High-strength steel large thick plate butt joint crack-free efficient welding method

Abstract

The invention relates to the technical field of welding, in particular to a crack-free efficient welding method for a butt joint of a large and thick high-strength steel plate, which comprises the following steps: firstly, forming a welding groove of the large and thick high-strength steel plate into an inverted trapezoidal structure at the upper part and a large truncated edge structure at the lower part; a base plate and an electric heating plate are arranged on the back face of the butt joint gap of the high-strength steel large thick plate; then, the pre-welding assembly gap of the high-strength steel large thick plate is set, and positioned welding is conducted on the four corners of the butt joint gap; then backing welding is conducted on the large truncated edge structure area of the high-strength steel large thick plate; and finally, filling welding and cosmetic welding are carried out on the inverted trapezoidal structure area of the high-strength steel large thick plate, a new welding method is adopted by optimizing the groove form, the welding line cladding metal filling amount is reduced, the welding efficiency is improved, the welding heat input is reduced, welding angle deformation is reduced, and the welding quality is improved through the groove of the inverted trapezoidal large truncated edge, laser welding bottoming and laser wire filling welding filling. And after-welding slow cooling is achieved, the welding pass can be obviously reduced, the welding efficiency is improved, the joint strength is improved, and the welding quality is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a crack-free and efficient welding method for a butt joint of a high-strength steel thick plate. Background Art

[0002] The application of high-strength steel thick plates in oil pipelines, ships, heavy machinery and pressure vessel industries is increasing, and the plate thickness can reach 40 to 80 mm. Traditional welding technologies are mainly based on MAG welding, submerged arc welding and manual welding. When these welding methods are used in the welding of high-strength steel thick plates, there are problems such as large amount of welded metal at the welding groove, many welding passes, low welding efficiency, poor welding process stability, large welding heat input, serious welding angle deformation, joint microstructure deterioration and thermal crack defects. Summary of the invention

[0003] In view of the above problems, the present invention provides a crack-free and efficient welding method for butt joints of high-strength steel thick plates.

[0004] The technical solution adopted is a crack-free and efficient welding method for butt joints of high-strength steel thick plates, comprising the following steps: S1. The welding groove of the high-strength steel thick plate is opened to have an inverted trapezoidal structure at the top and a large blunt edge structure at the bottom; S2. Clean the welding groove; S3. Install a backing plate and an electric heating plate on the back of the butt joint gap of high-strength steel thick plates; S4. Set the gap before welding the high-strength steel thick plate, and perform positioning welding at the four corners of the gap; S5. Perform base welding on the blunt edge structure area of ​​high-strength steel thick plates; S6. Perform filling welding and cap welding in the inverted trapezoidal structure area of ​​high-strength steel thick plates.

[0005] Optionally, in S1, the upper width of the inverted trapezoidal structure is 8 to 10 mm, the lower width is 4 to 5 mm, and the large blunt edge structure ranges from 8 to 14 mm.

[0006] Optionally, in S2, laser cleaning is adopted, and the laser cleaning mode is pulsed laser, with a wavelength of 1060nm, a laser power of 30W, a pulse width of 5ns, a frequency of 600Hz, and a scanning rate of 6000mm / s.

[0007] Optionally, in S3, the pad is arranged between the electric heating plate and the large blunt edge structure, and the pad thickness is greater than 2 mm.

[0008] Optionally, in S3, the material and composition of the pad are the same as those of the high-strength steel thick plate.

[0009] Optionally, in S3, the electric heating plate preheats the positioning weld and slowly cools the filling weld. During preheating, the predetermined temperature is 100°C to 200°C. The electric heating plate adopts resistance heating, and the temperature is first set to 10°C higher than the predetermined temperature. After the temperature of the high-strength steel thick plate reaches the predetermined temperature, the temperature of the electric heating plate is adjusted to the predetermined temperature.

[0010] Optionally, in S4, the pre-welding gap of high-strength steel thick plates is set to 0-0.2 mm.

[0011] Optionally, in S5, the base welding adopts high-power single laser welding, the laser power is 6kW~8kW, the defocus amount is 0, the welding speed is 70~80cm / min, the shielding gas is 99.99% argon gas, and the gas flow rate is 15~25L / min.

