Composite stainless steel plate and welding method thereof

Abstract

The invention provides a composite stainless steel plate and a welding method thereof. A base layer of the composite stainless steel plate is FH500 low-temperature high-strength steel, and a composite layer of the composite stainless steel plate is 317L corrosion-resistant stainless steel. The welding method comprises the steps of groove machining, groove cleaning, plate combination, base layer welding on the multi-layer side, base layer welding on the back face, transition layer welding and multi-layer welding. According to the welding method of the composite stainless steel plate, through groove structure optimization, step-by-step welding sequence design and corresponding process parameter matching, the problem of welding defects caused by material heterogeneity of the FH500 + 317L composite steel plate is systematically solved, the performance of a welded joint is improved, manufacturing of the high-strength, high-toughness and corrosion-resistant welded joint is achieved, and the production cost is reduced. The blank of the low-temperature high-strength steel and the 317L composite steel plate in the ship application field is filled, the welding quality and welding efficiency of the composite steel plate are improved, and the construction efficiency and economic benefits are remarkably improved.

Description

Technical Field

[0001] This application belongs to the technical field of shipbuilding, and particularly relates to a composite stainless steel plate and its welding method. Background Art

[0002] With the evolution of the global strategic pattern, the polar region, as an important area for global strategic development, has attracted great attention from the international community for its scientific research value and resource reserves. It is worth noting that compared with traditional shipping lanes, polar shipping lanes can significantly shorten the shipping mileage by 30%-40%, with significant economic benefits. Against this background, the research and development of polar navigation ships has become an important topic in the global scientific and technological and economic development.

[0003] In the prior art, the international shipbuilding industry has gradually adopted composite steel plates as key structural materials for polar ships. For example, stainless steel composite steel plates have been applied in the ice belt area of Russian heavy icebreakers, and similar composite materials are also used in the design of newly built icebreakers in European and American countries. However, the industrial application of this material has not been realized in the polar icebreakers currently in service in China. At present, stainless steel composite plates for polar regions usually adopt a bimetallic composite structure, with 317L austenitic stainless steel as the clad layer and FH500 low-temperature high-strength steel as the base layer, and metallurgical bonding is achieved through explosive welding or hot rolling composite process. This structural design not only maintains the corrosion resistance of the stainless steel layer but also makes full use of the mechanical properties and low-temperature toughness of the high-strength steel in the base layer, effectively reducing the ship maintenance cost in the harsh polar environment. However, due to the significant differences in physical and chemical parameters such as the coefficient of thermal expansion (CTE difference up to 25%), thermal conductivity (difference of about 3 times), and phase transformation characteristics between the base layer and the clad layer materials, there are certain difficulties in welding the composite steel plate in actual applications. Defects such as interface peeling and low-temperature cracks are easily generated during the welding process, which cannot guarantee the quality and welding efficiency of the composite plate weld seam, seriously restricting its industrial application process.

[0004] Therefore, it is necessary to develop a low-temperature high-strength composite stainless steel plate for polar icebreakers and its welding method. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of this application is to provide a composite stainless steel plate and its welding method to improve the weld quality and welding efficiency of the composite plate of the ship, so as to ensure the service life and navigation safety of the ship in the polar state.

[0006] In the first aspect, this application provides a composite stainless steel plate and its welding method, which at least includes the following steps:

[0007] S1: Process the groove of the composite plate to be welded into an X shape. The groove includes a first groove on the clad layer side and a second groove on the base layer side, and the angle of the first groove is smaller than the angle of the second groove;

[0008] S2: Grind the areas on both sides of the groove of the composite plate to be welded. After grinding the cladding and the base layer separately, butt and position the two plates.

[0009] S3: Carry out the welding process in sequence to obtain the composite plate product. The welding sequence is: welding the base layer on the cladding side, welding the base layer on the back, welding the transition layer, and welding the cladding.

[0010] In an alternative embodiment, in step S1,

[0011] The angle of the first groove on the cladding side is 50 degrees to 70 degrees.

[0012] The angle of the second groove on the base layer side is 80 degrees to 100 degrees.

[0013] In an alternative embodiment, in step S1, a root face is provided between the first groove and the second groove. Both ends of the root face extend to the bottom surfaces of the first groove and the second groove respectively, and the length of the root face is 0 to 2 mm.

[0014] In an alternative embodiment, in step S1, there is a gap on both sides of the root of the first groove and the second groove, and the gap is 0 to 2 mm.

[0015] In an alternative embodiment, in step S2, the grinding range on both sides of the groove extends 20 mm from the groove to both sides.

[0016] In an alternative embodiment, the composite stainless steel plate includes a base layer and a cladding. The base layer is FH500 steel, the cladding is 317L stainless steel, and the thickness of the composite stainless steel plate is 51 mm to 56 mm.

[0017] In an alternative embodiment, in step S3, for the welding of the base layer, the SAW welding process is adopted. Before welding, place the composite plate to be welded in an oven at 300 °C to 400 °C for baking for 1 h to 3 h. During welding, the welding current is 530 A to 550 A, the welding voltage is 29 V to 31 V, and the welding speed is 40 cm / min to 43 cm / min.

[0018] In an alternative embodiment, in step S3, for the welding of the base layer, the FCAW welding process is adopted. The selected wire diameter is 1.2 mm, and the shielding gas is 80% Ar / 20% CO 2 , and during welding, the welding current is 220 A to 230 A, the welding voltage is 25 V to 27 V, and the welding speed is 25 cm / min to 40 cm / min.

