A device and method for preventing intergranular corrosion of a stainless steel clad plate weld

Abstract

The application discloses a device and method for preventing intergranular corrosion of a stainless steel clad plate weld, and belongs to the technical field of preventing intergranular corrosion of a stainless steel clad plate weld. The prevention device comprises a welding / cooling device, a conveying device, a detection device, a heat treatment device and an overall control device, and the detection device is in communication connection with the heat treatment device. The prevention method selects ultra-low carbon welding material containing titanium elements, and welding is performed by using welding process parameters of small wire energy, wide weld and small current. After welding, a copper backing plate and a spraying water cooling mode are used to improve the cooling speed and reduce the residence time of the weld in the sensitization temperature range. After falling below the sensitization temperature range, the weld is immediately conveyed to the heat treatment device for heat treatment. The heat treatment device automatically sets the holding temperature and time according to alloy elements, improves the mechanical properties of the base metal, ensures the intergranular corrosion resistance of the cladding metal, and achieves the purpose of preventing intergranular corrosion.

Description

Technical Field

[0001] This invention relates to the field of preventing intergranular corrosion in weld seams of stainless steel composite plates, specifically to a device and method for preventing intergranular corrosion in weld seams of stainless steel composite plates. Background Technology

[0002] Stainless steel composite panels are commonly manufactured using explosive bonding. The stainless steel cladding primarily withstands the corrosive effects of the medium, while the base layer ensures the structural strength and rigidity, each utilizing its own material properties. During container manufacturing, post-weld heat treatment is typically used to improve the performance of the base material, or rapid cooling is employed to enhance the intergranular corrosion resistance of the cladding. However, because post-weld heat treatment temperatures are usually within the sensitization temperature range for stainless steel intergranular corrosion, it reduces the cladding's resistance to intergranular corrosion. Rapid cooling can shorten the time the cladding remains within the sensitization temperature range, but it increases the risk of hardened structures forming in the base layer, thus reducing the base material's performance. Therefore, existing stainless steel composite panels either have good base material properties but low cladding resistance to intergranular corrosion, or strong cladding resistance but poor base material properties; they cannot simultaneously possess good base mechanical properties and cladding resistance to intergranular corrosion. Summary of the Invention

[0003] The present invention addresses the problem that existing technical solutions are too simplistic and provides a solution that is significantly different from existing technologies. It mainly provides a device and method for preventing intergranular corrosion in the weld seams of stainless steel composite plates, thereby solving the technical problem mentioned in the background that stainless steel composite plates cannot simultaneously possess good mechanical properties of the base layer and good resistance to intergranular corrosion of the coating.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0005] An apparatus for preventing intergranular corrosion in weld seams of stainless steel composite plates includes a welding / cooling device, a heat treatment device, and an overall control device, as well as a transfer device disposed between the welding / cooling device and the heat treatment device, and a detection device disposed above the transfer device; the detection device includes a laser spectrometer and a thickness gauge, the heat treatment device includes a specimen placement stage, a heat treatment induction heating device disposed on the specimen placement stage, and a heat treatment control device, the laser spectrometer and the thickness gauge being signal-connected to the heat treatment control device, and the heat treatment control device being used to control the heat treatment induction heating device.

[0006] Furthermore, the welding / cooling device includes: a welding / cooling operating table, a copper pad, and a spraying mechanism, wherein the copper pad is disposed on the welding / cooling operating table, and the spraying mechanism is disposed directly above the copper pad.

[0007] Furthermore, the transmission device includes a transmission equipment and a transmission power mechanism for driving the transmission equipment.

[0008] Furthermore, a spring is connected to the top of the detection device.

[0009] The present invention also provides a method for preventing intergranular corrosion in weld seams of stainless steel composite plates, using the above-mentioned apparatus, the method comprising the following steps:

[0010] S1. Weld the base layer, transition layer and cladding layer of the stainless steel composite plate in sequence, using welding process parameters of low current, fast welding and low heat input.