[0012] Optionally, in S6, the filling weld and the cap weld are made by laser wire welding, with a laser power of 3.8 to 4.5 kW, a defocusing amount of 12 to 18 mm, a welding speed of 30 to 40 cm / min, and a wire feeding speed of 3.8 to 4.8 m / min through the welding gun wire feeding nozzle, and the welding wire is solid or flux-cored with a diameter of 1.2 mm.

[0013] Optionally, in S6, a protrusion is provided at the end of the wire feeding nozzle of the welding gun, and the protrusion has a length of 100 mm, an outer diameter of 4 mm, and an inner diameter of 1.5 mm. The beneficial effects of the present invention are: On the one hand, by optimizing the groove form and adopting a new welding method, the amount of weld cladding metal filling is reduced, the welding efficiency is improved, the welding heat input is reduced, the welding angle deformation is reduced, the weld microstructure is optimized, and the strength of the weld joint is improved.

[0014] On the other hand, the inverted trapezoidal groove with large blunt edges, laser welding primer and laser wire welding filling, as well as slow cooling after welding, can significantly reduce the number of welding passes, improve welding efficiency, reduce welding deformation, refine the weld grain and thermal cracks in the weld area, improve joint strength, and ensure welding quality. It can effectively solve the technical problems of many passes, large deformation, and poor organization in traditional welding of high-strength steel thick plate butt joints. It is simple to operate and has strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram showing the shape and size of the welding gun wire feeding nozzle; Figure 2 Schematic diagram of welding inverted trapezoidal groove.

[0016] The accompanying drawings are marked as follows: 1 is a protruding portion, 2 is a welding gun wire feeding nozzle, 3 is a high-strength steel thick plate, 4 is an inverted trapezoidal structure, 5 is a backing plate, 6 is a large blunt edge structure, and 7 is an electric heating plate. DETAILED DESCRIPTION

[0017] The following describes the implementation of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0018] It should be noted that the illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0019] Example 1 like Figure 2 As shown, a crack-free and efficient welding method for a butt joint of a high-strength steel thick plate comprises the following steps: S1. The high-strength steel thick plate 3 is welded with a groove having an upper inverted trapezoidal structure 4 and a large blunt edge structure 6 at the lower portion; S2. Clean the welding groove; S3. A pad 5 and an electric heating plate 7 are provided on the back of the butt gap of a high-strength steel plate 3; S4. Set the gap for the high-strength steel thick plate 3 before welding, and perform positioning welding at the four corners of the gap; S5. Perform base welding in the large blunt edge structure 6 area of ​​the high-strength steel thick plate 3; S6. Perform filling welding and cap welding in the inverted trapezoidal structure 4 area of ​​the high-strength steel thick plate 3.

[0020] The purpose of this design is to reduce the amount of weld metal filling by optimizing the groove form and adopting a new welding method, thereby improving welding efficiency, reducing welding heat input, reducing welding angle deformation, optimizing weld microstructure, and improving weld joint strength. At the same time, the groove with large blunt edges of the inverted trapezoid plus laser welding primer and laser wire welding filling, as well as slow cooling after welding, can significantly reduce the number of welding passes, improve welding efficiency, reduce welding deformation, refine weld grains and thermal cracks in the weld zone, improve joint strength, and ensure welding quality. It can effectively solve the technical problems of many passes, large deformation, and poor microstructure in traditional welding of high-strength steel thick plate butt joints. It is simple to operate and has strong applicability.

[0021] Example 2 like Figure 2As shown, a crack-free and efficient welding method for a butt joint of a high-strength steel thick plate comprises the following steps: S1. The welding groove of the high-strength steel thick plate 3 is opened to an upper inverted trapezoidal structure 4 and a large blunt edge structure 6 at the lower part, wherein the upper width of the inverted trapezoidal structure 4 is 8 to 10 mm, the lower width is 4 to 5 mm, and the large blunt edge structure 6 ranges from 8 to 14 mm; S2. Clean the welding groove; S3. A pad 5 and an electric heating plate 7 are provided on the back of the butt gap of a high-strength steel plate 3; S4. Set the gap for the high-strength steel thick plate 3 before welding, and perform positioning welding at the four corners of the gap; S5. Perform base welding in the large blunt edge structure 6 area of ​​the high-strength steel thick plate 3; S6. Perform filling welding and cap welding in the inverted trapezoidal structure 4 area of ​​the high-strength steel thick plate 3.

