Method for improving welding performance of Q420ME wind power steel

Abstract

The invention discloses a welding method for improving the welding performance of Q420ME wind power steel, the thickness of a steel plate is 12-20 mm, firstly, GMAW is adopted for backing welding, and the protective gas is 100% CO2; and then inner and outer side double-face welding is conducted through SAW, and a welding wire and a submerged-arc welding agent are adopted in the welding process. The preheating temperature of the steel plate before welding is 100-150 DEG C, the inter-pass temperature is controlled to be 100-150 DEG C in the welding process, the steel plate is placed in a heating furnace at the temperature of 200-250 DEG C after welding, heat preservation is conducted for 1 h, the steel plate is taken out after heat preservation, the surface is covered with asbestos, and then air cooling is conducted to the According to the method, the welding seam quality is good, the flaw detection qualification rate is 100%, and the welding performance is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power steel, and particularly relates to a method for improving the welding performance of Q420ME wind power steel. Background Art

[0002] Wind power steel is an important material in the construction of wind power generation equipment. Q420ME is mainly used to manufacture wind power tower barrels and other key components. As the main material of the wind turbine tower barrel, it is required to have high strength, high toughness and strong durability. Since the wind turbine tower barrel is formed by welding, the welding performance of wind power steel has become the focus of attention. Not only must the safety and reliability of the welded structure be ensured, but also the comprehensive welding performance must meet the design requirements in order to withstand the huge load and vibration of the wind turbine and ensure the stable operation of the wind turbine. Therefore, it is of great significance to improve the welding performance of Q420ME wind power steel.

[0003] Patent CN 119216727 A discloses a welding method for high-strength steel of wind power tower barrels. This welding method proposes welding steps: S1, welding groove design and preparation; S2, preparation before welding; S3, welding process; S4, post-weld treatment and inspection, but the process parameters of each step implementation process are not proposed in the invention content and specific embodiments. The literature "Research on the Welding Process of Q420NE Steel for the Door Frame of Wind Power Tower Barrels" analyzes the flux-cored wire CO2 gas shielded welding (FCAW) process of the butt joint of Q420NE thick plate for the door frame of wind power tower barrels, and completes the welding process qualification of Q420NE thick plate. The welding process adopted in this literature is different from the welding method adopted in this patent. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for improving the welding performance of Q420ME wind power steel, and to improve the weld quality and performance.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for improving the welding performance of Q420ME wind power steel according to the present invention, the main process parameters:

[0007] The welding plate groove form is X-shaped, double-sided welding is adopted, and the steel plate is preheated to 100-150 °C by flame heating before welding.

[0008] (1) GMAW root pass welding: The wire standard is GB / T8110, the brand is CHW-50CT, the diameter is φ1.2mm, and the shielding gas is 100% CO 2, the flow rate is 15 - 25 L / min, the current is 260 - 300 A, the voltage is 28 - 32 V, the welding speed is 28 - 33 cm / min, the nozzle diameter is 12 - 20 mm, the distance from the contact tip to the workpiece is 15 - 25 mm, the number of welding passes is one pass, and after welding, it is polished with a grinder;

[0009] (2) Double-sided SAW welding on the inner and outer sides: During the welding process, welding wire and submerged arc welding flux are used. The welding wire standard is GB / T5293, the grade is CHW - S3A, and the diameter is φ4.0 mm; the welding flux standard is GB / T5293, the grade is CHF102, the size is 10 - 60 mesh, and the welding flux is pre - dried in an oven at 350 °C for 2 hours and then kept warm at 150 °C. The current is 550 - 650 A, the voltage is 28 - 32 V, the welding speed is 38 - 45 cm / min; the distance from the contact tip to the workpiece is 35 - 40 mm, the number of welding passes is double - sided multi - pass welding, the inter - pass temperature is 100 - 150 °C, and the inter - pass cleaning is done by grinding with a grinder; the weld width is 12 - 16 mm, and the reinforcement on both the front and back sides is 0.8 - 1.2 mm;

[0010] (3) Post - weld heat treatment: After welding, it is placed in a heating furnace at a temperature of 200 - 250 °C and kept warm for 1 h. After taking it out, the surface is covered with asbestos, and then it is air - cooled to room temperature.

