Stainless steel composite plate fusion welding process

Abstract

The invention relates to the technical field of welding process application, in particular to a stainless steel composite plate fusion welding process which comprises the following steps: 1, preparation before welding: preparing a stainless steel composite plate and a welding material, and carrying out groove processing; (2) workpiece pretreatment, specifically, finish machining is conducted on a groove interface through machining, and a groove and the two sides of the groove are removed through an angular grinding machine till metallic luster is exposed; 3, a welding machine is prepared and fixed, preset welding control parameters are input into the intelligent control device, the welding position is adjusted, a welding gun moving and height adjusting scheme is generated, and welding operation is conducted; (2) welding an outer transition layer; according to the method, the limitation of a traditional single welding method is broken through, and the welding efficiency and quality are improved through process cooperation; the groove structure is optimized to reduce stress concentration and material consumption; and a whole-process quality control system is established to ensure that the mechanical property and the corrosion resistance of the weld joint reach the standard.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding process, in particular to a melting welding process for stainless steel clad plate. BACKGROUND

[0002] The stainless steel clad plate combines the high strength and low cost of the carbon steel base layer with the corrosion resistance of the stainless steel cladding layer, and is widely used in the fields of chemical industry, pressure vessels, energy, etc. In particular, the stainless steel clad plate 310S+Q245R is used as the core material for manufacturing equipment such as titanium sponge reactors, and the welding of the stainless steel clad plate faces the following industry-wide problems:

[0003] Defects of traditional process: when a single welding method (such as CO2 welding or submerged arc welding) is used, there are problems such as cracking of the welded joint (stress concentration caused by the difference in thermal expansion coefficient between the base layer and the cladding layer), insufficient corrosion resistance (severe dilution of the transition layer alloy), and poor fusion (poor metallurgical compatibility between carbon steel and stainless steel), and the flaw detection qualification rate is generally less than 60%.

[0004] Limitations of groove design: the traditional symmetrical V-shaped groove requires a large amount of stainless steel electrode filling, which is high in cost and has a stress concentration coefficient of more than 0.8, and carbon arc gouging can easily cause carburization of the stainless steel layer, with a one-time weld pass rate of only about 50%.

[0005] Insufficient process compatibility: existing processes cannot balance efficient filling of the base layer and precise control of the cladding layer, such as large heat input of submerged arc welding leading to alloy dilution, and MAG welding causing fine cracks due to alloy burning (which can only be detected by penetration detection).

[0006] There is a lack of mature process specifications in China, especially for the welding parameters and stress regulation of 36mm thick clad plate (6mm stainless steel + 30mm carbon steel), and there is a lack of systematic solutions.

[0007] Therefore, the traditional process requires frequent rework, which is high in production cost (large consumption of stainless steel electrode), and cannot meet the stringent requirements of 18-cycle periods of reduction, distillation, cooling, etc. for equipment such as titanium sponge reactors. SUMMARY

[0008] Technical problems solved

[0009] In view of the above-mentioned shortcomings of the prior art, the present application provides a melting welding process for stainless steel clad plate, which can effectively solve a plurality of problems in the prior art.

[0010] Technical scheme

[0011] The present application provides a melting welding process for stainless steel clad plate, comprising:

[0012] Step 1: ① Pre-welding preparation: Prepare the stainless steel composite plate and welding materials, and perform beveling; ② Workpiece pretreatment: Use machining to finely process the bevel interface, and use an angle grinder to remove the bevel and both sides until the metal luster is exposed; ③ Prepare and fix the welding machine, input the preset welding control parameters into the intelligent control device, adjust the welding position, generate the welding torch movement and height adjustment scheme, and perform the welding operation. Also, pre-prepare the welding materials.

