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

Abstract

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

Description

Technical Field

[0001] The 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 foreign engineering machinery, coal mining machinery, marine equipment, hydropower equipment and other industries develop towards high quality, high strength, high toughness, large-scale and lightweight, metal materials have expanded from traditional carbon steel and low alloy steel to high-strength steel. In order to meet the needs of the ever-changing industry, 1000MPa high-strength steel and its supporting welding materials have been gradually promoted and applied in recent years. Some high-level welding materials require strength levels ≥1050MPa and yield strength ≥960MPa. At present, the industry is highly competitive. In order to reduce costs and improve production efficiency, gas-shielded solid welding wires with advantages such as intelligence and automation have developed rapidly, and the proportion of application has gradually expanded.

[0003] Due to the high content of alloy elements in 1000MPa high-strength steel and its welding materials, the production and manufacturing of welding wires and the formation of welds are seriously affected, resulting in the difficulty and long production cycle of most 1000MPa solid welding wires. Compared with ordinary carbon steel solid welding wires, the molten iron is viscous and the weld formation is not good. At the same time, the deposited metal has high strength and high hardenability, which makes its impact toughness low and the risk of welding cracks is high, especially cold cracks and delayed cracks. This situation limits the development of this type of steel and its supporting welding materials. Most of the existing welding wires of this level cannot meet the requirements of -40℃ impact energy ≥47J while having a tensile strength of more than 1000MPa and a yield strength of 960MPa. When the performance is met, it is impossible to guarantee good weld formation and a preparation method suitable for the characteristics of raw materials. Therefore, it is of great significance to conduct an integrated study on the product performance, production process and welding method application of solid welding wire for 1000MPa high-strength steel. 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°C, 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: A solid welding wire for 1000MPa high-strength steel, the chemical composition of the welding wire comprising, 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 sum of inevitable impurity elements is ≤0.3wt%, and the balance is Fe.

[0006] 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.

[0007] The C element can improve the strength and hardness of the weld metal, because carbon can form cementite with iron and improve the hardenability of the weld metal, thereby increasing the strength and hardness of the metal while reducing its plastic toughness. Too high a C content will increase the crack sensitivity of the weld metal, especially if the carbon is not fully dissolved or the cooling rate is too fast during the welding process, thermal cracks are easily generated. Therefore, the carbon content in the weld should be strictly controlled, so the C content of the present invention is 0.05-0.12wt%.

[0008] Mn is a deoxidizer and desulfurizer in the weld, which can help remove sulfides in the weld metal, reduce the formation of low melting point compounds, thereby reducing the tendency of welding defects and improving the toughness of the welded joint. The Mn element can also promote the formation of acicular ferrite in the weld metal, and this microstructure can improve the strength and toughness of the material. However, too high a Mn content will lead to an increase in the hardenability of the weld metal, while increasing the strength and reducing its plastic toughness, so the content of Mn in the present invention is 1.80-2.10wt%.

[0009] 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 weld defects caused by excessive shrinkage of molten iron. Appropriately 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 elements may cause welding defects, such as the formation of pores and cracks, promote the generation of brittle phases, thereby reducing the toughness of the weld joint, reducing the fluidity of molten iron, and causing poor weld formation. Therefore, the content of Si in the present invention is 0.55-0.90wt%.

[0010] P and S are harmful impurities in the deposited metal, which have a significant negative impact on the performance of the weld metal. Phosphorus can significantly increase the cold brittleness of steel, greatly reduce the impact toughness of the weld metal, and increase the brittle transition temperature, so that cold brittleness is prone to occur at low temperatures. Sulfur mainly exists in the form of FeS and MnS in the weld metal, which increases the crack risk of the weld. Sulfur can also reduce the impact toughness of the weld metal. Therefore, in the present invention, the content of P and S is controlled at S≤0.025wt%, P≤0.025wt%.

[0011] The Ni element can increase the hardenability of the weld metal, thereby increasing the content of the hardened phase in the weld area, improving the hardness and strength of the weld, and improving the plasticity and toughness of the weld by refining the grains, and reducing the toughness-brittle transition temperature and improving its impact toughness. If the Ni content is too high, the hardenability of the weld metal will be improved, the content of martensite will increase, the impact toughness of the weld metal will be reduced, and the crack sensitivity will be increased. Therefore, the present invention controls the Ni content to 2.80-3.10wt%.