[0011] Furthermore, it also includes: (4) Non - destructive testing: 48 h after welding, non - destructive testing is carried out on the weld and the heat - affected zone. The testing equipment is an ultrasonic flaw detector, the K - value of the probe is 2.48 / 1.5, the front - edge of the probe is 9 / 11 mm, the probe frequency is 5 / 2.5 MHz, the testing method is the transverse - wave direct - contact method, the testing standard is NB / T47013.3 - 2015, and the testing ratio is 100%. According to the testing standard, ultrasonic testing is carried out on the weld and the heat - affected zone, and there are no crack and porosity defects, and the testing results meet the requirements of Grade I of the NB / T47013.3 - 2015 standard.

[0012] Furthermore, it also includes: (5) Performance testing: After non - destructive testing, sampling and inspection are carried out on the tensile, impact, bending, and hardness properties of the welded joint. All meet the requirements. The weld has good strength and toughness. The tensile strength of the weld is > 600 MPa, the impact energy at - 40 °C is > 100 J, and no cracks are generated in the bending specimen.

[0013] Furthermore, Q420ME wind power steel plates with a thickness of 12 - 20 mm are used.

[0014] Further, the chemical composition of the steel plate by weight percentage is C: 0.07 - 0.10%, Si: 0.20 - 0.40%, Mn: 1.40 - 1.70%, P: ≤0.015%, S: ≤0.005%, Nb: 0.030 - 0.050%, V: 0.030 - 0.050%, Ti: 0.010 - 0.020%, and the balance is Fe and inevitable impurities.

[0015] Further, the yield strength of the steel plate is 490 - 520 MPa, the tensile strength is 550 - 580 MPa, and the elongation is 24% - 27%.

[0016] Further, the thickness of the steel plate is 12 mm. Before welding, the steel plate is preheated to 100°C by flame heating. First, the GMAW welding method is used for backing welding. The wire standard is GB / T8110, the grade is CHW - 50CT, the diameter is φ1.2 mm, the shielding gas is 100% CO 2 , the flow rate is 20 L / min, the current is 290 A, the voltage is 30 V, the welding speed is 31 cm / min, the nozzle diameter is 15 mm, the distance from the contact tip to the workpiece is 20 mm, the number of welding passes is one pass, and after welding, it is polished with a grinder; then the SAW welding method is used for double-sided welding on the inner and outer sides. During the welding process, a wire and submerged arc welding flux are used. The wire standard is GB / T5293, the grade is CHW - S3A, the diameter is φ4.0 mm; the flux standard is GB / T5293, the grade is CHF102, the size is 10 - 60 mesh, and the flux is pre-dried in an oven at 350°C for 2 hours and then kept warm at 150°C; two passes of welding are carried out on each of the inner and outer sides, the welding current is 560 A, the voltage is 30 V, the welding speed is 40 cm / min; the distance from the contact tip to the workpiece is 35 mm, the interpass temperature is 110°C, and the interpass cleaning is carried out by polishing with a grinder; the weld width is 12 mm, and the reinforcement on both the front and back sides is 1.0 mm; after welding, it is placed in a heating furnace at 200°C for heat preservation for 1 h, taken out after heat preservation, covered with asbestos on the surface, and air-cooled to room temperature; non-destructive testing is carried out on the weld and the heat-affected zone 48 h after welding. The testing equipment is an ultrasonic flaw detector, the K value of the probe is 2.48 / 1.5, the front edge of the probe is 9 / 11 mm, the probe frequency is 5 / 2.5 MHz, the testing method is the transverse wave direct contact method, the testing standard is NB / T47013.3 - 2015, the testing ratio is 100%, and there are no crack and porosity defects; after non-destructive testing, sampling and inspection are carried out on the tensile, impact, bending, and hardness properties of the welded joint, and all meet the requirements.