[0013] Step 2: Perform welding according to the welding process sequence: ① Welding of the inner base layer; ② Welding of the outer transition layer; ③ Welding of the outer cladding layer;

[0014] Step 3: Post-weld flaw detection. The flaw detection device includes an ultrasonic generator and an ultrasonic receiver, both of which are fixed to a mounting plate. The welding torch is fixed to the middle of the mounting plate. One side of the mounting plate is fixedly connected to a lifting assembly. A rotating assembly is provided at the bottom of the welding torch. The workpiece is placed at the top of the rotating assembly. Both the rotating assembly and the lifting assembly are fixed to the top of the worktable. A side column is fixed to one side of the top of the worktable. A mounting assembly is fixed to the side column. A CCD camera is fixed to the end of the mounting assembly. The camera lens is equipped with a high-temperature resistant protective cover (temperature resistance ≥200℃) and a variable-focus optical system. The CCD camera is connected to the intelligent control device in the welding machine via Ethernet, supporting an image acquisition rate of 30 frames per second. The intelligent control device has a vision control system and an image recognition algorithm.

[0015] Furthermore, in step 1①, the bevel adopts a double-sided V-shaped asymmetrical bevel with "wider outer side and narrower inner side", and the specific parameters are as follows: the outer cladding material is 310S stainless steel: bevel angle 42°, depth 12mm, blunt edge 2mm, root gap 2mm; the inner base material is Q245R carbon steel: bevel angle 28°, depth 24mm, blunt edge 2mm, root gap 2mm.

[0016] Furthermore, in step 1②, during the finishing process, the surface roughness Ra of the workpiece is ≤12.5μm; the grinding range of oil stains and rust on the bevel and both sides is 200mm; before carbon arc gouging to clean the root, lime solution is applied to 200mm on both sides of the bevel to prevent splashing and adhesion.

[0017] Further, in step 1③, the welding equipment includes: a CO2 welding machine with a current accuracy of ±5A, a gas flow rate of 15-20L / min, and equipped with ER50-6 solid core welding wire; an arc welding machine with a current accuracy of ±3A, suitable for short arc operation of shielded metal arc welding, equipped with A307 stainless steel welding rods for the transition layer and A407 stainless steel welding rods as the cladding material; and welding material pretreatment: the A307 and A407 welding rods need to be dried at 350℃ for 2 hours and placed in a 100-150℃ insulated container for use as needed.

[0018] Furthermore, in step two①, the inner base layer welding adopts CO2 gas shielded welding, and the thickness of each weld layer is controlled at 2-3mm. Straight-line electrode movement or small-amplitude oscillation is used to control the heat input ≤1.5kJ / mm and suppress grain coarsening. After the inner base layer is welded, carbon arc gouging is performed on the root of the outer weld of the cylinder to a depth of 3-4mm. In step two, the outer transition layer welding adopts shielded metal arc welding, with a welding speed of 10-15cm / min. The interpass temperature is ≤150℃, and the weld height is 2-3mm lower than the surface of the base material. In step three, the outer cladding layer welding adopts shielded metal arc welding, with a welding speed of 12-18cm / min. The angle between the electrode and the welding direction is 70°-80°.

[0019] Furthermore, corner brackets are fixed on the side wall of the side column, sliding rods are fixed between the corner brackets, and docking blocks are fixed on the sliding rods. The docking blocks are fixedly connected to the mounting rods in the mounting assembly, and the end of the mounting rods is fixedly connected to the locking block. The locking block is inserted and fixed to the industrial CCD camera.

[0020] Furthermore, the lifting assembly includes a side rod fixed to the side column, a cylinder fixed to the side plate, and a mounting plate fixed to the cylinder output end.

[0021] Furthermore, the rotating assembly includes a base fixed to the top of the worktable, a bottom cylinder fixed to the top of the base, and a drive motor. The output end of the drive motor is connected to the drive gear transmission. The drive gear meshes and is fixed with the driven gear. The middle part of the driven gear is fixedly connected to the rotating rod. The bottom of the rotating rod is sleeved inside the bottom cylinder. The top of the rotating rod is fixedly connected to the processing table. A retaining ring is sleeved on the top of the rotating rod at the bottom of the bottom cylinder. The top of the drive gear is fixedly connected to the top plate, and the rotating rod passes through the top plate.