[0011] S2. After the overall welding is completed, the surface coating is cleaned, and the temperature is quickly reduced to 400℃ by spraying water through a spraying mechanism to obtain a welded specimen of stainless steel composite plate.

[0012] S3. Place the welding test piece onto the transmission device, start the transmission device, and transport the welding test piece to the bottom of the testing device;

[0013] S4. The testing device performs elemental spectral analysis on the welded specimen using a laser spectrometer to determine the content of various elements and transmits the data to the heat treatment control device; the testing device measures the thickness of the welded specimen using a thickness gauge and transmits the thickness data to the heat treatment control device.

[0014] S5. The heat treatment control device determines the heat treatment temperature and holding time, as well as the corresponding heating and cooling rates, based on the heat treatment process design calculation formula, thereby formulating the heat treatment process.

[0015] S6. After the test is completed, the transmission device continues to transfer the welded specimen to the specimen placement table. The heat treatment control device starts the heat treatment induction heating device and closes it. The initial temperature of the heat treatment induction heating device is controlled to be 400℃. After the welded specimen is rapidly heated to 400℃, the temperature continues to rise.

[0016] S7. When the welding specimen reaches 450℃, hold for 5 minutes, and then continue to increase the temperature; when the welding specimen reaches 500℃, hold for 5 minutes, and then continue to increase the temperature; when the welding specimen reaches 550℃, hold for 5 minutes, and then continue to increase the temperature; when the welding specimen reaches the heat treatment temperature T, start holding at the temperature of T±10℃ for a holding time of t.

[0017] S8. After the heat preservation is completed, the welding test piece begins to cool down according to the required cooling rate. The heat treatment induction heating device (6) adjusts the heating power according to the heat treatment process.

[0018] S9. After the welding test piece cools down to below 400℃, fully open the heat treatment induction heating device (6); after the welding test piece cools down to room temperature, take out the welding test piece;

[0019] S10. Conduct tests on the intergranular corrosion resistance of stainless steel welds on welded specimens.

[0020] Further, in step S4, the content of element Cr is determined by a laser spectrometer; in step S5, the heat treatment process design calculation formula is as follows: when the Cr content is ≤0.5% and the thickness δ>19, the heat treatment temperature T=600×α-20, where α takes the value of 1-1.2; when the Cr content is >0.5% and the thickness δ>13, the heat treatment temperature T=(600+a)×β-20, where β takes the value of 1-1.1, and a takes the value of 100; the heat treatment holding time t=(δ / 2)2×π×ρ / (4×k)×α, where δ is the thickness, ρ is the density, k is the thermal conductivity coefficient, and α is the coefficient of variation; the heating rate υ=γb, where b takes the value of 55℃ / h, and γ takes the value of 1-4; the cooling rate υ=ηc, where c takes the value of 55℃ / h, and η takes the value of 1-5.

[0021] Furthermore, during the welding of the base layer in step S1, the weld is ensured to be concave, with a certain degree of fusion between the weld and both sides of the bevel, achieving a fusion ratio of 20-30%. The weld and bevel have a smooth transition, reducing stress concentration and lowering the tendency for cracks to appear during the subsequent rapid cooling process. The interpass temperature of the base layer welding is strictly controlled to be <300℃, and the quality of interpass cleaning is strictly controlled to eliminate defects such as slag inclusions and porosity between layers, reducing the probability of hardened structures appearing between grains.

[0022] Furthermore, when welding the transition layer in step S1, the welding thickness is controlled so that both the base layer and the cladding layer are fused together. The fusion thickness on the cladding layer side is relatively thicker (≥2mm) to increase the tensile strength during rapid cooling.

[0023] Furthermore, during the welding of the cladding layer in step S1, the interlayer temperature is controlled below 100°C. After cleaning the surface coating, water is sprayed through a spraying mechanism and a copper backing plate to quickly reduce the temperature of the weld, thereby reducing the time the weld stays above 400°C and ensuring the weld's resistance to intergranular corrosion.

