960MPa-grade high-strength gas shielded solid welding wire and preparation method thereof

Abstract

The invention belongs to the field of solid welding wires, and provides a 960MPa-grade high-strength gas shielded solid welding wire and a preparation method thereof, the solid welding wire comprises the following components by weight percent: 0.03-0.11 wt% of C; mn is 1.60 to 1.90 wt%; si is 0.40 to 0.80 wt%; p is less than or equal to 0.010 wt%; s is less than or equal to 0.010 wt%; 0.20 to 0.50 wt% of Cr; ni is 2.00 to 2.50 wt%; 0.40 to 1.00 wt% of Mo; 0.050 to 0.110 wt% of Ti; 0.04 to 0.08 wt% of Al; the content of O is 0.0060 to 0.010 percent by weight; the sum of the inevitable impurity elements is not more than 0.3 wt%; and the balance of Fe. According to the 960MPa-grade high-strength gas shielded solid welding wire, deposited metal has good obdurability, and welding of high-strength steel with the strength grade of 960MPa or above can be met; meanwhile, a smelting method for controlling the oxygen content and an improved welding wire preparation method are provided, and the quality of a welding wire product can be improved.

Description

Technical Field

[0001] The invention belongs to the field of solid welding wires, and in particular relates to a 960MPa-grade high-strength gas-shielded solid welding wire and a preparation method thereof. Background Art

[0002] As domestic and foreign engineering machinery, coal machinery, marine equipment, hydropower equipment, etc. develop towards high quality, high strength, high toughness, large-scale and lightweight, welding metal materials have expanded from traditional carbon steel and low alloy steel to the field of high-strength steel. Welding is an indispensable processing and manufacturing link for the promotion and application of high-strength steel. The promotion and application of high-strength steel in the field of machinery manufacturing has also promoted the rapid development of the high-strength gas-shielded solid welding wire industry. Therefore, the development of matching welding materials and production processes for high-strength steel is the key to obtaining high-quality welded joints. However, solid welding wire for high-strength steel faces a series of technical challenges in the manufacturing and application process, including wire rod smelting, production drawing process, and microstructure regulation.

[0003] During the production process, solid welding wire needs to go through a wire drawing process. The higher the strength, the lower the toughness of the wire rod raw material, the plasticity cannot be effectively guaranteed, and the drawability is reduced. This puts higher requirements on the production drawing process of solid welding wire, and there are various difficulties in high-strength gas-shielded solid welding wire. Summary of the invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and proposes a 960MPa grade high-strength gas-shielded solid welding wire and a preparation method thereof.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows: The present invention provides a 960MPa grade high-strength gas shielded solid welding wire, which comprises the following components in weight percentage: C 0.03-0.11wt%; Mn 1.60-1.90wt%; Si 0.40-0.80wt%; P≤0.010wt%; S≤0.010wt%; Cr 0.20-0.50wt%; Ni 2.00-2.50wt%; Mo 0.40-1.00wt%; Ti 0.050-0.120wt%; Al0.04-0.08wt%; O 0.0060-0.010wt%; The total of unavoidable impurity elements ≤0.3wt%; The balance is Fe.

[0006] Furthermore, the mass ratio of Cr to Mo is 0.45-0.55:1.

[0007] Furthermore, the mass ratio of O to Ni is ≤0.004.

[0008] Furthermore, the mass ratio of O to Al is ≤0.16wt%.

[0009] The present invention also provides a method for preparing a 960MPa grade high-strength gas shielded solid welding wire, which is characterized by comprising the following steps: Step 1 is to smelt pig iron to obtain wire rods; Step 2 is to sequentially perform pre-drawing, primary spheroidizing annealing, rough drawing, secondary spheroidizing annealing, fine drawing, and copper plating on the wire rod to obtain the solid welding wire.

[0010] Furthermore, the smelting in step 1 comprises the following steps: The pig iron is subjected to converter steelmaking and then enters an LF furnace for refining, an intermediate alloy is added to the LF furnace, and the wire rod is obtained after the refining is completed.

[0011] Furthermore, the oxygen content of the material discharged from the converter steelmaking step is 300-800 ppm; and the temperature of the refining step is 1530-1580°C.