[0022] Furthermore, the workpiece includes a carbon steel layer and a stainless steel cladding, and a triangular notch is provided in the middle of the workpiece, with the inner notch angle being ∠α of 84.54°.

[0023] Furthermore, both the ultrasonic generator and the ultrasonic receiver are fixed at an angle on the mounting plate, and the tail end of the ultrasonic receiver is electrically connected to an external display device.

[0024] Beneficial effects

[0025] In this invention, the process is applied to a 36mm thick stainless steel composite plate with specifications of 310S+Q245R. Taking this plate as an example, the welding process exhibits several advantages: the base layer welding efficiency is three times higher than that of traditional shielded metal arc welding, the overall working time is reduced by 40%, and the overall welding efficiency is significantly improved; the amount of stainless steel welding rods used is reduced by 40%, the rework rate is reduced significantly from 50% to 1.5%, and the overall cost is reduced by 25%, effectively saving costs; the mechanical linkage between ultrasonic waves and CCD and the welding device (such as lifting components) is also beneficial. The lifting and rotating components, along with data exchange, form a complete closed loop of "detection-analysis-control," thus increasing the flaw detection pass rate from 50% to 98.5%. Furthermore, through 20 high-temperature rapid cooling cycle crack tests under simulated working conditions (test conditions: 6-ton load, water cooling at 1000℃), the joint showed no cracks or deformation, demonstrating excellent quality performance. In summary, this welding process forms an independent and controllable composite plate welding process, filling the gap in domestic thick-walled composite plate welding technology and promoting the large-scale application of stainless steel composite plates in the field of high-end equipment.

[0026] This method employs a double-sided V-shaped asymmetric bevel design with a "wide outer layer and narrow inner layer" to adapt to the material differences between the base layer and the cladding layer, ensuring sufficient penetration of the base layer while reducing the dilution rate of the cladding layer. Strict control of heat input (≤1.5kJ / mm), interpass temperature (≤150℃), and welding speed suppresses grain coarsening and thermal stress concentration, reducing defects such as cracks and porosity. The intelligent control device presets parameters and generates a welding torch movement plan, combining lifting and rotating components to achieve precise control of the welding torch height and workpiece rotation, ensuring stable welding posture. A CCD camera and a tilted, fixed ultrasonic flaw detection component work together to achieve real-time monitoring of the welding process and comprehensive post-weld flaw detection, improving the efficiency and accuracy of quality inspection. This process, through optimized structural design, precise parameter control, and intelligent equipment collaboration, effectively solves the challenges of material matching, thermal stress control, and quality inspection in the welding of stainless steel composite plates, making it suitable for welding needs in fields such as high-precision pressure vessels. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0028] Figure 1 This is one of the structural schematic diagrams of the present invention;

[0029] Figure 2 This is the second structural schematic diagram of the present invention;

[0030] Figure 3 This is a schematic diagram of the lifting component in this invention;

[0031] Figure 4 This is a schematic diagram of the rotating component in this invention;

[0032] Figure 5 This is a schematic diagram of the bevel structure of the stainless steel composite plate in this invention;

[0033] Figure 6 This is a flowchart of the welding process in this invention.

[0034] The labels in the diagram represent: 1. Workbench; 11. Side column; 12. Angle bracket; 13. Connecting block; 2. Lifting assembly; 21. Cylinder; 22. Side rod; 23. Side plate; 3. Mounting plate; 31. Ultrasonic generating assembly; 32. Welding torch; 33. Ultrasonic receiver; 4. Rotating assembly; 41. Base platform; 42. Drive motor; 421. Driving gear; 43. Top plate; 44. Bottom cylinder; 45. Driven gear; 451. Rotating rod; 46. Locking ring; 47. Machining table; 5. Mounting assembly; 51. Mounting rod; 52. Locking block; 53. Industrial CCD camera; 6. Carbon steel layer; 7. Stainless steel cladding; 8. Workpiece. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] The present invention will be further described below with reference to embodiments.