[0017] Further, the thickness of the steel plate is 15 mm. Before welding, the steel plate is preheated to 120°C by flame heating. First, the GMAW welding method is used for backing welding. The wire standard is GB / T8110, the grade is CHW - 50CT, the diameter is φ1.2 mm, the shielding gas is 100% CO2 , flow rate is 16L / min, current is 260A, voltage is 28V, welding speed is 28cm / min, nozzle diameter is 12mm, distance from conductive nozzle to workpiece is 15mm, welding pass is one, polishing machine is used after welding; then SAW welding method is used for inner and outer double-sided welding, welding wire and submerged arc welding flux are used in the welding process, welding wire standard is GB / T5293, brand is CHW-S3A, diameter is φ4.0mm; welding flux standard is GB / T5293, brand is CHF102, size is 10-60 mesh, welding flux is dried in oven at 350℃ for 2 hours in advance and then kept warm at 150℃; two passes are welded on the inside and three passes are welded on the outside, welding current is 600A, voltage is 28V, welding speed is 42cm / min; conductive nozzle to workpiece The distance is 38mm, the interpass temperature is 120℃, and the interpass cleaning is done by grinding with a grinder; the weld width is 14mm, and the excess heights on the front and back are 0.9mm and 1.1mm respectively; after welding, it is placed in a heating furnace at 220℃ for 1h, and then taken out and the surface is covered with asbestos, and air-cooled to room temperature; 48h after welding, the weld and heat-affected zone are subjected to non-destructive testing. The testing equipment is an ultrasonic flaw detector, the probe K value is 2.48 / 1.5, the probe front edge is 9 / 11mm, the probe frequency is 5 / 2.5MHz, the testing method is the shear wave direct contact method, the testing standard is NB / T47013.3-2015, the testing ratio is 100%, and there are no cracks or pore defects; after non-destructive testing, the tensile, impact, bending and hardness properties of the welded joints are sampled and tested, and all meet the requirements.

[0018] Furthermore, the thickness of the steel plate is 20 mm, and the steel plate is preheated to 150°C by flame heating before welding; first, the GMAW welding method is used for base welding, the welding wire standard is GB / T8110, the brand is CHW-50CT, the diameter is φ1.2 mm, and the shielding gas is 100% CO 2, the flow rate is 25 L / min, the current is 300 A, the voltage is 32 V, the welding speed is 33 cm / min, the nozzle diameter is 20 mm, the distance from the contact tip to the workpiece is 25 mm, the number of welding passes is one, and after welding, it is polished with a grinder; then the double-sided welding of the inner and outer sides is carried out by the SAW welding method. During the welding process, welding wire and submerged arc welding flux are used. The standard of the welding wire is GB / T5293, the grade is CHW-S3A, and the diameter is φ4.0 mm; the standard of the welding flux is GB / T5293, the grade is CHF102, the size is 10 - 60 mesh, and the welding flux is pre-dried in an oven at 350 °C for 2 hours and then kept warm at 150 °C; two passes are welded on the inner side and three passes are welded on the outer side. The welding current is 650 A, the voltage is 32 V, and the welding speed is 45 cm / min; the distance from the contact tip to the workpiece is 40 mm, the inter-pass temperature is 140 °C, and the inter-pass cleaning is carried out by grinding with a grinder; the weld width is 16 mm, and the reinforcement on the front and back sides is 1.1 mm and 1.2 mm respectively; after welding, it is placed in a heating furnace at 250 °C for heat preservation for 1 h, taken out after heat preservation, covered with asbestos on the surface, and air-cooled to room temperature; non-destructive testing is carried out on the weld and the heat-affected zone 48 h after welding. The testing equipment is an ultrasonic flaw detector, the K value of the probe is 2.48 / 1.5, the front edge of the probe is 9 / 11 mm, the probe frequency is 5 / 2.5 MHz, the testing method is the transverse wave direct contact method, the testing standard is NB / T47013.3 - 2015, the testing ratio is 100%, and there are no crack and porosity defects; after non-destructive testing, sampling and inspection are carried out on the tensile, impact, bending, and hardness properties of the welded joint, and all meet the requirements.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are:

[0020] (1) By combining two welding methods of GMAW (CO₂ gas shielded arc welding) and SAW (submerged arc automatic welding), the stability of the weld is ensured, the whole welding process is protected, there are no defects such as oxidation and porosity in the weld, the weld quality is good, and the weld performance is greatly improved.

[0021] (2) After post-weld heat treatment, it is covered with asbestos until it is cooled to room temperature, thereby reducing the surface cooling rate, preventing cracks from being generated due to too fast cooling rate, and thus ensuring a 100% flaw detection qualification rate. At the same time, the difference in the cooling rate between the surface and the core can be reduced, making the surface and core structures consistent and improving the performance stability. Description of the Drawings

[0022] The present invention will be further described below in conjunction with the description of the drawings.