[0012] The addition of Mo element helps to form hardened structures such as bainite and martensite, effectively improving the strength and hardness of weld metal. In addition, the addition of Mo element promotes the formation of fine grain structure of weld metal, which can simultaneously improve the tensile strength and low temperature impact toughness of the weld, so that the strength and toughness of the weld metal can be optimally matched. However, a higher Mo content increases product cost and reduces the toughness and plasticity of weld metal. In order to ensure the comprehensive mechanical properties and economy of weld metal, the Mo content of the present invention is controlled at 0.50-0.85wt%.

[0013] The Cr element has a strong affinity with carbon atoms and is easy to form chromium carbide compounds. Chromium carbide is an interstitial compound that reduces the proportion of other interstitial phases with higher hardness, thereby improving the plasticity and toughness of the weld metal. It can effectively increase the stability of austenite, reduce the precipitation of supersaturated carbides, increase the strength and hardness of the weld metal after welding, and reduce plasticity and toughness. Therefore, the Cr element content must be guaranteed to be within a certain range. The present invention controls the Cr content in the range of 1.05-1.40wt%.

[0014] The addition of Cr and Mo elements will increase the surface tension of molten iron, and when added to a certain amount, it will affect the weld formation and performance. The Ni element has a lower surface tension in the molten state, which has the effect of reducing the surface tension of molten iron and improving the weld formation. Therefore, the addition amount of Cr and Mo and the Ni element must meet a certain relative relationship. 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.

[0015] The Cu element has good electrical conductivity, and its electrical conductivity is better than that of steel. Therefore, during welding, Cu can improve the overall electrical conductivity of the welding wire, which helps the stable burning of the arc and the transmission of current during welding. However, excessive Cu content will form segregation, resulting in a decrease in the plastic toughness of the weld metal and an increase in material cost. The Cu content of the present invention is controlled at 0.20-0.30wt%.

[0016] 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.

[0017] 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 be used as a crystallization core to promote nucleation and refine the weld grains, thereby improving the toughness and plasticity of the weld and reducing the harmful effects of solid solution N. Ti is also an effective deoxidizer that forms a stable compound with oxygen in the air, reduces pores and inclusions in the weld, and improves 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%.

[0018] V is a strong carbide-forming element, which reacts with C to form VC particles, which can be effectively dispersed in the weld. These particles can improve the strength and toughness of the weld. V can also improve the wettability of the weld metal and reduce the formation of pores, thereby improving the overall quality of the weld. However, too high V ash causes the toughness of the weld metal to drop sharply, affecting the comprehensive mechanical properties of the weld. Therefore, the V content of the present invention is controlled at 0.020-0.060wt%.

[0019] Because Ti and V are strong carbide-forming elements, their affinity for C is greater than that of Cr. When Ti and V are added, they first react with C to form carbides, thereby reducing the amount of chromium carbide and increasing the ratio of interstitial phases and interstitial compounds, which reduces the plastic toughness of the weld metal. If the content of Ti and V is reduced, although the content of carbides is reduced, the grain refinement effect is reduced. Therefore, the effects of Cr, Ti, and V in the weld metal affect each other, and the addition ratio of the three elements should be appropriate to achieve the best effect. 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.

[0020] The present invention also provides a method for preparing a solid welding wire for 1000MPa high-strength steel, the method comprising the following steps: using a wire rod containing the above-mentioned weight percentage chemical composition, and sequentially subjecting it to complete annealing treatment, pre-drawing, spheroidizing annealing treatment, rough drawing, spheroidizing annealing treatment, fine drawing and copper plating treatment to make a finished solid welding wire.

[0021] Further, the diameter of the solid welding wire is 1.0-1.2 mm.

[0022] Furthermore, the conditions for complete annealing are: temperature 870-890° C., time 10 h-11 h.

[0023] Furthermore, the conditions of the two spheroidizing annealings are: temperature 760-790°C, time 10h-11h.

[0024] 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 in the range of 10-11 hours.

[0025] The wire rod used in the present invention not only has a high alloy content, but also has an original structure dominated by hard and brittle phases, and is severely work hardened. During the continuous drawing process, the drawability of the wire rod will be sharply reduced. If annealing is not performed or the number of annealing is insufficient, the wire will frequently break during drawing, resulting in the inability to carry out production. Therefore, annealing must be performed before pre-drawing to improve the drawability of the wire rod. After pre-drawing and rough drawing, secondary and tertiary annealing must also be performed to improve the deformation structure of the wire rod after drawing, enhance its cold workability, and prevent wire breakage during drawing from causing the inability to produce smoothly. Therefore, the present invention uses two different annealing methods and uses them in different production links respectively.

[0026] The principle is as follows: the wire rod arrives at the factory in a hot-rolled state, without lattice deformation caused by cold working. The purpose of annealing is to eliminate martensite, bainite and other structures and reduce hardness. Therefore, a complete annealing process that can obtain a nearly balanced structure is selected. After drawing, the wire rod has undergone cold working deformation, and the structure has lattice deformation. The purpose of annealing is to increase its machinability, so spheroidizing annealing is required.

