel, wherein the chemical composition of the welding wire comprises, by weight percentage, 0.068wt% of C, 1.84wt% of Mn, 0.57wt% of Si, 1.07wt% of Cr, 2.95wt% of Ni, 0.70wt% of Mo, 0.080wt% of Ti, 0.040wt% of V, 0.28wt% of Cu, 0.020wt% of P, and 0.015wt% of S. The mass ratio of Cr to Ti+V is 8.92, the mass ratio of Ni to Cr+Mo is 1.67, and the balance is Fe and unavoidable impurities.

[0071] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.2 mm is prepared.

[0072] The welding method of the welding wire is also the same as that of the first embodiment.

[0073] The weld metal of this embodiment was tested after welding, and the yield strength was 1000 MPa, the tensile strength was 1105 MPa, the elongation A=10%, and the impact energy value Akv=45~60J at -40°C, indicating good welding processability.

[0074] Comparative Example 2: Different mass ratios of Cr and Ti+V

[0075] A solid welding wire for 1000MPa high-strength steel, wherein the chemical composition of the welding wire comprises, by weight percentage, 0.068wt% of C, 1.84wt% of Mn, 0.57wt% of Si, 1.07wt% of Cr, 2.95wt% of Ni, 0.70wt% of Mo, 0.050wt% of Ti, 0.020wt% of V, 0.28wt% of Cu, 0.020wt% of P, and 0.015wt% of S. The mass ratio of Cr to Ti+V is 15.29, the mass ratio of Ni to Cr+Mo is 1.67, and the balance is Fe and unavoidable impurities.

[0076] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.2 mm is prepared.

[0077] The welding method of the welding wire is also the same as that of the first embodiment.

[0078] The weld metal of this embodiment was tested after welding, and the yield strength was 971 MPa, the tensile strength was 1089 MPa, the elongation A=11.5%, and the impact energy value Akv=43~59J at -40°C, indicating good welding processability.

[0079] Comparative Example 3 Ni and Cr+Mo mass ratios are different

[0080] A solid welding wire for 1000MPa high-strength steel, wherein the chemical composition of the welding wire comprises, by weight percentage, 0.068wt% of C, 1.84wt% of Mn, 0.57wt% of Si, 1.07wt% of Cr, 2.80wt% of Ni, 0.85wt% of Mo, 0.070wt% of Ti, 0.025wt% of V, 0.28wt% of Cu, 0.020wt% of P, and 0.015wt% of S. The mass ratio of Cr to Ti+V is 11.3, the mass ratio of Ni to Cr+Mo is 1.46, and the balance is Fe and unavoidable impurities.

[0081] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.2 mm is prepared.

[0082] The welding method of the welding wire is also the same as that of the first embodiment.

[0083] The weld metal of this embodiment was tested after welding, and the yield strength was 990 MPa, the tensile strength was 1087 MPa, the elongation A=14%, and the impact energy value Akv=50~63J at -40°C. The molten iron had poor fluidity during welding and poor forming.

[0084] Comparative Example 4 Ni and Cr+Mo mass ratios are different

[0085] A solid welding wire for 1000MPa high-strength steel, wherein the chemical composition of the welding wire comprises, by weight percentage, 0.068wt% of C, 1.84wt% of Mn, 0.57wt% of Si, 1.07wt% of Cr, 3.10wt% of Ni, 0.50wt% of Mo, 0.070wt% of Ti, 0.025wt% of V, 0.28wt% of Cu, 0.020wt% of P, and 0.015wt% of S. The mass ratio of Cr to Ti+V is 11.3, the mass ratio of Ni to Cr+Mo is 1.97, and the balance is Fe and unavoidable impurities.

[0086] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.2 mm is prepared.

[0087] The welding method of the welding wire is also the same as that of the first embodiment.

[0088] The weld metal of this embodiment was tested after welding, and the yield strength was 998 MPa, the tensile strength was 1096 MPa, the elongation A=15.5%, and the impact energy value Akv=50~72J at -40°C. The molten iron was not well formed during welding.

[0089] Comparative Example 5 Cr content is different

[0090] A solid welding wire for 1000MPa high-strength steel, wherein the chemical composition of the welding wire comprises, by weight percentage, 0.068wt% of C, 1.84wt% of Mn, 0.57wt% of Si, 0.90wt% of Cr, 2.95wt% of Ni, 0.70wt% of Mo, 0.060wt% of Ti, 0.020wt% of V, 0.28wt% of Cu, 0.020wt% of P, and 0.015wt% of S. The mass ratio of Cr to Ti+V is 11.25, the mass ratio of Ni to Cr+Mo is 1.67, and the balance is Fe and unavoidable impurities.