[0023] Figure 1 It is the welded joint and welding sequence of 20 mm thick Q420ME wind power steel plate of the present invention. Specific Embodiments

[0024] The present invention will be further described in detail below in conjunction with specific embodiments.

[0025] Example 1: The thickness of the steel plate is 12 mm. Before welding, the steel plate is preheated to 100 °C by flame heating. First, the root pass welding is carried out by the GMAW welding method. The standard of the welding wire is GB / T8110, the brand is CHW-50CT, the diameter is φ1.2 mm, the shielding gas is 100% CO 2 , the flow rate is 20 L / min, the current is 290 A, the voltage is 30 V, the welding speed is 31 cm / min, the nozzle diameter is 15 mm, the distance from the contact tip to the workpiece is 20 mm, the number of welding passes is one pass, and after welding, it is polished with a grinder. Then, the SAW welding method is used for double-sided welding on the inner and outer sides. During the welding process, welding wire and submerged arc welding flux are used. The standard of the welding wire is GB / T5293, the brand is CHW-S3A, the diameter is φ4.0 mm; the standard of the welding flux is GB / T5293, the brand is CHF102, the size is 10 - 60 mesh, and the welding flux is pre-dried in an oven at 350 °C for 2 hours and then kept warm at 150 °C. Two passes are welded on each of the inner and outer sides. The welding current is 560 A, the voltage is 30 V, and the welding speed is 40 cm / min. The distance from the contact tip to the workpiece is 35 mm, the interpass temperature is 110 °C, and the interpass cleaning is carried out by grinding with a grinder. The weld width is 12 mm, and the reinforcement on both the front and back sides is 1.0 mm. After welding, it is placed in a heating furnace at 200 °C for heat preservation for 1 h. After heat preservation, it is taken out and covered with asbestos on the surface, and air-cooled to room temperature. Non-destructive testing is carried out on the weld and the heat-affected zone 48 h after welding. The testing equipment is an ultrasonic flaw detector. The K value of the probe is 2.48 / 1.5, the front edge of the probe is 9 / 11 mm, the probe frequency is 5 / 2.5 MHz, the testing method is the transverse wave direct contact method, the testing standard is NB / T47013.3 - 2015, the testing ratio is 100%, and there are no defects such as cracks and pores. After non-destructive testing, sampling and inspection are carried out on the tensile, impact, bending, and hardness properties of the welded joint, and all meet the requirements.

[0026] Example 2: The thickness of the steel plate is 15 mm. Before welding, the steel plate is preheated to 120 °C by flame heating. First, the root pass welding is carried out by the GMAW welding method. The standard of the welding wire is GB / T8110, the brand is CHW-50CT, the diameter is φ1.2 mm, the shielding gas is 100% CO 2, the flow rate is 16 L / min, the current is 260 A, the voltage is 28 V, the welding speed is 28 cm / min, the nozzle diameter is 12 mm, the distance from the contact tip to the workpiece is 15 mm, the number of welding passes is one, and after welding, it is polished with a grinder. Then, the double-sided welding of the inner and outer sides is carried out by the SAW welding method. During the welding process, welding wire and submerged arc welding flux are used. The standard of the welding wire is GB / T5293, the brand is CHW-S3A, and the diameter is φ4.0 mm; the standard of the welding flux is GB / T5293, the brand is CHF102, the size is 10 - 60 mesh, and the welding flux is pre-dried in an oven at 350 °C for 2 hours and then kept warm at 150 °C. Two passes are welded on the inner side and three passes are welded on the outer side. The welding current is 600 A, the voltage is 28 V, and the welding speed is 42 cm / min. The distance from the contact tip to the workpiece is 38 mm, the inter-pass temperature is 120 °C, and the inter-pass cleaning is carried out by grinding with a grinder. The weld width is 14 mm, and the reinforcement on the front and back sides is 0.9 mm and 1.1 mm respectively. After welding, it is placed in a heating furnace at 220 °C for heat preservation for 1 h. After heat preservation, it is taken out and the surface is covered with asbestos, and air-cooled to room temperature. Non-destructive testing is carried out on the weld and the heat-affected zone 48 h after welding. The testing equipment is an ultrasonic flaw detector, the K value of the probe is 2.48 / 1.5, the front edge of the probe is 9 / 11 mm, the probe frequency is 5 / 2.5 MHz, the testing method is the transverse wave direct contact method, the testing standard is NB / T47013.3 - 2015, the testing ratio is 100%, and there are no defects such as cracks and pores. After non-destructive testing, sampling and inspection are carried out on the tensile, impact, bending, and hardness properties of the welded joint, and all meet the requirements.