[0024] Furthermore, in step S4, the detection device uses an adjustable spring to bring the laser spectrometer into contact with the surface of the welded specimen for elemental spectral analysis.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) This invention includes a heat treatment device for post-weld heat treatment of stainless steel composite plates and a laser spectrometer and thickness gauge for detecting the post-weld stainless steel composite plates. The laser spectrometer is used to detect the elemental composition of the weld metal (mainly Cr). Based on the measurement data, the heat treatment holding temperature and time are set in a targeted manner. Considering the influence of the cladding weld, the lower limit of α or β value is taken, and the heat treatment temperature is further reduced by 20°C. This reduces the diffusion movement of carbon atoms and the formation of Cr by carbon atoms and Cr atoms. 23 The probability and quantity of C6 are controlled to avoid chromium depletion at grain boundaries; on the other hand, at the same cooling rate, the residence time of the weld cladding in the sensitization temperature range of 420℃ to 850℃ is reduced, shortening the formation of Cr by carbon atoms and Cr atoms. 23 C6 reaction time, reducing Cr formation 23 The amount of C6 is increased to avoid chromium depletion at grain boundaries, thereby reducing the probability of intergranular corrosion in the coating. Thus, this invention, while eliminating residual stress in the weld and improving the mechanical properties of the weld base layer of the stainless steel composite plate through heat treatment, also reduces the impact of heat treatment on the weld coating of the stainless steel composite plate, promoting the maintenance of the coating's resistance to intergranular corrosion.

[0027] (2) The present invention also sets the heating and cooling rates of the heat treatment device according to the detection data of the detection device. The cooling rate is 55-280℃ / h. If the cooling rate is greater than 280℃ / h, the cooling rate is too fast, and the base carbon steel is prone to hardening structure, which increases the hardness of the base carbon steel, reduces the plasticity and toughness of the base carbon steel, and affects the performance of the material. If the cooling rate is less than 55℃ / h, it increases the residence time of the weld cladding in the sensitization temperature range of 420℃-850℃, prolonging the formation of Cr by carbon atoms and Cr atoms. 23 The reaction time of C6 increases the Cr 23 The higher C6 content increases the probability of chromium depletion at grain boundaries, thus increasing the risk of intergranular corrosion in the coating. This invention addresses this by adjusting the heating and cooling rates of the induction heating device during heat treatment to better control the temperature rise and fall of the welded specimen, thereby avoiding impacting the mechanical properties of the stainless steel composite plate's base material and simultaneously promoting the maintenance of the coating's resistance to intergranular corrosion.

[0028] (3) In this invention, the detection device and the heat treatment control device are connected by signal. The detection device directly sends the data of the stainless steel composite plate after welding to the heat treatment control device. Based on the measurement data, the heat treatment control device automatically sets the heat treatment temperature and time after welding, as well as the corresponding heating and cooling rates, according to the heat treatment process design calculation formula. This achieves highly automated control and is easy to use. Furthermore, the heat treatment process is designed by completing the heat treatment process design calculation formula, which improves the accuracy of the heat treatment process.

[0029] (4) This invention also includes a welding / cooling device, comprising an operating table, a copper backing plate, and a spraying mechanism. During welding of the cladding, the interlayer temperature is controlled below 100°C. After cleaning the surface coating, water is sprayed through the spraying mechanism and the copper backing plate to quickly lower the weld temperature, reducing the weld's dwell time above 400°C and ensuring the weld's resistance to intergranular corrosion. After the overall welding is completed, the temperature is rapidly reduced again to 400°C using the spraying mechanism. Thus, this invention achieves rapid cooling after welding, shortening the dwell time of the stainless steel composite plate weld within the sensitization temperature range and improving the cladding's resistance to intergranular corrosion. A special post-weld heat treatment is then performed to improve the mechanical properties of the stainless steel composite plate weld base layer while maintaining the cladding's resistance to intergranular corrosion.