[0022] The purpose of this design is to reduce the amount of weld metal filling by optimizing the groove form and adopting a new welding method, thereby improving welding efficiency, reducing welding heat input, reducing welding angle deformation, optimizing weld microstructure, and improving weld joint strength. At the same time, the groove with large blunt edges of the inverted trapezoid plus laser welding primer and laser wire welding filling, as well as slow cooling after welding, can significantly reduce the number of welding passes, improve welding efficiency, reduce welding deformation, refine weld grains and thermal cracks in the weld zone, improve joint strength, and ensure welding quality. It can effectively solve the technical problems of many passes, large deformation, and poor microstructure in traditional welding of high-strength steel thick plate butt joints. It is simple to operate and has strong applicability.

[0023] At the same time, based on Example 1, a specific groove structure and size that can be implemented are provided, and the welding effect is better under this size.

[0024] Example 3 like Figure 2 As shown, a crack-free and efficient welding method for a butt joint of a high-strength steel thick plate comprises the following steps: S1. The welding groove of the high-strength steel thick plate 3 is opened to an upper inverted trapezoidal structure 4 and a large blunt edge structure 6 at the lower part, wherein the upper width of the inverted trapezoidal structure 4 is 8 to 10 mm, the lower width is 4 to 5 mm, and the large blunt edge structure 6 ranges from 8 to 14 mm; S2. Clean the welding groove by laser cleaning, and the laser cleaning mode is pulsed laser, with a wavelength of 1060nm, a laser power of 30W, a pulse width of 5ns, a frequency of 600Hz, and a scanning rate of 6000mm / s; S3. A pad 5 and an electric heating plate 7 are provided on the back of the butt gap of a high-strength steel plate 3; S4. Set the gap for the high-strength steel thick plate 3 before welding, and perform positioning welding at the four corners of the gap; S5. Perform base welding in the large blunt edge structure 6 area of ​​the high-strength steel thick plate 3; S6. Perform filling welding and cap welding in the inverted trapezoidal structure 4 area of ​​the high-strength steel thick plate 3.

[0025] The purpose of this design is to reduce the amount of weld metal filling by optimizing the groove form and adopting a new welding method, thereby improving welding efficiency, reducing welding heat input, reducing welding angle deformation, optimizing weld microstructure, and improving weld joint strength. At the same time, the groove with large blunt edges of the inverted trapezoid plus laser welding primer and laser wire welding filling, as well as slow cooling after welding, can significantly reduce the number of welding passes, improve welding efficiency, reduce welding deformation, refine weld grains and thermal cracks in the weld zone, improve joint strength, and ensure welding quality. It can effectively solve the technical problems of many passes, large deformation, and poor microstructure in traditional welding of high-strength steel thick plate butt joints. It is simple to operate and has strong applicability.

[0026] At the same time, based on Example 2, a laser cleaning parameter for the groove that can be implemented is provided, and the welding effect is better under this parameter.

[0027] Example 4 like Figure 2 As shown, a crack-free and efficient welding method for a butt joint of a high-strength steel thick plate comprises the following steps: S1. The welding groove of the high-strength steel thick plate 3 is opened to an upper inverted trapezoidal structure 4 and a large blunt edge structure 6 at the lower part, wherein the upper width of the inverted trapezoidal structure 4 is 8 to 10 mm, the lower width is 4 to 5 mm, and the large blunt edge structure 6 ranges from 8 to 14 mm; S2. Clean the welding groove by laser cleaning, and the laser cleaning mode is pulsed laser, with a wavelength of 1060nm, a laser power of 30W, a pulse width of 5ns, a frequency of 600Hz, and a scanning rate of 6000mm / s; S3. A backing plate 5 and an electric heating plate 7 are provided on the back of the butt gap of the high-strength steel thick plate 3, and the backing plate 5 is provided between the electric heating plate 7 and the large blunt edge structure 6, and the thickness of the backing plate 5 is greater than 2 mm, and the material and composition of the backing plate 5 are the same as those of the high-strength steel thick plate 3; S4. Set the gap for the high-strength steel thick plate 3 before welding, and perform positioning welding at the four corners of the gap; S5. Perform base welding in the large blunt edge structure 6 area of ​​the high-strength steel thick plate 3; S6. Perform filling welding and cap welding in the inverted trapezoidal structure 4 area of ​​the high-strength steel thick plate 3.