[0091] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.2 mm is prepared.

[0092] The welding method of the welding wire is also the same as that of the first embodiment.

[0093] The weld metal of this embodiment was tested after welding, and the yield strength was 938 MPa, the tensile strength was 1044 MPa, the elongation A=15.5%, and the impact energy value Akv=62~81J at -40°C, indicating good welding processability.

[0094] Comparative Example 6 Different Cr contents

[0095] A solid welding wire for 1000MPa high-strength steel, wherein the chemical composition of the welding wire comprises, by weight percentage, 0.068wt% of C, 1.84wt% of Mn, 0.57wt% of Si, 1.60wt% of Cr, 2.95wt% of Ni, 0.70wt% of Mo, 0.082wt% of Ti, 0.060wt% of V, 0.28wt% of Cu, 0.020wt% of P, and 0.015wt% of S. The mass ratio of Cr to Ti+V is 11.27, the mass ratio of Ni to Cr+Mo is 1.67, and the balance is Fe and unavoidable impurities.

[0096] The preparation method of the welding wire is the same as that in Example 1, and a finished solid welding wire of 1.2 mm is prepared.

[0097] The welding method of the welding wire is also the same as that of the first embodiment.

[0098] The weld metal of this embodiment was tested after welding, and the yield strength was 1020 MPa, the tensile strength was 1125 MPa, the elongation A=7%, and the impact energy value Akv=20~38J at -40°C, indicating good welding processability.

[0099] Comparative Example 7 Different preparation methods

[0100] The chemical composition of the welding wire is the same as that of Example 1.

[0101] The welding wire preparation method described above utilizes only full annealing. Specifically, using wire rod containing the aforementioned chemical composition percentages, the process involves full annealing, pre-drawing, full annealing, rough drawing, full annealing, fine drawing, and copper plating. However, the wire rod frequently breaks during the rough drawing process, disrupting normal production. This is due to the high alloy content in the wire rod, which increases the tendency for compositional segregation after pre-drawing, resulting in the formation of a hardened structure in some areas of the wire rod.

[0102] Comparative Example 8 Different preparation methods

[0103] The chemical composition of the welding wire is the same as that of Example 1.

[0104] The welding wire preparation method described above utilizes only spheroidizing annealing. Specifically, using wire rod containing the aforementioned chemical composition percentages, the process involves spheroidizing annealing, pre-drawing, spheroidizing annealing, rough drawing, spheroidizing annealing, fine drawing, and copper plating. However, the wire rod frequently breaks during the pre-drawing process, disrupting normal production. This is due to the high alloy content and good hardenability of the wire rod, resulting in a hardened, martensite-dominated microstructure upon arrival. Therefore, after spheroidizing annealing, the wire rod cannot achieve an equilibrium microstructure suitable for drawing.

[0105] Comparative Example 9 Different preparation methods

[0106] The chemical composition of the welding wire is the same as that of Example 1.

[0107] The welding wire preparation method employed a different annealing sequence. Specifically, using wire rod containing the aforementioned chemical composition percentages, the process was designed as follows: spheroidizing annealing - pre-drawing - full annealing - rough drawing - full annealing - fine drawing - copper plating. However, the same problem as in Comparative Example 8 occurred: frequent wire breakage during the pre-drawing process prevented normal production. This was also due to the inability to achieve a balanced microstructure conducive to drawing after spheroidizing annealing.

[0108] Table 1 Performance comparison of each embodiment and each comparative example

[0109]

[0110] Comparing the Examples and Comparative Examples 1-2 reveals that while the weight percentages of the various chemical components fall within the required range, the mass ratio of Cr to Ti+V does not meet the requirements. Specifically, the mass ratio of Cr to Ti+V in Comparative Example 1 is less than 10, while that in Comparative Example 2 is greater than 13. This results in a significant decrease in the elongation and -40°C impact energy of the welding wire. Because Ti and V are strong carbide-forming elements with a greater affinity for carbon than Cr, when added, they react with carbon to form carbides, reducing the amount of chromium carbide and increasing the ratio of interstitial phases to interstitial compounds, resulting in a decrease in the plasticity and toughness of the weld metal. Reducing the Ti and V content reduces the carbide content, but also reduces the grain-refining effect. Therefore, the three elements Cr, Ti, and V in the weld metal interact with each other, and their addition ratios must be appropriate to achieve optimal results.