[0030] (5) The present invention uses welding process parameters of low current, fast welding, low heat input, low heat input, and wide weld seam to weld the base layer, transition layer and cladding layer in sequence. By controlling the fusion ratio between the weld seam and the two sides of the bevel, the weld seam and the bevel are smoothly transitioned, reducing stress concentration and reducing the tendency of cracks to appear during the rapid cooling process in the later stage. Furthermore, by strictly controlling the interpass temperature and the quality of interpass cleaning, defects such as slag inclusions and porosity between interpasses are eliminated, and the probability of hardened structure appearing between grains is reduced. By controlling the interpass temperature, the dwell time of the stainless steel composite plate weld seam in the sensitization temperature range can also be shortened, which is conducive to improving the weld seam quality of the stainless steel composite plate.

[0031] In summary, this invention, by designing a device and method for preventing intergranular corrosion in weld seams of stainless steel composite plates, can improve the mechanical properties of the substrate while maintaining the intergranular corrosion resistance of the coating, reducing material costs and extending the service life of the structure.

[0032] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a device for preventing intergranular corrosion in weld seams of stainless steel composite plates according to the present invention.

[0034] Figure 2 This is a schematic diagram of the bevel and weld of the stainless steel composite plate in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of two samples used in an intergranular corrosion experiment according to an embodiment of the present invention.

[0036] Figure label:

[0037] 1. Welding / cooling operating table; 2. Copper pad; 3. Spraying mechanism; 4. Conveying equipment; 5. Conveying power mechanism; 6. Heat treatment induction heating device; 7. Heat treatment control device; 8. Overall control device; 9. Detection device; 10. Spring; 11. Specimen placement table. Detailed Implementation

[0038] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0039] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] Example

[0042] Please refer to the appendix carefully. Figure 1 A device for preventing intergranular corrosion of weld seams in stainless steel composite plates includes a welding / cooling device, a heat treatment device, and an overall control device 8, as well as a transfer device located between the welding / cooling device and the heat treatment device and a detection device 9 located above the transfer device.

[0043] The welding / cooling device includes a welding / cooling operating table 1, a copper pad 2, and a spraying mechanism 3. The copper pad 2 is disposed on the welding / cooling operating table 1, and the spraying mechanism 3 is disposed directly above the copper pad 2.

[0044] The transmission device includes a transmission device 4 and a transmission power mechanism 5 for driving the transmission device 4.

[0045] The detection device 9 includes a laser spectrometer and a thickness gauge, and a spring 10 is connected to the top of the detection device 9.

[0046] The heat treatment apparatus includes a specimen placement platform 11 and a heat treatment induction heating device 6 and a heat treatment control device 7 disposed on the specimen placement platform 11. The laser spectrometer and thickness gauge are respectively connected to the heat treatment control device 7. The heat treatment control device 7 is used to control the heat treatment induction heating device 6. An infrared thermometer is also provided for detecting the temperature of the welded specimen.

[0047] The overall control device 8 is electrically connected to the welding / cooling device, heat treatment device, transmission device, and detection device 9, respectively, and is used to control the other devices.

[0048] Based on the above-mentioned preventive device, a method for preventing intergranular corrosion in weld seams of stainless steel composite plates includes the following steps:

[0049] (1) First weld the carbon steel base layer (such as...) Figure 2 As shown, ultra-low carbon welding materials containing titanium are selected, and welding process parameters of low current, fast welding, low heat input, low heat input, and wide weld bead are used for welding. At the same time, the weld bead is ensured to be concave, and there is a certain fusion between the weld bead and both sides of the bevel, reaching a certain fusion ratio (20-30%). The weld bead and the bevel have a smooth transition, reducing stress concentration and reducing the tendency of cracks to appear during the rapid cooling process in the later stage. The welding of the base layer must strictly control the interpass temperature (<300℃) and the quality of interpass cleaning to eliminate defects such as slag inclusions and porosity between layers and reduce the probability of hardened structure appearing in the intergranular space.

[0050] (2) Welding transition layer (e.g.) Figure 2 As shown), welding is carried out using a method of low current, fast welding, low heat input, low heat input, and wide weld seam. It is necessary to control the weld thickness, which is to fuse both the base layer and the cladding layer. The fusion thickness on the cladding layer side is relatively thicker (≥2mm) to increase the tensile strength during rapid cooling.