[0028] The purpose of this design is to reduce the amount of weld metal filling by optimizing the groove form and adopting a new welding method, thereby improving welding efficiency, reducing welding heat input, reducing welding angle deformation, optimizing weld microstructure, and improving weld joint strength. At the same time, the groove with large blunt edges of the inverted trapezoid plus laser welding primer and laser wire welding filling, as well as slow cooling after welding, can significantly reduce the number of welding passes, improve welding efficiency, reduce welding deformation, refine weld grains and thermal cracks in the weld zone, improve joint strength, and ensure welding quality. It can effectively solve the technical problems of many passes, large deformation, and poor microstructure in traditional welding of high-strength steel thick plate butt joints. It is simple to operate and has strong applicability.

[0029] At the same time, based on Example 3, a specific parameter of a backing plate is provided. In the specific implementation, the backing plate has a thickness of not less than 2 mm, a width of not less than 40 mm, and a length not less than the length of the welded high-strength steel thick plate. On the one hand, it can prevent the bottom welding from leaking, and on the other hand, it has a good preheating effect during preheating.

[0030] Example 5 like Figure 2 As shown, a crack-free and efficient welding method for a butt joint of a high-strength steel thick plate comprises the following steps: S1. The welding groove of the high-strength steel thick plate 3 is opened to an upper inverted trapezoidal structure 4 and a large blunt edge structure 6 at the lower part, wherein the upper width of the inverted trapezoidal structure 4 is 8 to 10 mm, the lower width is 4 to 5 mm, and the large blunt edge structure 6 ranges from 8 to 14 mm; S2. Clean the welding groove by laser cleaning, and the laser cleaning mode is pulsed laser, with a wavelength of 1060nm, a laser power of 30W, a pulse width of 5ns, a frequency of 600Hz, and a scanning rate of 6000mm / s; S3. A backing plate 5 and an electric heating plate 7 are arranged on the back of the butt joint gap of the high-strength steel thick plate 3, and the backing plate 5 is arranged between the electric heating plate 7 and the large blunt edge structure 6, and the thickness of the backing plate 5 is greater than 2 mm. The material and composition of the backing plate 5 are the same as those of the high-strength steel thick plate 3. The electric heating plate 7 performs welding preheating for positioning welding and slow cooling for filling welding. During preheating, the predetermined temperature is 100°C to 200°C. The electric heating plate 7 adopts resistance heating, and the temperature is first set to 10°C higher than the predetermined temperature. After the temperature of the high-strength steel thick plate 3 reaches the predetermined temperature, the temperature of the electric heating plate 7 is adjusted to the predetermined temperature; S4. Set the gap for the high-strength steel thick plate 3 before welding, and perform positioning welding at the four corners of the gap; S5. Perform base welding in the large blunt edge structure 6 area of ​​the high-strength steel thick plate 3; S6. Perform filling welding and cap welding in the inverted trapezoidal structure 4 area of ​​the high-strength steel thick plate 3.

[0031] The purpose of this design is to reduce the amount of weld metal filling by optimizing the groove form and adopting a new welding method, thereby improving welding efficiency, reducing welding heat input, reducing welding angle deformation, optimizing weld microstructure, and improving weld joint strength. At the same time, the groove with large blunt edges of the inverted trapezoid plus laser welding primer and laser wire welding filling, as well as slow cooling after welding, can significantly reduce the number of welding passes, improve welding efficiency, reduce welding deformation, refine weld grains and thermal cracks in the weld zone, improve joint strength, and ensure welding quality. It can effectively solve the technical problems of many passes, large deformation, and poor microstructure in traditional welding of high-strength steel thick plate butt joints. It is simple to operate and has strong applicability.

[0032] At the same time, based on Example 4, a heating method and heating parameters of an electric heating plate are provided, and the welding effect is better under this parameter.