[0012] Furthermore, the oxygen content of the master alloy is 60-120 ppm; the master alloy includes the following components in weight percentage: C≤0.05wt%, S≤0.006wt%, P≤0.005wt%, O: 0.006-0.012wt%, and the balance is Fe; the master alloy accounts for 0.1-0.5wt% of the mass of the pig iron. The addition of the master alloy ensures that the welding wire composition meets the required oxygen content.

[0013] Furthermore, the temperature of the first spheroidizing annealing treatment is 750-770°C, and the time is 10-11 hours; the temperature of the second spheroidizing annealing treatment is 750-770°C, and the time is 10-11 hours.

[0014] Pre-drawing before annealing can reduce the compression ratio of the wire rod after spheroidizing annealing, reduce the difficulty of drawing, and pre-drawing can remove the oxide scale on the surface of the wire rod, so that the surface of the wire rod after spheroidizing annealing can be better cleaned. Since the carbide crushing after pre-drawing serves as the core of annealing nucleation, and the plastic deformation of steel can accumulate a certain amount of energy as the driving force for the organizational change during the annealing process. Therefore, the drawing process is conducive to the nucleation of the next annealing process. The present invention sets the spheroidizing annealing process to 760℃×10h and then slow cooling.

[0015] Furthermore, the yield strength of the solid welding wire is ≥890MPa, the tensile strength is ≥960MPa, the elongation A is ≥14%, and the -40℃ impact toughness is ≥47J. In addition, the molten iron has good fluidity, the arc is stable, and the molding is beautiful. The functions of the chemical components are as follows: C can improve the strength and hardness of weld metal through its solid solution strengthening effect, and can improve the hardenability of weld metal, making it easier to obtain high-strength structure, indirectly improving strength and hardness, but at the same time reducing plasticity and toughness. The increase of C will also lead to poor welding performance. Hot cracks and cold cracks are easy to occur during welding of high-carbon molten metal, which seriously affects the welding quality.

[0016] Mn is a deoxidizer and desulfurizer in weld metal, which can prevent the reaction of weld metal with oxygen and sulfur, reduce the tendency of thermal cracks caused by sulfur, and thus improve welding performance. Mn also helps to refine the grain structure of the weld joint, promote the formation of acicular ferrite, and improve the comprehensive mechanical properties of the weld metal, including strength and toughness. However, the increase in Mn content will affect the carbon equivalent, and the increase in carbon equivalent will lead to poor weldability. At the same time, the Mn fume generated during welding is not good for the health of welders.

[0017] The Si element is a deoxidizer for the weld, which can reduce the combination of iron and oxygen during welding and increase the fluidity of molten iron, which helps to improve the quality of weld metal. However, excessive fluidity of molten iron can cause splashing, affecting welding quality and efficiency. Silicon can be dissolved in the weld structure and play a role in solid solution strengthening, thereby improving the strength of the weld, but it also reduces the plasticity and toughness of the weld.

[0018] P and S are harmful elements in the deposited metal, which will significantly reduce the toughness and plasticity of the welded joint. This is because P will cause cold brittleness in the weld, and P will also increase the crack sensitivity during welding. S is almost insoluble in steel, but forms compounds with iron, mainly in the form of FeS, especially when the liquid metal solidifies, it is easy to form a low-melting point eutectic, which is distributed at the grain boundary, increasing the tendency of hot cracks while reducing impact toughness.

[0019] The Ni element can refine the grains of the weld metal, leading to an increase in acicular ferrite in the organization, and reduce the ductile-brittle transition temperature, improve its impact toughness, and enhance the hardenability of the weld metal, thereby improving the strength of the weld metal to a certain extent. When the Ni content increases to a certain amount, the hardenability of the weld metal is improved. With the increase in tensile strength, the acicular ferrite decreases, and bainite or even martensite appears, reducing the impact toughness of the weld metal. In addition, the cost of Ni is relatively high compared to other elements.