[0027] 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.

[0028] 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.

[0029] Furthermore, when the diameter of the welding wire used 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.

[0030] 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.

[0031] Under this welding method, the welding process can be ensured to be in a stable jet state, without the disturbance of the molten pool by short circuit and droplet transition, thus achieving stable weld metal properties.

[0032] Compared with the prior art, the solid welding wire for 1000MPa high-strength steel of the present invention has the following advantages: (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. The molten iron has good fluidity, the arc is stable, and the molding is beautiful.

[0033] (2) The method for preparing the solid welding wire for 1000 MPa high-strength steel described in 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 welding wire.

[0034] (3) The welding method of the solid welding wire for 1000MPa high-strength steel described in the present invention specifically solves the welding process problems caused by the high strength of this product. The use of this welding method can maximize the performance of the product of the present invention. DETAILED DESCRIPTION

[0035] 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.

[0036] 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 described embodiments 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 work are within the scope of protection of the present invention.

[0037] Example 1

[0038] A solid welding wire for 1000MPa high-strength steel, the chemical composition of the welding wire comprising, 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, 0.015wt% of S, a mass ratio of Cr to Ti+V of 11.3, a mass ratio of Ni to Cr+Mo of 1.67, and the balance being Fe and unavoidable impurities.

[0039] The preparation method of the welding wire is: using a wire rod containing the above percentage of chemical composition to perform complete annealing treatment-pre-drawing-spheroidizing annealing treatment-rough drawing-spheroidizing annealing treatment-fine drawing-copper plating treatment to prepare a 1.2 mm finished solid welding wire.

[0040] The full annealing process is 870℃×10h, and the spheroidizing annealing process is 790℃×10h.

[0041] The metal-metal gas shielded welding method is adopted, the welding test plate is 20 mm thick, and the invented product is used as the base material for edging 2 mm thick.

[0042] The groove form of the welding test plate is Y-shaped, and the groove angle on one side is 10°.

[0043] 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.

[0044] In this embodiment: the welding current is 280-300A, the arc voltage is 29V, the welding speed is 32cm / min, the interlayer temperature is 140°C-160°C, and the welding line energy is 14.7KJ / cm.

[0045] 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 was well formed, which is comparable to the existing G49A4UM21S6 (ER70S-6) product level with better process performance.

[0046] Example 2

[0047] A solid welding wire for 1000MPa high-strength steel, the chemical composition of which, by weight percentage, comprises: 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, 0.020wt% of S, a mass ratio of Cr to Ti+V of 11.58, a mass ratio of Ni to Cr+Mo of 1.79, and the balance of Fe and unavoidable impurities.

[0048] 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.

[0049] The welding method of the welding wire is also the same as that of the first embodiment.

[0050] The weld metal after welding in this embodiment was tested, 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, and the welding processability was good.

[0051] Example 3

[0052] A solid welding wire for 1000MPa high-strength steel, the chemical composition of which, by weight percentage, comprises: 0.10wt% of C, 2.05wt% of Mn, 0.74wt% of Si, 1.21wt% of Cr, 3.05wt% of Ni, 0.70wt% of Mo, 0.080wt% of Ti, 0.040wt% of V, 0.25wt% of Cu, 0.015wt% of P, 0.020wt% of S, a mass ratio of Cr to Ti+V of 10.08, a mass ratio of Ni to Cr+Mo of 1.60, and the balance of Fe and unavoidable impurities.

[0053] 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.

[0054] The same metal arc welding method as in Example 1 was used, but the specific welding parameters were different, as follows: 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.

[0055] The weld metal after welding in this embodiment was tested, 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, and the welding processability was good.

[0056] Example 4

[0057] A solid welding wire for 1000MPa high-strength steel, the chemical composition of which, by weight percentage, comprises: 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, 0.014wt% of S, a mass ratio of Cr to Ti+V of 11.81, a mass ratio of Ni to Cr+Mo of 1.51, and the balance of Fe and unavoidable impurities.

[0058] 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.

[0059] The welding method of the welding wire is also the same as that of the first embodiment.

[0060] 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, and the welding processability was good.

[0061] Example 5

[0062] A solid welding wire for 1000MPa high-strength steel, the chemical composition of which is calculated by weight percentage: C is 0.098wt%, Mn is 2.00wt%, Si is 0.75wt%, Cr is 1.34wt%, Ni is 3.08wt%, Mo is 0.65wt%, Ti is 0.070wt%, V is 0.042wt%, Cu is 0.21wt%, P is 0.023wt%, S is 0.015wt%, 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.