[0033] Example 6 like Figure 2 As shown, a crack-free and efficient welding method for a butt joint of a high-strength steel thick plate comprises the following steps: S1. The welding groove of the high-strength steel thick plate 3 is opened to an upper inverted trapezoidal structure 4 and a large blunt edge structure 6 at the lower part, wherein the upper width of the inverted trapezoidal structure 4 is 8 to 10 mm, the lower width is 4 to 5 mm, and the large blunt edge structure 6 ranges from 8 to 14 mm; S2. Clean the welding groove by laser cleaning, and the laser cleaning mode is pulsed laser, with a wavelength of 1060nm, a laser power of 30W, a pulse width of 5ns, a frequency of 600Hz, and a scanning rate of 6000mm / s; S3. A backing plate 5 and an electric heating plate 7 are arranged on the back of the butt joint gap of the high-strength steel thick plate 3, and the backing plate 5 is arranged between the electric heating plate 7 and the large blunt edge structure 6, and the thickness of the backing plate 5 is greater than 2 mm. The material and composition of the backing plate 5 are the same as those of the high-strength steel thick plate 3. The electric heating plate 7 performs welding preheating for positioning welding and slow cooling for filling welding. During preheating, the predetermined temperature is 100°C to 200°C. The electric heating plate 7 adopts resistance heating, and the temperature is first set to 10°C higher than the predetermined temperature. After the temperature of the high-strength steel thick plate 3 reaches the predetermined temperature, the temperature of the electric heating plate 7 is adjusted to the predetermined temperature; S4. Set the gap between the high-strength steel thick plate 3 before welding, and perform positioning welding at the four corners of the gap, wherein the gap between the high-strength steel thick plate 3 before welding is set to 0-0.2mm; S5. Perform base welding in the large blunt edge structure 6 area of ​​the high-strength steel thick plate 3, wherein the base welding adopts high-power single laser welding, the laser power is 6kW~8kW, the defocus amount is 0, the welding speed is 70~80cm / min, the shielding gas is 99.99% argon gas, and the gas flow rate is 15~25L / min; S6. Perform filling welding and cap welding in the inverted trapezoidal structure 4 area of ​​the high-strength steel thick plate 3.

[0034] The purpose of this design is to reduce the amount of weld metal filling by optimizing the groove form and adopting a new welding method, thereby improving welding efficiency, reducing welding heat input, reducing welding angle deformation, optimizing weld microstructure, and improving weld joint strength. At the same time, the groove with large blunt edges of the inverted trapezoid plus laser welding primer and laser wire welding filling, as well as slow cooling after welding, can significantly reduce the number of welding passes, improve welding efficiency, reduce welding deformation, refine weld grains and thermal cracks in the weld zone, improve joint strength, and ensure welding quality. It can effectively solve the technical problems of many passes, large deformation, and poor microstructure in traditional welding of high-strength steel thick plate butt joints. It is simple to operate and has strong applicability.

[0035] At the same time, a base welding parameter is provided based on Example 5, and the welding effect is better under this parameter.

[0036] Example 7 like Figure 1 and 2 As shown, a crack-free and efficient welding method for a butt joint of a high-strength steel thick plate comprises the following steps: S1. The welding groove of the high-strength steel thick plate 3 is opened to an upper inverted trapezoidal structure 4 and a large blunt edge structure 6 at the lower part, wherein the upper width of the inverted trapezoidal structure 4 is 8 to 10 mm, the lower width is 4 to 5 mm, and the large blunt edge structure 6 ranges from 8 to 14 mm; S2. Clean the welding groove by laser cleaning, and the laser cleaning mode is pulsed laser, with a wavelength of 1060nm, a laser power of 30W, a pulse width of 5ns, a frequency of 600Hz, and a scanning rate of 6000mm / s; S3. A backing plate 5 and an electric heating plate 7 are arranged on the back of the butt joint gap of the high-strength steel thick plate 3, and the backing plate 5 is arranged between the electric heating plate 7 and the large blunt edge structure 6, and the thickness of the backing plate 5 is greater than 2 mm. The material and composition of the backing plate 5 are the same as those of the high-strength steel thick plate 3. The electric heating plate 7 performs welding preheating for positioning welding and slow cooling for filling welding. During preheating, the predetermined temperature is 100°C to 200°C. The electric heating plate 7 adopts resistance heating, and the temperature is first set to 10°C higher than the predetermined temperature. After the temperature of the high-strength steel thick plate 3 reaches the predetermined temperature, the temperature of the electric heating plate 7 is adjusted to the predetermined temperature; S4. Set the gap between the high-strength steel thick plate 3 before welding, and perform positioning welding at the four corners of the gap, wherein the gap between the high-strength steel thick plate 3 before welding is set to 0-0.2mm; S5. Perform base welding in the large blunt edge structure 6 area of ​​the high-strength steel thick plate 3, wherein the base welding adopts high-power single laser welding, the laser power is 6kW~8kW, the defocus amount is 0, the welding speed is 70~80cm / min, the shielding gas is 99.99% argon gas, and the gas flow rate is 15~25L / min; S6. Filling welding and cap welding are performed in the inverted trapezoidal structure 4 area of ​​the high-strength steel thick plate 3. The filling welding and cap welding adopt laser wire welding with a laser power of 3.8-4.5kW, a defocusing amount of 12-18mm, a welding speed of 30-40cm / min, and a wire feeding speed of 3.8-4.8m / min through the welding gun wire feeding nozzle 2. The welding wire is solid or flux-cored with a diameter of 1.2mm, and a protrusion 1 is provided at the end of the welding gun wire feeding nozzle 2. The length of the protrusion 1 is 100mm, the outer diameter is 4mm, and the inner diameter is 1.5mm.