[0027] Example 3: The thickness of the steel plate is 20 mm. Before welding, the steel plate is preheated to 150 °C by flame heating. First, the root pass welding is carried out by the GMAW welding method. The standard of the welding wire is GB / T8110, the brand is CHW-50CT, and the diameter is φ1.2 mm. The shielding gas is 100% CO 2, the flow rate is 25 L / min, the current is 300 A, the voltage is 32 V, the welding speed is 33 cm / min, the nozzle diameter is 20 mm, the distance from the contact tip to the workpiece is 25 mm, the number of welding passes is one pass, and after welding, it is polished with a grinder. Then, the SAW welding method is used for double-sided welding on the inner and outer sides. During the welding process, welding wire and submerged arc welding flux are used. The welding wire standard is GB / T5293, the grade is CHW-S3A, and the diameter is φ4.0 mm; the welding flux standard is GB / T5293, the grade is CHF102, the size is 10 - 60 mesh, and the welding flux is pre-dried in an oven at 350 °C for 2 hours and then kept warm at 150 °C. Two passes are welded on the inner side and three passes are welded on the outer side. The welding current is 650 A, the voltage is 32 V, and the welding speed is 45 cm / min. The distance from the contact tip to the workpiece is 40 mm, the interpass temperature is 140 °C, and the interpass cleaning is carried out by grinding with a grinder. The weld width is 16 mm, and the reinforcement on the front and back sides is 1.1 mm and 1.2 mm respectively. After welding, it is placed in a heating furnace at 250 °C for heat preservation for 1 h. After heat preservation, it is taken out and the surface is covered with asbestos, and then air-cooled to room temperature. Non-destructive testing is carried out on the weld and the heat-affected zone 48 h after welding. The testing equipment is an ultrasonic flaw detector, the K value of the probe is 2.48 / 1.5, the front edge of the probe is 9 / 11 mm, the probe frequency is 5 / 2.5 MHz, the testing method is the transverse wave direct contact method, the testing standard is NB / T47013.3 - 2015, the testing ratio is 100%, and there are no defects such as cracks and pores. After non-destructive testing, sampling and inspection are carried out on the tensile, impact, bending, and hardness properties of the welded joint, and all meet the requirements.

[0028] In Examples 1 - 3, the Q420ME welding plates have the chemical compositions as shown in Table 1, and the properties of the welded joints are shown in Table 2.

[0029] Chemical Compositions (%) of the Format Example in Table 1

[0030] Chemical composition C Si Mn P S Nb V Ti Example 1 0.07 0.22 1.42 0.010 0.002 0.035 0.040 0.012 Example 2 0.09 0.30 1.55 0.011 0.002 0.042 0.035 0.016 Example 3 0.10 0.40 1.68 0.010 0.003 0.048 0.045 0.018

[0031] Welded Joint Properties of Each Example in Table 2

[0032]

[0033] The above-described examples are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for improving the welding performance of Q420ME wind power steel, characterized in that: Main process parameters: The weld plate groove is X-shaped, double-sided welding is adopted, and the steel plate is preheated to 100-150℃ by flame heating before welding. (1) GMAW backing welding: The welding wire standard is GB / T8110, the brand is CHW-50CT, the diameter is φ1.2mm, the shielding gas is 100% CO2, the flow rate is 15-25L / min, the current is 260-300A, the voltage is 28-32V, the welding speed is 28-33cm / min, the nozzle diameter is 12-20mm, the distance from the conductive nozzle to the workpiece is 15-25mm, the welding pass is one pass, and the polishing machine is used for grinding after welding; (2) SAW inside and outside double-sided welding: The welding process uses welding wire and submerged arc welding flux. The welding wire standard is GB / T5293, the brand is CHW-S3A, and the diameter is φ4.0mm; the welding flux standard is GB / T5293, the brand is CHF102, and the size is 10-60 mesh. The welding flux is dried in an oven at 350℃ for 2 hours and then kept at 150℃. The current is 550-650A, the voltage is 28-32V, and the welding speed is 38-45cm / min; the distance from the conductive nozzle to the workpiece is 35-40mm, the welding pass is double-sided multi-pass welding, the temperature between passes is 100-150℃, and the cleaning between passes is done by a grinder; the weld width is 12-16mm, and the front and back excess height is 0.8-1.2mm; (3) Post-weld heat treatment: After welding, place it in a heating furnace at a temperature of 200-250℃ and keep it warm for 1 hour. After keeping warm, take it out and cover the surface with asbestos, and then air cool it to room temperature.