[0051] (4) Welding cladding (e.g.) Figure 2 As shown), welding is carried out using a method of low current, fast welding, low heat input, low heat input, and wide weld seam. The interpass temperature is controlled below 100℃. After cleaning the surface coating, water is sprayed by the spraying mechanism 3 and copper pad 2 to quickly reduce the temperature of the weld seam, reduce the dwell time of the weld seam above 400℃, and ensure the weld seam's resistance to intergranular corrosion.

[0052] (5) After the overall welding is completed, clean the coating on the surface and use the spraying mechanism 3 to quickly cool it down to 400℃;

[0053] (6) Place the stainless steel composite plate welding specimen onto the transmission device 4, start the transmission power mechanism 5, and the transmission device will start running to transport the welding specimen to the bottom of the testing device 9.

[0054] (7) The detection device 9 uses the adjusting spring 10 to bring the laser spectrometer into contact with the surface of the welded specimen for elemental spectral analysis, determine the content of various elements, mainly the content of Cr, and transmit the data to the heat treatment control device 7.

[0055] (8) The testing device 9 measures the thickness of the welded specimen and transmits the thickness data to the heat treatment control device 7.

[0056] (9) The heat treatment control device 7 determines the heat treatment temperature and holding time, as well as the corresponding heating and cooling rates, according to the heat treatment process design calculation formula, thereby formulating the heat treatment process.

[0057] The calculation formula for heat treatment process design is as follows: For Cr≤0.5% and thicknessδ>19, the heat treatment temperature T=600×α, where α takes the value of 1-1.2; For Cr>0.5% and thicknessδ>13, the heat treatment temperature T=(600+a)×β, where β takes the value of 1-1.1, and a takes the value of 100.

[0058] The heat treatment holding time t=(δ / 2)2×π×ρ / (4×k)×α, where δ is the thickness, ρ is the density, k is the thermal conductivity coefficient, and α is the variation coefficient;

[0059] The heating rate is υ=γb, where b is 55℃ / h and γ is in the range of 1-4;

[0060] The cooling rate is υ=ηc, where c is 55℃ / h and η is 1-5.

[0061] By using a testing device to determine the content of various elements and the thickness of the specimen, the heat treatment temperature is determined based on the element content and thickness. Taking into account the influence of the cladding weld, the lower limit of the α or β value is used, and the heat treatment temperature is further reduced by 20℃. This reduces the diffusion of carbon atoms and decreases the formation of Cr atoms from carbon atoms. 23 The probability and quantity of C6 are controlled to avoid chromium depletion at grain boundaries; on the other hand, at the same cooling rate, the residence time of the weld cladding in the sensitization temperature range of 420℃ to 850℃ is reduced, shortening the formation of Cr by carbon atoms and Cr atoms. 23 C6 reaction time, reducing Cr formation 23 The amount of C6 is increased to avoid chromium depletion at grain boundaries, thereby reducing the probability of intergranular corrosion in the coating.

[0062] The cooling rate should be between 55 and 280℃ / h. A cooling rate greater than 280℃ / h, being too rapid, can easily lead to hardened structures in the base carbon steel, increasing its hardness and reducing its ductility and toughness, thus affecting the material's performance. A cooling rate less than 55℃ / h increases the residence time of the weld cladding in the sensitization temperature range of 420℃ to 850℃, prolonging the formation of Cr atoms from carbon atoms. 23 The reaction time of C6 increases the Cr 23 The higher C6 content increases the probability of chromium depletion at grain boundaries, thus increasing the risk of intergranular corrosion in the coating.

[0063] (10) After the test is completed, the transmission device continues to transmit the welding test piece to the test piece placement table 11;

[0064] (11) The heat treatment control device 7 starts the heat treatment induction heating device 6 and closes it, and controls the initial temperature of the heat treatment induction heating device 6 to 400℃. After the welding specimen is rapidly heated to 400℃, the temperature continues to rise.