[0020] Cr and Mo are the main elements to improve the strength of weld metal. Both Cr and Mo can greatly improve the hardenability of weld metal. With the increase of element content, the weld structure changes, the proeutectoid ferrite and acicular ferrite decrease, the proportion of bainite increases, and even martensite structure appears, which will increase the strength of the weld joint and reduce the impact toughness. Therefore, the element content must be guaranteed to be within a certain range. Mo can also ensure that the welding wire has sufficient strength and toughness matching by refining the weld grains. Cr is easy to form stable carbides with carbon in the alloy. If the content is too high, it will increase the sensitivity of hot cracks during welding. Therefore, Mo is the main strength-forming element in the alloy, but due to its high cost, it can be replaced by a partial content of Cr to play a strengthening role, but the Cr content needs to be strictly controlled.

[0021] In order to ensure the comprehensive mechanical properties of the weld metal, the present invention adds the strong carbide-forming element Ti by means of microalloying. The Ti element can form TiN particles, which can effectively prevent the growth of austenite grains during the welding thermal cycle, and play a role in refining the grains and thus improving the toughness of the welded joint. However, the presence of excessive Ti elements in molten iron will affect the fluidity of the molten iron, making the molten iron viscous.

[0022] Al is a strong deoxidizer, which can effectively reduce the oxygen content in the weld metal. Al can also combine with nitrogen to form AlN, which helps to reduce the generation of nitrogen pores and reduce the tendency of delayed cracking in the weld. AlN is a small particle that is not easily dissolved. It is distributed in the molten pool to hinder the growth of grains during the crystallization process, and plays a role in refining the weld metal structure and improving the comprehensive mechanical properties. Too high Al content can reduce the heat cracking resistance of the weld metal.

[0023] The O element can improve the fluidity of the molten iron in the molten pool by reducing the surface tension in the molten pool during welding. In order to control the quality of the weld, the product of the present invention has high requirements for the S and P contents, resulting in poor fluidity of the molten iron in the weld, so it is necessary to add some O elements to enhance the fluidity of the molten iron. However, with the increase of oxygen content in the weld, strength, hardness, plasticity and toughness will all decrease, which will cause the Ni content to increase. In addition, the melting point of Al oxide Al2O3 is very high. If it is present in the weld in a solid state, it is very easy to cause weld slag inclusion. Affect the plastic toughness of the weld, so the content of O should be controlled after the Al element is increased to a certain amount.

[0024] Compared with the prior art, the present invention has the following advantages: The 960MPa high-strength gas-shielded solid welding wire of the present invention has good toughness in its deposited metal, which can meet the welding of high-strength steels of 960MPa and above strength levels; at the same time, a smelting method for controlling oxygen content and an improved method for preparing welding wire are provided, which can improve the quality of welding wire products. DETAILED DESCRIPTION

[0025] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0026] The present invention will be described in detail below with reference to the embodiments.

[0027] Example 1

[0028] A 960MPa grade high strength gas shielded solid welding wire, the solid welding wire comprises the following components in weight percentage: C is 0.085wt%, Mn is 1.75wt%, Si is 0.45wt%, Cr is 0.25wt%, Ni is 2.15wt%, Mo is 0.50wt%, Ti is 0.055wt%, Al is 0.045wt%, P is 0.015wt%, S is 0.020wt%, O is 0.0070wt%, and the balance is Fe and unavoidable impurities.

[0029] A method for preparing a 960MPa grade high-strength gas shielded solid welding wire comprises the following steps: Step 1 is to subject the pig iron to converter steelmaking, the oxygen content of the pig iron out of the furnace is 450ppm, and then enter the LF furnace for refining at a temperature of 1550°C, add a master alloy in the LF furnace (the oxygen content of the master alloy is 80ppm; the master alloy includes the following weight percentage components: C: 0.04wt%, S: 0.005wt%, P: 0.004wt%, 0: 0.011wt%, and the balance is Fe; the master alloy accounts for 0.3wt% of the mass of the pig iron), and obtain the wire rod after refining; Step 2 is to pre-draw the wire rod, perform a spheroidizing annealing at 760°C × 10h, perform rough drawing, perform a secondary spheroidizing annealing at 760°C × 10h, perform fine drawing, and perform copper plating in sequence to obtain a 1.2mm solid welding wire.

[0030] The welding method of metal arc welding is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material edge 2mm thick. The groove form of the welding test plate is V-shaped, and the single-side groove angle is 10°. The shielding gas used is a mixed gas: 80vol%Ar+20vol%CO2, and the gas flow rate is 15-20L / min.