[0063] 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.

[0064] The welding method of the welding wire is the same as that of Example 3.

[0065] The weld metal after welding in this embodiment was tested, 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, and the welding processability was good.

[0066] Comparative Example 1 The mass ratio of Cr to Ti+V is different A solid welding wire for 1000MPa high-strength steel, the chemical composition of the welding wire comprising, 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, 0.015wt% of S, a mass ratio of Cr to Ti+V of 8.92, a mass ratio of Ni to Cr+Mo of 1.67, and the balance being Fe and unavoidable impurities.

[0067] 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.

[0068] The welding method of the welding wire is also the same as that of the first embodiment.

[0069] The weld metal after welding in this embodiment was tested, 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, and the welding processability was good.

[0070] Comparative Example 2 The mass ratio of Cr to Ti+V is different A solid welding wire for 1000MPa high-strength steel, the chemical composition of the welding wire comprising, 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, 0.015wt% of S, a mass ratio of Cr to Ti+V of 15.29, a mass ratio of Ni to Cr+Mo of 1.67, and the balance being 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 after welding in this embodiment was tested, 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, and the welding processability was good.

[0074] Comparative Example 3 Different Ni and Cr+Mo mass ratios A solid welding wire for 1000MPa high-strength steel, the chemical composition of the welding wire comprising, 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, 0.015wt% of S, a mass ratio of Cr to Ti+V of 11.3, a mass ratio of Ni to Cr+Mo of 1.46, and the balance being Fe and unavoidable impurities.

[0075] 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.

[0076] The welding method of the welding wire is also the same as that of the first embodiment.

[0077] The weld metal after welding in this embodiment was tested, 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.

[0078] Comparative Example 4 Ni and Cr+Mo mass ratios are different A solid welding wire for 1000MPa high-strength steel, the chemical composition of the welding wire comprising, 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, 0.015wt% of S, a mass ratio of Cr to Ti+V of 11.3, a mass ratio of Ni to Cr+Mo of 1.97, and the balance being Fe and unavoidable impurities.

[0079] 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.

[0080] The welding method of the welding wire is also the same as that of the first embodiment.

[0081] The weld metal after welding in this embodiment was tested, 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.

[0082] Comparative Example 5 Different Cr Content A solid welding wire for 1000MPa high-strength steel, the chemical composition of the welding wire comprising, 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, 0.015wt% of S, a mass ratio of Cr to Ti+V of 11.25, a mass ratio of Ni to Cr+Mo of 1.67, and the balance being Fe and unavoidable impurities.

[0083] 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.

[0084] The welding method of the welding wire is also the same as that of the first embodiment.

[0085] The weld metal after welding in this embodiment was tested, 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, and the welding processability was good.

[0086] Comparative Example 6 Different Cr Contents A solid welding wire for 1000MPa high-strength steel, the chemical composition of the welding wire comprising, 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, 0.015wt% of S, a mass ratio of Cr to Ti+V of 11.27, a mass ratio of Ni to Cr+Mo of 1.67, and the balance being Fe and unavoidable impurities.

[0087] 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.

[0088] The welding method of the welding wire is also the same as that of the first embodiment.

[0089] The weld metal after welding in this embodiment was tested, 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, and the welding processability was good.

[0090] Comparative Example 7 Different preparation methods The chemical composition of the welding wire is the same as that of Example 1.

[0091] The preparation method of the welding wire only uses full annealing, specifically: using a wire rod containing the above percentage chemical composition, the design process is full annealing-pre-drawing-full annealing-rough drawing-full annealing-fine drawing-copper plating, but the wire rod frequently breaks during the rough drawing process, and normal production cannot be achieved. This is because the wire rod has a high alloy component content, and the pre-drawing increases the tendency of component segregation, resulting in the formation of hardened structure in some areas of the wire rod.

[0092] Comparative Example 8 Different preparation methods The chemical composition of the welding wire is the same as that of Example 1.

[0093] The preparation method of the welding wire only uses spheroidizing annealing, specifically: using a wire rod containing the above percentage chemical composition, the design process is spheroidizing annealing-pre-drawing-spheroidizing annealing-rough drawing-spheroidizing annealing-fine drawing-copper plating, but the wire rod frequently breaks during the pre-drawing process, and normal production cannot be achieved. This is because the wire rod has a high alloy component content and good hardenability, resulting in the wire rod entering the factory with a hardened phase dominated by martensite, so after spheroidizing annealing, a balanced state structure that is conducive to drawing cannot be obtained.