[0037] Example 1: A fusion welding process for stainless steel composite plates, as shown in the attached figure. Figure 1 -Appendix Figure 6 ,include:

[0038] Step 1: ① Pre-welding preparation: Prepare the stainless steel composite plate and welding materials, and perform beveling; ② Workpiece pretreatment: Use machining to finely process the bevel interface, and use an angle grinder to remove the bevel and both sides until the metal luster is exposed; ③ Prepare and fix the welding machine, input the preset welding control parameters into the intelligent control device, adjust the welding position, generate the welding torch 32 movement and height adjustment scheme, and perform the welding operation. Also, pre-prepare the welding materials.

[0039] Step 2: Perform welding according to the welding process sequence: ① Welding of the inner base layer Q245R carbon steel; ② Welding of the outer transition layer stainless steel fusion zone; ③ Welding of the outer cladding layer 310S stainless steel.

[0040] Step 3: Post-weld flaw detection. The flaw detection device includes an ultrasonic generator 31 and an ultrasonic receiver 33, both of which are fixed on the mounting plate 3. The welding torch 32 is fixed in the middle of the mounting plate 3. One side of the mounting plate 3 is fixedly connected to the lifting assembly 2. A rotating assembly 4 is provided at the bottom of the welding torch 32. The workpiece 8 is placed at the top of the rotating assembly 4. The rotating assembly 4 and the lifting assembly 2 are both fixed at the top of the worktable 1. A side column 11 is fixed on one side of the top of the worktable 1. A mounting assembly 5 is fixed on the side column 11. A CCD camera 53 is fixed at the end of the mounting assembly 5. The camera lens is equipped with a high-temperature resistant protective cover (temperature resistance ≥200℃) and a variable focus optical system. The CCD camera (53) is connected to the intelligent control device in the welding machine via Ethernet, supporting an image acquisition rate of 30 frames per second. The intelligent control device has a vision control system, and the vision control system has an image recognition algorithm.

[0041] In step 1①, the bevel adopts a double-sided V-shaped asymmetrical bevel with "wider outer side and narrower inner side". The specific parameters are as follows: the outer cladding material is 310S stainless steel: bevel angle 42°, depth 12mm, blunt edge 2mm, root gap 2mm, which can effectively increase the CO2 welding filling space ratio to 67% and reduce the amount of stainless steel welding rods by 40%; the welding stress concentration coefficient and residual stress peak value are reduced; the inner base material is Q245R carbon steel: bevel angle 28°, depth 24mm, blunt edge 2mm, root gap 2mm.

[0042] In step 1②, during the finishing process, the surface roughness Ra of workpiece 8 is ≤12.5μm; the grinding range of oil stains and rust on the bevel and both sides is 200mm; before carbon arc gouging to clean the root, lime or talcum powder solution is applied to 200mm on both sides of the bevel to prevent splashing and adhesion.

[0043] In step 1③, the welding equipment includes: CO2 welding machine: current accuracy ±5A, gas flow rate 15-20L / min, equipped with ER50-6 solid core welding wire; arc welding machine: current accuracy ±3A, suitable for short arc operation of shielded metal arc welding, equipped with A307 for the transition layer and A407 as the cladding material stainless steel welding rods. Welding material pretreatment: A307 and A407 welding rods need to be dried at 350℃ for 2 hours and placed in a 100-150℃ heat preservation container for use as needed.