[0031] In this embodiment: the welding current is 280-300A, the arc voltage is 28-30V, the welding speed is 30-42cm / min, and the welding line energy is 11.2-12.9KJ / cm.

[0032] The yield strength of the weld metal after welding in this embodiment is tested to be 894 MPa, the tensile strength is 985 MPa, the elongation A=16.5%, the average impact energy Akv=70-85 J at -40°C, and the welding processability is good.

[0033] Example 2

[0034] A 960MPa grade high strength gas shielded solid welding wire, the solid welding wire comprises the following components in weight percentage: C is 0.095wt%, Mn is 1.80wt%, Si is 0.55wt%, Cr is 0.30wt%, Ni is 2.25wt%, Mo is 0.55wt%, Ti is 0.070wt%, Al is 0.055wt%, P is 0.022wt%, S is 0.018wt%, O is 0.0075wt%, and the balance is Fe and unavoidable impurities.

[0035] The preparation method of a 960MPa grade high-strength gas shielded solid welding wire is the same as that in Example 1.

[0036] The welding method of metal arc welding is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material edge 2mm thick. The groove form of the welding test plate is V-shaped, and the single-side groove angle is 10°. The shielding gas used is a mixed gas: 80vol%Ar+20vol%CO2, and the gas flow rate is 15-20L / min.

[0037] In this embodiment: the welding current is 280-300A, the arc voltage is 28-30V, the welding speed is 30-42cm / min, and the welding line energy is 11.2-12.9KJ / cm.

[0038] The yield strength of the weld metal after welding in this embodiment was tested to be 908 MPa, the tensile strength was 1003 MPa, the elongation A=15.5%, and the average impact energy Akv=64-82 J at -40°C, indicating good welding processability.

[0039] Example 3

[0040] A 960MPa grade high strength gas shielded solid welding wire, the solid welding wire comprises the following components in weight percentage: C is 0.10wt%, Mn is 1.85wt%, Si is 0.68wt%, Cr is 0.35wt%, Ni is 2.35wt%, Mo is 0.70wt%, Ti is 0.085wt%, Al is 0.065wt%, P is 0.020wt%, S is 0.015wt%, O is 0.0090wt%, and the balance is Fe and unavoidable impurities.

[0041] The preparation method of a 960MPa grade high-strength gas shielded solid welding wire is the same as that in Example 1, and a 1.0 mm finished solid welding wire is prepared.

[0042] In this embodiment: the welding current is 240-270A, the arc voltage is 26-28V, the welding speed is 24-33cm / min, and the welding line energy is 11.3-16.8KJ / cm.

[0043] The yield strength of the weld metal after welding in this embodiment is tested to be 899 MPa, the tensile strength is 1020 MPa, the elongation A=14.5%, the average impact energy Akv=55-73 J at -40°C, and the welding processability is good.

[0044] Example 4

[0045] A 960MPa grade high strength gas shielded solid welding wire, the solid welding wire comprises the following components in weight percentage: C is 0.105wt%, Mn is 1.85wt%, Si is 0.75wt%, Cr is 0.45wt%, Ni is 2.45wt%, Mo is 0.85wt%, Ti is 0.105wt%, Al is 0.065wt%, P is 0.015wt%, S is 0.015wt%, O is 0.0083wt%, and the balance is Fe and unavoidable impurities.

[0046] The preparation method of a 960MPa grade high-strength gas shielded solid welding wire is the same as that in Example 1.

[0047] The welding method of metal arc welding is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material edge 2mm thick. The groove form of the welding test plate is V-shaped, and the single-side groove angle is 10°. The shielding gas used is a mixed gas: 80vol%Ar+20vol%CO2, and the gas flow rate is 15-20L / min.

[0048] In this embodiment: the welding current is 280-300A, the arc voltage is 28-30V, the welding speed is 30-42cm / min, and the welding line energy is 11.2-12.9KJ / cm.

[0049] The yield strength of the weld metal after welding in this embodiment is tested to be 893 MPa, the tensile strength is 1025 MPa, the elongation A=15.0%, the average impact energy Akv=60-85 J at -40°C, and the welding processability is good.