[0065] (12) The welding specimen reached 450℃, held for 5 minutes, and then continued to rise in temperature;

[0066] (13) The welding specimen reached 500℃, held for 5 minutes, and then continued to rise in temperature;

[0067] (14) After the welding specimen reaches 550℃, hold it at that temperature for 5 minutes, and then continue to raise the temperature.

[0068] (15) After the welded specimen reaches the heat treatment temperature T, it is held at the heat treatment temperature T ± 10℃ for a period of time t.

[0069] (16) After the heat preservation is completed, the welding specimen begins to cool down according to the required cooling rate, and the heat treatment induction heating device 6 adjusts the heating power according to the requirements.

[0070] (17) After the welding specimen is cooled to below 400℃, the heat treatment induction heating device 6 is fully turned on;

[0071] (18) After the welding test piece has cooled to room temperature, remove the welding test piece;

[0072] (19) Subsequently, the intergranular corrosion performance and mechanical properties of the stainless steel welds of the welded specimens were tested. The test results are shown in Table 1. Figure 3 The images show experimental results of intergranular corrosion in stainless steel welds. Figures (a) and (b) are experimental images of two samples, respectively. Due to the difference between close-up and long-range shots, Figures (a) and (b) appear slightly different.

[0073] Table 1. Experimental Results

[0074]

[0075]

[0076] In addition, tests were conducted on welded specimens in the existing technology, and the results were as follows: mechanical properties were qualified, but intergranular corrosion was unqualified (the specimens fractured when bent).

[0077] As can be seen from the above, compared with the prior art, the present invention can improve the mechanical properties of the base layer, while maintaining the intergranular corrosion resistance of the coating, reducing material costs, and extending the service life of the structure.

[0078] The present invention has been described by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvement made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, shall be within the protection scope of the present invention.

Claims

1. A device for preventing intergranular corrosion in weld seams of stainless steel composite plates, characterized in that: It includes a welding and cooling device, a heat treatment device and an overall control device (8), as well as a transmission device between the welding and cooling device and the heat treatment device and a detection device (9) above the transmission device; the detection device (9) includes a laser spectrometer and a thickness gauge, the heat treatment device includes a specimen placement stage (11) and a heat treatment induction heating device (6) and a heat treatment control device (7) on the specimen placement stage (11), the laser spectrometer and the thickness gauge are respectively connected to the heat treatment control device (7) by signal, and the heat treatment control device (7) is used to control the heat treatment induction heating device (6); The detection device (9) performs elemental spectral analysis on the welded specimen using a laser spectrometer, determines the content of various elements, and transmits the data to the heat treatment control device (7); the detection device (9) measures the thickness of the welded specimen using a thickness gauge and transmits the thickness data to the heat treatment control device (7); The heat treatment control device (7) determines the heat treatment temperature and holding time, as well as the corresponding heating and cooling rates, according to the heat treatment process design calculation formula, thereby formulating the heat treatment process. The content of element Cr was determined using a laser spectrometer; The heat treatment process design calculation formula is as follows: When the Cr content is ≤0.5% and the thickness δ>19mm, the heat treatment temperature T=600×α-20, where α takes the value of 1-1.2; when the Cr content is >0.5% and the thickness δ>13mm, the heat treatment temperature T=(600+a)×β-20, where β takes the value of 1-1.1, and a takes the value of 100; the heat treatment holding time t=(δ / 2)2×π×ρ / (4×k)×α, where δ is the thickness, ρ is the density, k is the thermal conductivity coefficient, and α is the variation coefficient; the heating rate υ=γb, where b takes the value of 55℃ / h, and γ takes the value of 1-4; the cooling rate υ=ηc, where c takes the value of 55℃ / h, and η takes the value of 1-5.

2. The device for preventing intergranular corrosion in weld seams of stainless steel composite plates according to claim 1, characterized in that: The welding and cooling device includes a welding and cooling operating table (1), a copper pad (2), and a spraying mechanism (3). The copper pad (2) is located on the welding and cooling operating table (1), and the spraying mechanism (3) is located directly above the copper pad (2).