[0044] In step 2①, the inner base layer welding adopts a multi-layer, multi-pass CO2 gas shielded welding method, with the thickness of each weld layer controlled at 2-3mm. Straight-line welding or small-amplitude oscillation is used to control the heat input ≤1.5kJ / mm, suppressing grain coarsening. After the inner base layer welding, carbon arc gouging is performed on the root of the outer weld of the cylinder to a depth of 3-4mm to ensure no defects such as incomplete fusion before carbon steel layer filling welding. In step ②, the outer transition layer stainless steel fusion zone welding adopts a short-arc shielded metal arc welding method with a welding speed of 10-15cm / min; interpass temperature ≤150℃; weld height 2-3mm lower than the base metal surface; process parameters: current 130-160A, arc voltage 20-22V, welding speed 10-15cm / min; metallurgical control: the penetration depth is controlled ≤ using narrow bevel short-arc technology. 2mm, reducing the dilution of the transition layer by the base layer; precisely adjust the Cr / Ni element ratio in the weld (Cr≥25%, Ni≥20%) to stabilize the ferrite content at 4-6%, improving crack resistance by 50%. In ③, the outer cladding layer of 310S stainless steel is welded using a short arc welding method with a welding speed of 12-18cm / min; the angle between the electrode and the welding direction is 70°-80° to ensure a smooth transition at the weld edge. Process parameters: current 160-180A, voltage 22-24V. Forming control: monitor the shape of the molten pool in real time and adjust the weld width by wrist swing to ensure that the surface forming tolerance is ≤±0.5mm; thoroughly remove slag between layers to avoid slag inclusion defects. After welding, perform non-destructive testing on the entire weld and use ultrasonic testing (UT) to inspect the inside of the weld, which meets the ultrasonic testing qualification standard. The weld is aesthetically pleasing, with uniform width and smooth transition at the joint. It is free from defects such as cracks, undercut, lack of fusion, and porosity. Non-destructive testing is performed on the coating to simulate the on-site environment and conduct corrosion resistance chemical tests, such as copper sulfate test and blue dot test, to ensure that it meets the corrosion requirements of the service environment.

[0045] The "wide on the outside, narrow on the inside" double-sided V-shaped asymmetrical bevel design is adapted to the material differences between the 310S stainless steel cladding and the Q245R carbon steel base layer. The 42° and 28° bevel angles respectively meet the requirements for shallow penetration depth of the cladding (12mm) and deep penetration depth of the base layer (24mm). Combined with a 2mm blunt edge and root gap, it reduces the cladding dilution rate to ensure corrosion resistance and ensures the welding strength of the base layer. Step 1② requires surface roughness of the workpiece (Ra≤12.5μm) and grinding within a 200mm range on both sides of the bevel. Combined with the operation of applying lime or talcum powder solution before carbon arc gouging, oil stains and rust can be thoroughly removed and splash adhesion can be prevented, reducing the risk of defects such as porosity and inclusions from the source. During the welding process, the inner base layer is subjected to multi-layer, multi-pass CO2 gas shielded welding with a weld thickness of 2-3 mm per layer and a heat input of ≤1.5 kJ / mm, which effectively suppresses grain coarsening. The outer transition layer and cladding layer are operated by short arc welding with shielded metal arc welding, with welding speeds of 10-15 cm / min and 12-18 cm / min and interpass temperature of ≤150℃, to further ensure the weld formation quality and avoid the generation of hot cracks.

[0046] Matching materials are selected for different welding layers (ER50-6 solid welding wire for the base layer, A307 and A407 welding electrodes for the transition and cladding layers). Precise drying (350℃×2 hours) and heat preservation (100-150℃) are used to ensure the activity of the welding materials, improve the mechanical properties and corrosion resistance of the weld. Carbon arc gouging (3-4mm depth) and beveling pretreatment (roughness Ra≤12.5μm, grinding within 200mm range) are designed for the characteristics of composite plates to avoid spatter adhesion and the influence of impurities. The phased welding process (base layer, transition layer, cladding layer) is adapted to the different material requirements, reducing rework and improving production efficiency.

[0047] Angle bracket 12 is fixed on the side wall of the side column 11. A sliding rod is fixed between the angle brackets 12, and a docking block 13 is fixed on the sliding rod. The docking block 13 is fixedly connected to the mounting rod 51 in the mounting assembly 5. The end of the mounting rod 51 is fixedly connected to the locking block 52. The locking block 52 is inserted and fixed to the industrial CCD camera 53.