[0111] Comparing the Examples and Comparative Examples 3-4 reveals that while the weight percentages of the various chemical components are within the required range, the mass ratio of Ni to Cr+Mo does not meet the requirements. Specifically, the mass ratio of Ni to Cr+Mo in Comparative Example 3 is less than 1.5, and the mass ratio of Ni to Cr+Mo in Comparative Example 4 is greater than 1.8, resulting in poor molten iron fluidity and weld formation. This is because the addition of Cr and Mo increases the surface tension of the molten iron, which, when added in sufficient amounts, affects weld formation and performance. Ni, with its lower surface tension in the molten state, reduces the surface tension of the molten iron and improves weld formation. Therefore, the amounts of Cr and Mo added must maintain a certain relative relationship with Ni to achieve optimal results.

[0112] Comparing Comparative Examples 5 and 6 reveals that while the mass ratios of Cr to Ti+V and Ni to Cr+Mo meet the requirements, excessively low or high Cr content is detrimental to improving welding wire performance. This is because high-strength welding wires with a high concentration of alloying elements have poor plasticity and toughness due to their high permeability and high content of hardened phases. The addition of Cr increases carbide precipitation while improving permeability, resulting in grain refinement and improved plasticity and toughness. However, achieving optimal results requires that the Cr content, the mass ratio of Cr to Ti+V, and the mass ratio of Ni to Cr+Mo all meet the required proportional relationships.

[0113] Comparative Examples 1-6 show that welding wires with superior performance can only be produced when the weight percentages of the chemical components are within the required range and the mass ratios of Cr to Ti+V and Ni to Cr+Mo also meet the requirements.

[0114] By comparing Comparative Examples 7-9, it can be found that for the wire rod with high alloy content used in the present invention, changes in the annealing process, such as adopting a single annealing method or changing the annealing sequence, cannot produce welding wire normally.

[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A solid welding wire for 1000MPa high-strength steel, characterized by: The chemical composition of the welding wire includes, by weight percentage, C: 0.05-0.12wt%, Mn: 1.80-2.10wt%, Si: 0.55-0.90wt%, P: ≤0.025wt%, S≤0.025wt%, Cr: 1.05-1.40wt%, Ni: 2.80-3.10wt%, Mo: 0.50-0.85wt%, Ti: 0.030-0.085wt%, V: 0.020-0.060wt%, Cu: 0.20-0.30wt%, the mass ratio of Cr to Ti+V is 10-13, and the mass ratio of Ni to Cr+Mo is 1.5-1.8; the total amount of unavoidable impurity elements is ≤0.3wt%, and the balance is Fe.

2. A method for preparing a solid welding wire for 1000MPa high-strength steel, characterized by: The method comprises the following steps: using a wire rod and sequentially subjecting it to full annealing, pre-drawing, spheroidizing annealing, rough drawing, spheroidizing annealing, fine drawing and copper plating to produce the solid welding wire as claimed in claim 1.

3. The method for preparing a solid welding wire for 1000 MPa high-strength steel according to claim 2, characterized in that: The diameter of solid welding wire is 1.0-1.2mm.

4. The method for preparing a solid welding wire for 1000 MPa high-strength steel according to claim 2, wherein: The conditions for full annealing are: temperature 870-890°C, time 10h-11h.

5. The method for preparing a solid welding wire for 1000 MPa high-strength steel according to claim 2, wherein: The conditions for the two spheroidizing annealings are: temperature 760-790°C, time 10h-11h.

6. A method for welding a solid welding wire for 1000 MPa high-strength steel according to claim 1, characterized in that: The shielding gas is 80vol%Ar+20vol%CO2, the gas flow rate is 15~20L / min, the welding current is 240~300A, the arc voltage is 26~30V, the welding speed is 24~42cm / min, the interlayer temperature is 140℃-160℃, and the welding line energy is 11.2~18.9KJ / cm.

7. The welding method of a solid welding wire for 1000 MPa high-strength steel according to claim 6, characterized in that: When the welding wire diameter is 1.0mm: the shielding gas is 80vol%Ar+20vol%CO2, the gas flow rate is 15~20L / min, the welding current is 240~270A, the arc voltage is 26~28V, the welding speed is 24~33cm / min, the interlayer temperature is 140℃-160℃, and the welding line energy is 11.3~18.9KJ / cm.

8. The welding method for a solid welding wire for 1000 MPa high-strength steel according to claim 6, characterized in that: When the welding wire diameter is 1.2mm: the shielding gas is 80vol%Ar+20vol%CO2, the gas flow rate is 15~20L / min, the welding current is 280~300A, the arc voltage is 28~30V, the welding speed is 30~42cm / min, the interlayer temperature is 140℃-160℃, and the welding line energy is 11.2~18.0KJ / cm.

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