[0050] Example 5

[0051] A 960MPa grade high strength gas shielded solid welding wire, the solid welding wire comprises the following components in weight percentage: C is 0.098wt%, Mn is 1.70wt%, Si is 0.65wt%, Cr is 0.38wt%, Ni is 2.37wt%, Mo is 0.74wt%, Ti is 0.090wt%, Al is 0.062wt%, P is 0.013wt%, S is 0.022wt%, O is 0.0085wt%, and the balance is Fe and unavoidable impurities.

[0052] The preparation method of a 960MPa grade high-strength gas shielded solid welding wire is the same as that in Example 1.

[0053] The welding method of metal arc welding is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material edge 2mm thick. The groove form of the welding test plate is V-shaped, and the single-side groove angle is 10°. The shielding gas used is a mixed gas: 80vol%Ar+20vol%CO2, and the gas flow rate is 15-20L / min.

[0054] In this embodiment: the welding current is 240-270A, the arc voltage is 26-28V, the welding speed is 24-33cm / min, and the welding line energy is 11.3-16.8KJ / cm.

[0055] The yield strength of the weld metal after welding in this embodiment was tested to be 911 MPa, the tensile strength was 1010 MPa, the elongation A=15.2%, and the average impact energy Akv=68-87 J at -40°C, and the welding processability was good.

[0056] Comparative Example 1 A 960MPa grade high strength gas shielded solid welding wire, the solid welding wire comprises the following components in weight percentage: C is 0.085wt%, Mn is 1.75wt%, Si is 0.45wt%, Cr is 0.45wt%, Ni is 2.15wt%, Mo is 0.50wt%, Ti is 0.055wt%, Al is 0.045wt%, P is 0.015wt%, S is 0.020wt%, O is 0.0070wt%, and the balance is Fe and unavoidable impurities.

[0057] The preparation method of a 960MPa grade high-strength gas shielded solid welding wire is the same as that in Example 1.

[0058] The welding method of metal arc welding is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material edge 2mm thick. The groove form of the welding test plate is V-shaped, and the single-side groove angle is 10°. The shielding gas used is a mixed gas: 80vol%Ar+20vol%CO2, and the gas flow rate is 15-20L / min.

[0059] In this embodiment: the welding current is 280-300A, the arc voltage is 28-30V, the welding speed is 30-42cm / min, and the welding line energy is 11.2-12.9KJ / cm.

[0060] The yield strength of the weld metal after welding in this embodiment is tested to be 891 MPa, the tensile strength is 987 MPa, the elongation A=16.5%, and the average impact energy Akv=35-60 J at -40°C, but the welding processability is good.

[0061] Comparative Example 2 A 960MPa grade high strength gas shielded solid welding wire, the solid welding wire comprises the following components in weight percentage: C is 0.085wt%, Mn is 1.75wt%, Si is 0.45wt%, Cr is 0.25wt%, Ni is 2.15wt%, Mo is 0.50wt%, Ti is 0.055wt%, Al is 0.045wt%, P is 0.015wt%, S is 0.020wt%, O is 0.0090wt%, and the balance is Fe and unavoidable impurities.

[0062] The preparation method of a 960MPa grade high-strength gas shielded solid welding wire is the same as that in Example 1.

[0063] The welding method of metal arc welding is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material edge 2mm thick. The groove form of the welding test plate is V-shaped, and the single-side groove angle is 10°. The shielding gas used is a mixed gas: 80vol%Ar+20vol%CO2, and the gas flow rate is 15-20L / min.

[0064] In this embodiment: the welding current is 280-300A, the arc voltage is 28-30V, the welding speed is 30-42cm / min, and the welding line energy is 11.2-12.9KJ / cm.

[0065] The yield strength of the weld metal after welding in this embodiment is tested to be 900 MPa, the tensile strength is 1001 MPa, the elongation A=16.5%, and the average impact energy Akv=40-70 J at -40°C, but the welding processability is good.

[0066] Comparative Example 3 A 960MPa grade high strength gas shielded solid welding wire, the solid welding wire comprises the following components in weight percentage: C is 0.085wt%, Mn is 1.75wt%, Si is 0.45wt%, Cr is 0.25wt%, Ni is 2.15wt%, Mo is 0.50wt%, Ti is 0.055wt%, Al is 0.045wt%, P is 0.015wt%, S is 0.020wt%, O is 0.0085wt%, and the balance is Fe and unavoidable impurities.