[0037] The purpose of this design is to reduce the amount of weld metal filling by optimizing the groove form and adopting a new welding method, thereby improving welding efficiency, reducing welding heat input, reducing welding angle deformation, optimizing weld microstructure, and improving weld joint strength. At the same time, the groove with large blunt edges of the inverted trapezoid plus laser welding primer and laser wire welding filling, as well as slow cooling after welding, can significantly reduce the number of welding passes, improve welding efficiency, reduce welding deformation, refine weld grains and thermal cracks in the weld zone, improve joint strength, and ensure welding quality. It can effectively solve the technical problems of many passes, large deformation, and poor microstructure in traditional welding of high-strength steel thick plate butt joints. It is simple to operate and has strong applicability.

[0038] At the same time, based on Example 6, a specific implementation method of the parameters of the filling weld and the cap weld and a matching welding gun wire feeding nozzle are provided, and the welding effect is better under this parameter.

[0039] Example 8 Taking the actual welding of 70mm thick 950MPa grade bainite high-strength steel as an example, the test plate is 100mm wide and 150mm long, including the following steps: S1. The test plate is grooved, the groove form is an inverted trapezoidal groove at the top, and a large blunt edge is left at the bottom. The width of the groove at the top is 8mm, the width at the bottom is 4mm, and the blunt edge size at the bottom is 10mm; S2. The groove before welding is cleaned by laser cleaning technology. The laser mode is pulse laser, the wavelength is 1060nm, the laser power is 30W, the pulse width is 5ns, the frequency is 600Hz, and the scanning rate is 6000mm / s; S3. Assembly before welding, the gap between the groups is 0mm, and MIG welding is used to perform positioning welding at the four corners of the group; S4. Pad, a pad is placed on the back of the test plate gap. The pad is 160 mm long and 200 mm wide. The same steel as the parent material is used as the pad; S5. Preheating before welding: Use a heating plate to preheat the thick plate to be welded before welding, and the preset temperature is 120℃. The heating plate uses resistance heating, and the temperature is first set to 10℃ higher than the preset temperature. After the temperature of the thick plate reaches the preset temperature, the heating plate temperature is adjusted to the preset temperature and kept in the heating state, which plays the role of slow cooling treatment for the weld after welding; S6. Base welding: single laser welding is used for base welding. The laser power is 6.8kW, the defocus is 0, the welding speed is 75cm / min, and the shielding gas is 99.99% argon gas with a gas flow rate of 15L / min. S7. Filling welding and capping welding, filling welding and capping welding adopt laser wire welding, filling layer 1-6 laser power 3.8kw, wire feeding speed 4.0m / min, welding speed 40cm / min; filling layer 7-10 laser power 4.0kw, wire feeding speed 4.3m / min, welding speed 38cm / min; filling layer 11-17 laser power 4.2kw, wire feeding speed 4.5m / min, welding speed 36cm / min; filling layer 18 laser power 4.5kw, wire feeding speed 4.6m / min, welding speed 33cm / min; 6 welding parameters are laser power 3.8-4.5kW, defocus 12-18mm, welding speed 30-40cm / min, wire feeding speed 3.8-4.8, shielding gas adopts 80% argon gas + 20% carbon dioxide mixed gas, gas flow rate is 15L / min; S8. Slow cooling after welding. During the continuous laser wire welding process, the resistance preheating plate is not turned off to achieve the purpose of slow cooling.

[0040] The entire welding process is very stable, the weld is well formed, no porosity defects are found in the weld, no incomplete fusion defects and post-weld thermal crack defects are found on the side wall, and the post-weld angular deformation is 0.