[0048] The ultrasonic generator assembly 31 and ultrasonic receiver 33, fixed at an angle, combined with pulse signals of specific frequencies, can perform targeted inspections based on the different characteristics of the substrate and coating. A 2MHz low-frequency signal can accurately detect internal cracks equivalent to ≥0.5mm in the substrate, while a 5MHz high-frequency signal can identify surface micro-cracks ≥0.1mm in the coating, significantly improving the defect detection rate. Furthermore, the thermocouple built into the ultrasonic receiver automatically activates a signal attenuation compensation algorithm in high-temperature environments, ensuring that detection accuracy remains unaffected in welding environments ranging from 150-300℃, accurately locating the defect position and size. In addition, by raising and lowering the mounting plate 3 and rotating the workpiece 8, the probe scans along a spiral trajectory, and the resulting three-dimensional defect distribution map, reconstructed by software, visually displays the defect distribution, providing a reliable basis for subsequent quality assessment and processing.

[0049] The lifting assembly 2 includes a side rod 22 fixed to the side column 11, a cylinder 21 fixed to the side plate 23, and a mounting plate 3 fixed to the output end of the cylinder 21.

[0050] The rotating assembly 4 includes a base 41 fixed to the top of the worktable 1, a bottom cylinder 44 fixed to the top of the base 41, and a drive motor 42. The output end of the drive motor 42 is connected to the drive gear 421. The drive gear 421 meshes with the driven gear 45. The middle part of the driven gear 45 is fixedly connected to the rotating rod 451. The bottom of the rotating rod 451 is sleeved in the bottom cylinder 44. The top of the rotating rod 451 is fixedly connected to the processing table 47. A locking ring 46 is sleeved on the top of the rotating rod 451 at the top of the bottom cylinder 44. The top of the drive gear 421 is fixedly connected to the top plate 43, and the rotating rod 451 passes through the top plate 43.

[0051] Workpiece 8 includes a carbon steel layer 6 and a stainless steel cladding layer 7. A triangular notch is provided in the middle of workpiece 8, and the angle of the inner notch is ∠α, which is 84.54°. The ultrasonic generating component 31 and the ultrasonic receiver 33 are both fixed at an angle on the mounting plate 3. The tail end of the ultrasonic receiver 33 is electrically connected to an external display device. The tilted fixing of the ultrasonic generating component 31 and the ultrasonic receiver 33 on the mounting plate 3, together with the centrally positioned welding torch 32, can achieve height synchronous adjustment with the lifting component 2 (driven by cylinder 21). Combined with the rotating component 4 (the drive motor 42 drives the processing table 47 to rotate through gears (drive gear 421-driven gear 45)), it can perform all-round scanning of complex structures such as the triangular notch (inner angle 84.54°) of the workpiece, and accurately detect the interface and internal defects of the carbon steel layer 6 and the stainless steel cladding layer 7. The industrial CCD camera 53 on the side column 11 is flexibly positioned via components such as a sliding rod and mounting rod 51, enabling real-time monitoring of the bevel pretreatment status, weld pool formation during welding, and electrode angle (70°-80°). This, combined with ultrasonic testing, forms a dual "visual + acoustic" verification, ensuring thorough defect detection. Furthermore, the pretreatment of A307 and A407 electrodes—drying them at 350°C for 2 hours and holding them at 100-150°C—along with the stable output of the CO2 welding machine (current accuracy ±5A) and the arc welding machine (current accuracy ±3A), further guarantees the performance of welding materials and reduces welding defects.

[0052] The rotating assembly 4 includes a locking ring 46 that limits the rotation rod 451 and supports the top plate 42, ensuring the stability of the workpiece 8 during rotation. This is particularly suitable for welding workpieces 8 with a triangular notch in the center. The rigid connection between the lifting assembly 2 and the mounting plate 3 enables synchronous lifting of the welding torch 32 and the inspection assembly, improving operational continuity. Through precise matching of mechanical structure and process parameters, the overall system can meet the welding requirements of dissimilar materials such as carbon steel layer 6 and stainless steel cladding layer 7, and can also adapt to the processing of complex structures of workpiece 8. This significantly reduces manual intervention and raises the welding qualification rate and inspection efficiency to a new level, making it particularly suitable for fields with stringent requirements for corrosion resistance and strength, such as pressure vessels.