3. The device for preventing intergranular corrosion in weld seams of stainless steel composite plates according to claim 2, characterized in that: The transmission device includes a transmission device (4) and a transmission power mechanism (5) for driving the transmission device (4).

4. The device for preventing intergranular corrosion in weld seams of stainless steel composite plates according to claim 3, characterized in that: The top of the detection device (9) is connected to a spring (10).

5. A method for preventing intergranular corrosion in weld seams of stainless steel composite plates, characterized in that: Using the apparatus of claim 4, the method comprises the following steps: S1. Weld the base layer, transition layer and cladding layer of the stainless steel composite plate in sequence; S2. After the overall welding is completed, the coating on the surface is cleaned and the surface is cooled down quickly by spraying water through the spraying mechanism (3) to 400°C, so as to obtain the welded specimen of stainless steel composite plate. S3. Place the welding test piece on the transmission device, start the transmission device, and transport the welding test piece to the bottom of the testing device (9); S4. The detection device (9) performs elemental spectral analysis on the welded specimen using a laser spectrometer, determines the content of various elements, and transmits the data to the heat treatment control device (7); the detection device (9) measures the thickness of the welded specimen using a thickness gauge and transmits the thickness data to the heat treatment control device (7). S5. Heat treatment control device (7) determines the heat treatment temperature and holding time, as well as the corresponding heating and cooling rates, according to the heat treatment process design calculation formula, thereby formulating the heat treatment process. S6. After the test is completed, the transmission device (9) continues to transmit the welding test piece to the test piece placement table (11). The heat treatment control device (7) starts the heat treatment induction heating device (6) to close and controls the initial temperature of the heat treatment induction heating device (6) to 400℃. After the welding test piece is rapidly heated to 400℃, the temperature continues to rise. S7. When the welding specimen reaches 450℃, hold for 5 minutes, and then continue to increase the temperature; when the welding specimen reaches 500℃, hold for 5 minutes, and then continue to increase the temperature; when the welding specimen reaches 550℃, hold for 5 minutes, and then continue to increase the temperature; when the welding specimen reaches the heat treatment temperature T, start holding at the temperature of T±10℃ for a holding time of t. S8. After the heat preservation is completed, the welding test piece begins to cool down according to the required cooling rate. The heat treatment induction heating device (6) adjusts the heating power according to the heat treatment process. S9. After the welding test piece cools down to below 400℃, fully open the heat treatment induction heating device (6); after the welding test piece cools down to room temperature, take out the welding test piece; S10. Conduct tests on the intergranular corrosion resistance of stainless steel welds on welded specimens.

6. The method for preventing intergranular corrosion in weld seams of stainless steel composite plates according to claim 5, characterized in that: When welding the base layer in step S1, ensure that the weld is concave and that there is a certain degree of fusion between the weld and both sides of the bevel, so that the fusion ratio reaches 20-30%. The weld and the bevel should have a smooth transition to reduce stress concentration and reduce the tendency for cracks to appear during the rapid cooling process in the later stage. The interpass temperature of the base layer welding should be strictly controlled to be <300℃, and the quality of the interpass cleaning should be strictly controlled to eliminate slag inclusions and porosity defects between the layers and reduce the probability of hardened structures appearing between grains.

7. The method for preventing intergranular corrosion in weld seams of stainless steel composite plates according to claim 5, characterized in that: When welding the transition layer in step S1, the welding thickness should be controlled to fuse both the base layer and the cladding layer.

8. A method for preventing intergranular corrosion in weld seams of stainless steel composite plates according to claim 5, characterized in that: In step S1, when welding the cladding, the interlayer temperature is controlled below 100℃. After cleaning the surface coating, water is sprayed through the spraying mechanism (3) and the copper pad (2) to quickly reduce the temperature of the weld, reduce the time the weld stays above 400℃, and ensure the weld's resistance to intergranular corrosion.

9. A method for preventing intergranular corrosion in weld seams of stainless steel composite plates according to claim 5, characterized in that: In step S4, the detection device (9) uses the spring (10) to bring the laser spectrometer into contact with the surface of the welded specimen for elemental spectral analysis.

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