2. The method for improving the welding performance of Q420ME wind power steel according to claim 1, characterized in that: Also includes: (4) Nondestructive testing: 48 hours after welding, the weld and heat-affected zone were subjected to nondestructive testing. The testing equipment was an ultrasonic flaw detector with a probe K value of 2.48 / 1.5, a probe front edge of 9 / 11 mm, a probe frequency of 5 / 2.5 MHz, a shear wave direct contact method, and a testing standard of NB / T47013.3-2015. The testing ratio was 100%. According to the testing standard, ultrasonic testing was performed on the weld and heat-affected zone. No cracks or pores were found. The test results met the requirements of Level I of NB / T47013.3-2015.

3. The method for improving the welding performance of Q420ME wind power steel according to claim 2, characterized in that: Also includes: (5) Performance testing: After non-destructive testing, the tensile, impact, bending and hardness properties of the welded joints were sampled and tested, and all met the requirements. The weld had good strength and toughness, the weld tensile strength was greater than 600MPa, the impact energy at -40℃ was greater than 100J, and no cracks were produced in the bending specimens.

4. The method for improving the welding performance of Q420ME wind power steel according to claim 1, characterized in that: 12-20mm thick Q420ME wind power steel plate is used.

5. The method for improving the welding performance of Q420ME wind power steel according to claim 1 or 4, characterized in that: The chemical composition of the steel plate is C: 0.07-0.10%, Si: 0.20-0.40%, Mn: 1.40-1.70%, P: ≤0.015%, S: ≤0.005%, Nb: 0.030-0.050%, V: 0.030-0.050%, Ti: 0.010-0.020%, and the balance is Fe and unavoidable impurities.

6. The method for improving the welding performance of Q420ME wind power steel according to claim 5, characterized in that: The steel plate has a yield strength of 490-520MPa, a tensile strength of 550-580MPa, and an elongation of 24%-27%.

7. The method for improving the welding performance of Q420ME wind power steel according to claim 1, characterized in that: The thickness of the steel plate is 12mm. The steel plate is preheated to 100℃ by flame heating before welding. First, the GMAW welding method is used for base welding. The welding wire standard is GB / T8110, the brand is CHW-50CT, the diameter is φ1.2mm, the shielding gas is 100% CO2, the flow rate is 20L / min, the current is 290A, the voltage is 30V, the welding speed is 31cm / min, the nozzle diameter is 15mm, the distance from the conductive nozzle to the workpiece is 20mm, the welding pass is one pass, and the polishing machine is used after welding; then the SAW welding method is used for inner and outer double-sided welding. The welding process uses welding wire and submerged arc welding flux. The welding wire standard is GB / T5293, the brand is CHW-S3A, and the diameter is φ4.0mm; the welding flux standard is GB / T5293, the brand is CHF102, the size is 10-60 mesh, and the welding flux is dried in an oven at 350℃ for 2 hours in advance and then kept at 150℃ temperature; two passes each on the inside and outside, the welding current is 560A, the voltage is 30V, and the welding speed is 40cm / min; the distance from the conductive nozzle to the workpiece is 35mm, the temperature between passes is 110℃, and the interpass cleaning is done by a grinder; the weld width is 12mm, and the excess height on the front and back sides is 1.0mm; after welding, it is placed in a heating furnace with a temperature of 200℃ for 1h, and then taken out and covered with asbestos, and air-cooled to room temperature; 48h after welding, the weld and heat-affected zone are subjected to non-destructive testing, and the testing equipment is an ultrasonic flaw detector, the probe K value is 2.48 / 1.5, the probe front is 9 / 11mm, the probe frequency is 5 / 2.5MHz, the testing method is the shear wave direct contact method, the testing standard is NB / T47013.3-2015, the testing ratio is 100%, and there are no cracks or pore defects; after non-destructive testing, the tensile, impact, bending and hardness properties of the welded joints are sampled and tested, and all meet the requirements.