[0053] Example 2: Based on Example 1, CO2 welding with CO2 shielding gas and ER50-6 solid wire was used to weld the carbon steel layer. A transition layer was welded using CO2 shielding gas and ER309L flux-cored wire, leveraging the good arc stability and fast deposition rate of ER309L to ensure the quality of the transition layer. A gas metal arc welding (MAG) process using a mixture of inert argon (Ar) and oxidizing gas (CO2) as the shielding gas, combined with ER310 solid wire, was used to weld the cladding layer, utilizing the high efficiency of ER310 solid wire to improve the welding speed of the cladding layer. However, after multiple welding experiments, it was found that severe alloy burn-off occurred during CO2 welding, and microscopic strip-like defects invisible to the naked eye frequently appeared during the welding process.

[0054] Example 3: Based on Example 1, CO2 welding with CO2 shielding gas and ER50-6 solid wire was used to weld the carbon steel layer, submerged arc welding with ER309L wire was used to weld the transition layer, and submerged arc welding with ER310 wire was used to weld the cladding layer. Although this method significantly increases the welding speed, the heat input of submerged arc welding is relatively large. During the welding process, excessive fusion of the base layer and cladding metals is likely to occur, leading to dilution of the alloy composition of the stainless steel cladding by the base metal and a larger heat-affected zone. Under the action of welding thermal cycling, the composite plate may develop defects such as deformation and cracks, especially at the junction of the base layer and cladding. Due to the differences in physical and chemical properties between the two materials, the content of alloys such as chromium and nickel is likely to increase, resulting in a brittle and hard structure, and defects such as incomplete fusion and cracks are prone to occur.

[0055] In summary, the welding method in Example 1 is superior to the other two examples in terms of efficiency, cost, and performance.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A stainless steel clad plate fusion welding process, characterized by, Comprising Step one: ① Before welding preparation: prepare stainless steel clad plate and welding materials, and carry out groove processing; ② Workpiece (8) pretreatment: adopt mechanical processing to finish machining on the groove interface, use angular sander to clean the groove and both sides until the metal luster is exposed; ③ Prepare and fix the welding machine, input the preset welding control parameters to the intelligent control device, adjust the welding position, generate the welding gun (32) movement and height adjustment scheme, and carry out welding operation, and pre-prepare the welding materials, Step two: carry out welding processing according to the welding process sequence, ① Inner base layer (Q245R carbon steel) welding; ② Outer transition layer (stainless steel fusion zone) welding; ③ Outer cladding layer (310S stainless steel) welding; Step three: post-welding flaw detection, the flaw detection device comprises an ultrasonic wave generating assembly (31) and an ultrasonic wave receiver (33), and both are fixed on the mounting plate (3), the welding gun (32) is fixed in the middle of the mounting plate (3), one side of the mounting plate (3) is fixedly connected with the lifting assembly (2), the bottom of the welding gun (32) is provided with a rotating assembly (4), the workpiece (8) is arranged at the top end of the rotating assembly (4), the rotating assembly (4) and the lifting assembly (2) are both fixed on the top end of the workbench (1), one side of the top end of the workbench (1) is fixedly connected with a side column (11), the side column (11) is fixedly connected with a mounting assembly (5), the tail end of the mounting assembly (5) is fixedly connected with a CCD camera (53), the camera lens is provided with a high-temperature-resistant protective cover (temperature resistance ≥ 200 DEG C) and a variable-focus optical system, the CCD camera (53) is connected with the intelligent control device in the welding machine through Ethernet, supports an image acquisition rate of 30 frames per second, and the intelligent control device is provided with a visual control system, and the visual control system is provided with an image recognition algorithm.

2. A stainless steel clad plate fusion welding process according to claim 1, wherein In step one ①, the groove adopts "outer wide and inner narrow" double-sided V-shaped asymmetric groove, and the specific parameters are as follows: the outer cladding layer material is 310S stainless steel: the groove angle is 42°, the depth is 12mm, the blunt edge is 2mm, and the root gap is 2mm; the inner base layer material is Q245R carbon steel: the groove angle is 28°, the depth is 24mm, the blunt edge is 2mm, and the root gap is 2mm.