[0094] Comparative Example 9 Different preparation methods The chemical composition of the welding wire is the same as that of Example 1.

[0095] The preparation method of the welding wire uses a different annealing sequence, specifically: the wire rod containing the above percentage chemical composition is designed to be: spheroidizing annealing-pre-drawing-complete annealing-rough drawing-complete annealing-fine drawing-copper plating, and the same problem as that of comparative example 8 occurs, and the wire rod frequently breaks during the pre-drawing process, and normal production cannot be achieved. This is also because the equilibrium state structure that is conducive to drawing cannot be obtained after spheroidizing annealing.

[0096] Table 1 Performance comparison of each embodiment and each comparative example

[0097] By comparing the examples and comparative examples 1-2, it can be found that although the weight percentages of the chemical components are within the required range, the mass ratio of Cr to Ti+V does not meet the requirements, that is, the mass ratio of Cr to Ti+V in comparative example 1 is less than 10, and the mass ratio of Cr to Ti+V in comparative example 2 is greater than 13, and the elongation and -40°C impact energy of the welding wire are significantly reduced. Because Ti and V are strong carbide-forming elements, their affinity for C is greater than that of Cr. When Ti and V are added, they first react with C to form carbides, thereby reducing the amount of chromium carbide, increasing the ratio of interstitial phases to interstitial compounds, and reducing the plastic toughness of the weld metal. If the content of Ti and V is reduced, although the carbide content is reduced, the grain refinement effect is reduced. Therefore, the three elements Cr, Ti, and V in the weld metal affect each other, and the addition ratio must be appropriate to achieve the best effect.

[0098] By comparing the examples and comparative examples 3-4, it can be found that although the weight percentage of each chemical component is within the required range, the mass ratio of Ni to Cr+Mo does not meet the requirements, that is, 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, and the molten iron has poor fluidity and poor welding forming. This is because the addition of Cr and Mo elements will increase the surface tension of molten iron, and when added to a certain amount, it will affect the weld forming and performance. Ni element has a lower surface tension in the molten state, which has the effect of reducing the surface tension of molten iron and improving weld forming. Therefore, the addition amount of Cr and Mo must meet a certain relative relationship with the Ni element to achieve the best effect.

[0099] By comparing comparative examples 5-6, it can be found that although the mass ratio of Cr to Ti+V and the mass ratio of Ni to Cr+Mo meet the requirements, too low or too high Cr content is not conducive to improving the performance of the welding wire. This is because in high-strength welding wires with more alloy elements, due to good permeability and high content of hardened phase, the plastic toughness is poor. The addition of Cr will increase carbide precipitation and refine the grain while improving permeability, thereby improving plastic toughness. However, the content of Cr, the mass ratio of Cr to Ti+V, and the mass ratio of Ni to Cr+Mo must meet the proportional relationship at the same time to achieve better results.

[0100] It can be concluded from Comparative Examples 1-6 that welding wire with better performance can only be prepared when the weight percentage of each chemical component is within the required range and the mass ratio of Cr to Ti+V and the mass ratio of Ni to Cr+Mo also meet the requirements.

[0101] 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 using a single annealing method or changing the annealing sequence, cannot produce welding wire normally.

[0102] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A solid welding wire for 1000MPa high-strength steel, characterized in that: 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 controlled to be ≥10, and the mass ratio of Ni to Cr+Mo is controlled to be ≥1.5; the sum of inevitable impurity elements is ≤0.3wt%, and the balance is Fe.

2. The solid welding wire for 1000MPa high-strength steel according to claim 1, characterized in that: 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.

3. A method for preparing a solid welding wire for 1000MPa high-strength steel, characterized in that: The method comprises the following steps: using a wire rod containing the weight percentage chemical composition described in any one of claims 1-2, and sequentially subjecting it to complete annealing, pre-drawing, spheroidizing annealing, rough drawing, spheroidizing annealing, fine drawing and copper plating to produce a finished solid welding wire.

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

5. The method for preparing a solid welding wire for 1000MPa high-strength steel according to claim 3, characterized in that: The conditions for complete annealing are: temperature 870-890°C, time 10h-11h.

6. The method for preparing a solid welding wire for 1000MPa high-strength steel according to claim 3, characterized in that: The conditions for the two spheroidizing annealings are: temperature 760-790°C, time 10h-11h.

7. A welding method for a solid welding wire for 1000MPa high-strength steel according to any one of claims 1 to 2, 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.

8. The welding method of the solid welding wire for 1000MPa high-strength steel according to claim 7, 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.

9. The welding method of the solid welding wire for 1000MPa high-strength steel according to claim 7, 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.

Images