[0041] The welded joints were sampled in layers and the tensile strength was tested as shown in the table below. The tensile strength of each layer of the joint was higher than that of the parent material, and the fusion zone had the highest tensile strength of 1100MPa. The structure of the cover layer was mainly needle-shaped and lamellar bainite, with a small amount of lath martensite. The middle of the filling layer was mainly needle-shaped ferrite, tempered martensite, and bainite. The base layer was coarse columnar crystals, martensite, and bainite. The heat-affected zone of the joint was only 1.2 to 1.5 mm.

[0042] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A crack-free and efficient welding method for high-strength steel thick plate butt joints, characterized in that: The following steps are involved: S1. The welding groove of the high-strength steel thick plate (3) is opened to have an inverted trapezoidal structure (4) at the upper part and a large blunt edge structure (6) at the lower part; S2. Clean the welding groove; S3. A backing plate (5) and an electric heating plate (7) are provided on the back of the butt gap of the high-strength steel thick plate (3); S4. Setting the gap before welding the high-strength steel thick plate (3) and performing tack welding at the four corners of the gap; S5. Performing a base weld in the large blunt edge structure (6) area of ​​the high-strength steel thick plate (3); S6. Perform filling welding and cap welding in the inverted trapezoidal structure (4) area of ​​the high-strength steel thick plate (3).

2. The method for highly efficient crack-free welding of high-strength steel thick plate butt joints according to claim 1 is characterized in that: In S1, the upper width of the inverted trapezoidal structure (4) is 8 to 10 mm, the lower width is 4 to 5 mm, and the large blunt edge structure (6) ranges from 8 to 14 mm.

3. The method for highly efficient crack-free welding of high-strength steel thick plate butt joints according to claim 1 is characterized in that: In S2, laser cleaning is adopted, and the laser cleaning mode is pulsed laser, with a wavelength of 1060nm, a laser power of 30W, a pulse width of 5ns, a frequency of 600Hz, and a scanning rate of 6000mm / s.

4. The method for highly efficient crack-free welding of high-strength steel thick plate butt joints according to claim 1 is characterized in that: In S3, the pad (5) is arranged between the electric heating plate (7) and the large blunt edge structure (6), and the pad (5) has a thickness greater than 2 mm.

5. The method for highly efficient crack-free welding of high-strength steel thick plate butt joints according to claim 1 is characterized in that: In S3, the material and composition of the backing plate (5) are the same as those of the high-strength steel thick plate (3).

6. The method for highly efficient crack-free welding of high-strength steel thick plate butt joints according to claim 1, characterized in that: In S3, the electric heating plate (7) performs welding preheating for the positioning weld and slow cooling for the filling weld. During preheating, the predetermined temperature is 100° C. to 200° C. The electric heating plate (7) uses resistance heating and first sets the temperature to 10° C. higher than the predetermined temperature. After the temperature of the high-strength steel thick plate (3) reaches the predetermined temperature, the temperature of the electric heating plate (7) is adjusted to the predetermined temperature.

7. The method for highly efficient crack-free welding of high-strength steel thick plate butt joints according to claim 1 is characterized in that: In S4, the gap between the high-strength steel thick plates (3) before welding is set to 0-0.2 mm.

8. The method for highly efficient crack-free welding of high-strength steel thick plate butt joints according to claim 1, characterized in that: In S5, the base welding adopts high-power single laser welding, the laser power is 6kW~8kW, the defocus amount is 0, the welding speed is 70~80cm / min, the protective gas is 99.99% argon gas, and the gas flow rate is 15~25L / min.

9. The method for highly efficient crack-free welding of high-strength steel thick plate butt joints according to claim 1, characterized in that: In S6, the filling welding and the cap welding are performed by laser wire welding, with a laser power of 3.8 to 4.5 kW, a defocusing amount of 12 to 18 mm, a welding speed of 30 to 40 cm / min, and a wire feeding speed of 3.8 to 4.8 m / min through the welding gun wire feeding nozzle (2). The welding wire is solid or flux-cored with a diameter of 1.2 mm.

10. A crack-free and efficient welding method for high-strength steel thick plate butt joints according to claim 9, characterized in that: In S6, a protruding portion (1) is provided at the end of the welding gun wire feeding nozzle (2), and the protruding portion (1) has a length of 100 mm, an outer diameter of 4 mm, and an inner diameter of 1.5 mm.

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