3. The stainless steel clad plate fusion welding process according to claim 1, wherein In step one ②, during the finishing process, the surface roughness of the workpiece (8) is Ra≤12.5μm; the oil stain and rust polishing range of the groove and both sides is 200mm; before carbon arc gouging, lime (or talc powder) solution is brushed on both sides of the groove within 200mm to prevent splashing and adhesion.

4. The stainless steel clad plate fusion welding process of claim 1 wherein, In step one ③, the welding equipment comprises: CO2 welding machine / welding gun (32): current accuracy ±5A, gas flow 15-20L / min, matched with ER50-6 solid wire; arc welding machine / welding gun (32): current accuracy ±3A, matched with A307 for transition layer and A407 as cladding layer material stainless steel electrode, welding material pretreatment: the A307 and A407 electrodes need to be dried at 350 DEG C for 2 hours and taken out from the 100-150 DEG C heat preservation barrel.

5. A stainless steel clad plate fusion welding process according to claim 4, wherein In step two ①, the inner base layer welding adopts CO2 gas shielded welding (multi-layer multi-pass welding) method, and the thickness of each layer of weld is controlled at 2-3 mm, and linear operation or small amplitude swing is adopted, and the heat input is controlled at ≤1.5 kJ / mm, and the grain coarsening is inhibited; after the inner base layer welding, the carbon arc air gouging is used to clean the root of the outer side weld of the cylinder, and the cleaning depth is 3-4 mm, in ②, the outer side transition layer (stainless steel fusion zone) welding adopts the welding method of stick arc welding (short arc operation), and the welding speed is 10-15 cm / min; the interlayer temperature is ≤150℃, and the weld height is lower than the surface of the base material by 2-3 mm, in ③, the outer side cladding layer (310S stainless steel) welding adopts the welding method of stick arc welding (short arc operation), and the welding speed is 12-18 cm / min; the angle between the welding rod and the welding direction is 70°-80°.

6. The stainless steel clad plate fusion welding process of claim 1 wherein, The corner code (12) is fixed on the side wall of the side column (11), the sliding rod is fixed between the corner codes (12), and the butt joint block (13) is fixed on the sliding rod, the butt joint block (13) is fixedly connected with the mounting rod (51) in the mounting assembly (5), the tail end of the mounting rod (51) is fixedly connected with the clamping block (52), and the clamping block (52) is insertedly fixed with the industrial CCD camera (53).

7. The stainless steel clad plate fusion welding process of claim 1 wherein, The lifting assembly (2) comprises a side rod (22) fixed with the side column (11), a gas cylinder (21) fixed with a side plate (23), and a mounting plate (3) fixed with the output end of the gas cylinder (21).

8. The stainless steel clad plate fusion welding process of claim 1 wherein, The rotating assembly (4) comprises a bottom table (41) fixed to the top end of the workbench (1), a bottom cylinder (44) fixed to the top end of the bottom table (41), and a driving motor (42), the output end of the driving motor (42) is in transmission connection with a driving gear (421), the driving gear (421) is in meshing fixation with a driven gear (45), the middle part of the driven gear (45) is fixedly connected with a rotating rod (451), the bottom part of the rotating rod (451) is sleeved in the bottom cylinder (44), the top end of the rotating rod (451) is fixedly connected with a machining table (47), a clamping ring (46) is sleeved on the top end of the bottom cylinder (44), the top end of the driving gear (421) is fixedly connected with a top plate (43), and the rotating rod (451) penetrates through the top plate (43).

9. The stainless steel clad plate fusion welding process of claim 1 wherein, The workpiece (8) comprises a carbon steel layer (6) and a stainless steel cladding layer (7), and a triangular slot is formed in the middle part of the workpiece (8), and the inner side slot angle is ∠α, which is 84.54°.

10. The stainless steel clad plate fusion welding process of claim 1 wherein, The ultrasonic wave generating assembly (31) and the ultrasonic wave receiver (33) are fixed on the mounting plate (3) in an inclined manner, and the tail end of the ultrasonic wave receiver (33) is electrically connected with an external display device.

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