[0067] The preparation method of a 960MPa grade high-strength gas shielded solid welding wire is the same as that in Example 1.

[0068] The welding method of metal arc welding is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material edge 2mm thick. The groove form of the welding test plate is V-shaped, and the single-side groove angle is 10°. The shielding gas used is a mixed gas: 80vol%Ar+20vol%CO2, and the gas flow rate is 15-20L / min.

[0069] In this embodiment: the welding current is 280-300A, the arc voltage is 28-30V, the welding speed is 30-42cm / min, and the welding line energy is 11.2-12.9KJ / cm.

[0070] The yield strength of the weld metal after welding in this embodiment is tested to be 887 MPa, the tensile strength is 976 MPa, the elongation A=16.5%, the average impact energy Akv=25-56 J at -40°C, and the welding processability is good.

[0071] Comparative Example 4 A 960MPa grade high-strength gas shielded solid welding wire, the proportion of which is the same as that of Example 1.

[0072] A method for preparing a 960MPa grade high-strength gas shielded solid welding wire comprises the following steps: Step 1 is to subject the pig iron to converter steelmaking, the oxygen content of the pig iron out of the furnace is 950ppm, and then enter the LF furnace for refining at a temperature of 1550°C, add a master alloy in the LF furnace (the oxygen content of the master alloy is 60-120ppm; the master alloy includes the following weight percentage components: C: 0.04wt%, S: 0.005wt%, P: 0.004wt%, 0: 0.011wt%, and the balance is Fe; the master alloy accounts for 0.4wt% of the mass of the pig iron), and obtain the wire rod after refining, but the oxygen content of the wire rod exceeds the standard, reaching 0.015%; Step 2 is to pre-draw the wire rod, perform a spheroidizing annealing at 760°C × 10h, perform rough drawing, perform a secondary spheroidizing annealing at 760°C × 10h, perform fine drawing, and perform copper plating in sequence to obtain a 1.2mm solid welding wire.

[0073] The welding method of metal arc welding is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material edge 2mm thick. The groove form of the welding test plate is V-shaped, and the single-side groove angle is 10°. The shielding gas used is a mixed gas: 80vol%Ar+20vol%CO2, and the gas flow rate is 15-20L / min.

[0074] In this embodiment: the welding current is 280-300A, the arc voltage is 28-30V, the welding speed is 30-42cm / min, and the welding line energy is 11.2-12.9KJ / cm.

[0075] The yield strength of the weld metal after welding in this embodiment was tested to be 905 MPa, the tensile strength was 1031 MPa, the elongation A=16.5%, the average impact energy Akv=25-55 J at -40°C, and the welding processability was good.

[0076] Comparative Example 5 A 960MPa grade high-strength gas shielded solid welding wire, the proportion of which is the same as that of Example 1.

[0077] A method for preparing a 960MPa grade high-strength gas shielded solid welding wire comprises the following steps: Step 1 is to carry out converter steelmaking on pig iron, the oxygen content of which is 530ppm, and then enter the LF furnace for refining at a temperature of 1565°C, and obtain the wire rod after the refining is completed; Step 2 is to pre-draw the wire rod, perform a spheroidizing annealing at 760°C × 10h, perform rough drawing, perform a secondary spheroidizing annealing at 760°C × 10h, perform fine drawing, and perform copper plating in sequence to obtain a 1.2mm solid welding wire.

[0078] The welding method of metal arc welding is adopted, the welding test plate is 20mm thick, and the invented product is used as the base material edge 2mm thick. The groove form of the welding test plate is V-shaped, and the single-side groove angle is 10°. The shielding gas used is a mixed gas: 80vol%Ar+20vol%CO2, and the gas flow rate is 15-20L / min.

[0079] In this embodiment: the welding current is 280-300A, the arc voltage is 28-30V, the welding speed is 30-42cm / min, and the welding line energy is 11.2-12.9KJ / cm.

[0080] The yield strength of the weld metal after welding in this embodiment was tested to be 910 MPa, the tensile strength was 1038 MPa, the elongation A=16.5%, and the average impact energy Akv=70-85 J at -40°C. The welding processability was poor, the molten iron fluidity was poor, and the welding formation was poor.