8. The method for improving the welding performance of Q420ME wind power steel according to claim 1, characterized in that: The thickness of the steel plate is 15mm. The steel plate is preheated to 120℃ by flame heating before welding. First, the GMAW welding method is used for base welding. The welding wire standard is GB / T8110, the brand is CHW-50CT, the diameter is φ1.2mm, the shielding gas is 100% CO2, the flow rate is 16L / min, the current is 260A, the voltage is 28V, the welding speed is 28cm / min, the nozzle diameter is 12mm, and the distance from the conductive nozzle to the workpiece is 15mm, one pass for welding, polished by a grinder after welding; then SAW welding method is used for double-sided welding of inside and outside, welding wire and submerged arc welding flux are used in the welding process, the welding wire standard is GB / T5293, the brand is CHW-S3A, the diameter is φ4.0mm; the welding flux standard is GB / T5293, the brand is CHF102, the size is 10-60 mesh, the welding flux is dried in an oven at 350℃ for 2 hours in advance and then kept at 150℃; the inner welding Two passes, three passes on the outside, the welding current is 600A, the voltage is 28V, and the welding speed is 42cm / min; the distance from the conductive nozzle to the workpiece is 38mm, the temperature between passes is 120℃, and the inter-pass cleaning is done by a grinder; the weld width is 14mm, and the excess heights on the front and back are 0.9mm and 1.1mm respectively; after welding, it is placed in a heating furnace at a temperature of 220℃ for 1h, and then taken out and covered with asbestos, and air-cooled to room temperature; 48h after welding, the weld and heat-affected zone are subjected to non-destructive testing, and the testing equipment is an ultrasonic flaw detector, the probe K value is 2.48 / 1.5, the probe front edge is 9 / 11mm, the probe frequency is 5 / 2.5MHz, the testing method is the shear wave direct contact method, the testing standard is NB / T47013.3-2015, the testing ratio is 100%, and there are no cracks or pore defects; after non-destructive testing, the tensile, impact, bending and hardness properties of the welded joints are sampled and tested, and all meet the requirements.

9. The method for improving the welding performance of Q420ME wind power steel according to claim 1, characterized in that: The thickness of the steel plate is 20mm. The steel plate is preheated to 150℃ by flame heating before welding. First, the GMAW welding method is used for base welding. The welding wire standard is GB / T8110, the brand is CHW-50CT, the diameter is φ1.2mm, the shielding gas is 100% CO2, the flow rate is 25L / min, the current is 300A, the voltage is 32V, the welding speed is 33cm / min, the nozzle diameter is 20mm, and the distance from the conductive nozzle to the workpiece is 25mm, one pass for welding, polished by a grinder after welding; then SAW welding method is used for double-sided welding of inside and outside, welding wire and submerged arc welding flux are used in the welding process, the welding wire standard is GB / T5293, the brand is CHW-S3A, the diameter is φ4.0mm; the welding flux standard is GB / T5293, the brand is CHF102, the size is 10-60 mesh, the welding flux is dried in an oven at 350℃ for 2 hours in advance and then kept at 150℃; the inner welding Two passes, three passes on the outside, welding current is 650A, voltage is 32V, welding speed is 45cm / min; the distance from the conductive nozzle to the workpiece is 40mm, the temperature between passes is 140℃, and the interpass cleaning is done by polishing machine; the weld width is 16mm, and the excess heights on the front and back sides are 1.1mm and 1.2mm respectively; after welding, it is placed in a heating furnace at a temperature of 250℃ for 1h, and then taken out and covered with asbestos, and air-cooled to room temperature; 48h after welding, non-destructive testing is carried out on the weld and heat-affected zone, and the testing equipment is an ultrasonic flaw detector, the probe K value is 2.48 / 1.5, the probe front edge is 9 / 11mm, the probe frequency is 5 / 2.5MHz, the testing method is shear wave direct contact method, the testing standard is NB / T47013.3-2015, the testing ratio is 100%, and there are no cracks or pore defects; after non-destructive testing, the tensile, impact, bending and hardness properties of the welded joints are sampled and tested, and all meet the requirements.

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