[0081] Comparative Example 6 A 960MPa grade high-strength gas shielded solid welding wire, the proportion of which is the same as that of Example 1.

[0082] A method for preparing a 960MPa grade high-strength gas shielded solid welding wire comprises the following steps: Step 1 is to subject the pig iron to converter steelmaking, the oxygen content of the pig iron out of the furnace is 590ppm, and then enter the LF furnace for refining at a temperature of 1570°C, add a master alloy in the LF furnace (the oxygen content of the master alloy is 80ppm; the master alloy includes the following weight percentage components: C: 0.04wt%, S: 0.005wt%, P: 0.004wt%, 0: 0.011wt%, and the balance is Fe; the master alloy accounts for 0.35wt% of the mass of the pig iron), and obtain the wire rod after refining; Step 2 is to sequentially perform pre-drawing, spheroidizing annealing at 760°C × 10h, rough drawing, fine drawing, copper plating and other production processes on the wire rod. The rough drawing process after spheroidizing annealing proceeds smoothly, but the wire rod is subjected to tensile force after rough drawing, resulting in plastic deformation and work hardening, which causes frequent wire breakage during fine drawing due to insufficient plasticity of the wire rod, and subsequent production of finished welding wire is impossible.

[0083] 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 960MPa grade high strength gas shielded solid welding wire, characterized in that: The solid welding wire includes the following components in weight percentage: C 0.03-0.11wt%; Mn 1.60-1.90wt%; Si 0.40-0.80wt%; P≤0.010wt%; S≤0.010wt%; Cr0.20-0.50wt%; Ni 2.00-2.50wt%; Mo 0.40-1.00wt%; Ti 0.050-0.120wt%; Al 0.04-0.08wt%; O 0.0060-0.010wt%; The total of unavoidable impurity elements ≤0.3wt%; The balance is Fe.

2. The 960MPa grade high strength gas shielded solid welding wire according to claim 1, characterized in that: The mass ratio of Cr to Mo is 0.45-0.55:

1.

3. The 960MPa grade high strength gas shielded solid welding wire according to claim 1, characterized in that: The mass ratio of O to Ni is ≤0.

004.

4. The 960MPa grade high strength gas shielded solid welding wire according to claim 1, characterized in that: The mass ratio of O to Al is ≤0.16 wt%.

5. The method for preparing the 960MPa grade high strength gas shielded solid welding wire according to any one of claims 1 to 4, characterized in that: The steps include: Step 1 is to smelt pig iron to obtain wire rods; Step 2 is to sequentially perform pre-drawing, primary spheroidizing annealing, rough drawing, secondary spheroidizing annealing, fine drawing, and copper plating on the wire rod to obtain the solid welding wire.

6. The method for preparing the 960MPa grade high strength gas shielded solid welding wire according to claim 5, characterized in that: The smelting in step 1 comprises the following steps: The pig iron is subjected to converter steelmaking and then enters an LF furnace for refining, an intermediate alloy is added to the LF furnace, and the wire rod is obtained after the refining is completed.

7. The method for preparing the 960MPa grade high strength gas shielded solid welding wire according to claim 6, characterized in that: The oxygen content of the material discharged from the converter steelmaking step is 300-800ppm; the temperature of the refining step is 1530-1580℃.

8. The method for preparing the 960MPa grade high strength gas shielded solid welding wire according to claim 6, characterized in that: The oxygen content of the intermediate alloy is 60-120ppm; the intermediate alloy comprises the following components in weight percentage: C≤0.05wt%, S≤0.006wt%, P≤0.005wt%, O: 0.006-0.012wt%, and the balance is Fe; the mass percentage of the intermediate alloy in pig iron is 0.1-0.5wt%.

9. The method for preparing the 960MPa grade high strength gas shielded solid welding wire according to claim 5, characterized in that: The temperature of the first spheroidizing annealing treatment is 750-770°C, and the time is 10-11 hours; the temperature of the second spheroidizing annealing treatment is 750-770°C, and the time is 10-11 hours.

10. The method for preparing the 960MPa grade high strength gas shielded solid welding wire according to claim 5, characterized in that: The yield strength of the solid welding wire is ≥890MPa, the tensile strength is ≥960MPa, the elongation A is ≥14%, and the impact toughness at -40°C is ≥47J.