[0019] In an alternative embodiment, in step S3, for the welding of the cladding layer, the GMAW welding process is adopted, the selected wire diameter is 1.0 mm, and the shielding gas is 97.5% Ar / 2.5% CO 2 , during welding, the welding current is 220 A to 240 A, the welding voltage is 24 V to 26 V, and the welding speed is 24 cm / min to 40 cm / min.

[0020] In a second aspect, the present application provides a composite stainless steel plate, which is processed by the welding method provided by the above technical solution.

[0021] Compared with the prior art, the technical solution provided by the present application has the following beneficial effects:

[0022] The welding method of the composite stainless steel plate provided by the present application systematically solves the welding defect problem caused by material heterogeneity of the FH500 + 317L composite steel plate through groove structure optimization, step-by-step welding sequence design and corresponding process parameter matching, improves the performance of the welded joint, realizes the manufacture of high-strength, high-toughness and corrosion-resistant welded joints, fills the gap in the application field of low-temperature high-strength steel and 317L composite steel plates in ships, improves the welding quality and welding efficiency of the composite steel plate, and significantly improves the construction efficiency and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It shows a schematic diagram of the groove structure of the composite stainless steel plate;

[0024] Figure 2 It shows a schematic diagram of the bead arrangement of the composite stainless steel plate;

[0025] Figure 3 It shows the surface morphology of the weld on the base layer side of the composite stainless steel plate;

[0026] Figure 4 It shows the surface morphology of the weld on the cladding layer side of the composite stainless steel plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following specific examples illustrate the embodiments of the present application. Those skilled in the art can easily understand other advantages and principles of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application.

[0028] The present application provides a welding method for composite stainless steel plates, which is applicable to the field of welding stainless steel composite plates for polar ships and polar equipment. The composite stainless steel plate is made by explosion welding or rolling. The base layer of the composite plate is FH500 low-temperature high-strength steel, and the clad layer is 317L corrosion-resistant stainless steel. The welding method involved in the technical solution of the present application generally includes the following steps: groove machining, groove cleaning and plate combination, welding of the base layer on the clad layer side, welding of the base layer on the back side, welding of the transition layer, and welding of the clad layer. Using the welding method provided by the present application can avoid the appearance of brittle and crack-prone structures in the composite plate during welding, prevent welding cracks, and thus improve the welding quality and welding efficiency of the composite stainless steel plate.

[0029] Example 1:

[0030] See Figures 1 to 4 , this embodiment provides a welding method for a composite stainless steel plate. The composite stainless steel plate used for welding includes a base layer and a clad layer. The base layer of the composite steel plate in this embodiment is FH500 with a thickness of 48 mm, and the clad layer is 317L stainless steel with a thickness of 6 mm. Its welding method includes the following steps:

[0031] S1: Groove machining.

[0032] Specifically, the groove of the composite plate to be welded is processed into an X shape. The groove includes a first groove 100 on the clad layer side and a second groove 200 on the base layer side. The angle of the first groove 100 is smaller than the angle of the second groove 200. Among them, the small-angle groove on the clad layer reduces the sensitization effect of heat input on the stainless steel, and the large-angle groove on the base layer increases the molten pool filling space, and the root lack of penetration rate is reduced to ≤1%, far lower than 5%-8% of the traditional V-shaped groove.

[0033] Optionally, the depth of the second groove 200 is h, the thickness of the base layer is t1, and the thickness of the clad layer is t2, where h ≤ 1 / 3t1.

[0034] Optionally, the machining process is selected for groove machining. The groove dimension accuracy is controlled within ±0.1 mm to ensure the consistency of the weld seam; the surface roughness Ra of the groove ≤ 6.3 μm, which can significantly reduce the risk of slag inclusion.

[0035] Optionally, the angle of the first groove 100 on the clad layer side is 50 degrees to 70 degrees; the angle of the second groove 200 on the base layer side is 80 degrees to 100 degrees. Further, when the groove angle of the clad layer is less than 50°, the penetration is insufficient and full penetration cannot be achieved; when it is greater than 70°, the heat input is too large and the clad layer is sensitized. Therefore, the angle of the first groove 100 on the clad layer side is 60 ± 1 degree; the angle of the second groove 200 on the base layer side is 90 ± 1 degree

[0036] Optionally, a root face 300 is provided between the first groove 100 and the second groove 200. Both ends of the root face 300 extend to the bottom surfaces of the first groove 100 and the second groove 200 respectively. The length of the root face 300 is 0 - 2 mm. The root face 300 can limit the fluctuation of the penetration depth and avoid burn-through or lack of fusion. Further, the length of the root face 300 is 2 mm.

[0037] Optionally, there is a gap on both sides of the root of the first groove 100 and the second groove 200. The distance of this gap is 0 - 2 mm, which is used to optimize the molten pool flow and reduce the porosity. Further, the distance of this gap is 2 mm.

[0038] S2: Groove cleaning and plate combination.

[0039] Specifically, the areas on both sides of the groove of the composite plate to be welded are ground. After the cladding layer and the base layer are ground respectively, the two plates are butt - jointed and positioned.

[0040] Optionally, the grinding range on both sides of the groove is the area extending 20 mm from the groove to both sides. The grinding method uses a grinding wheel machine. Then, it is wiped and cleaned with alcohol. The grinding wheel for the cladding layer of stainless steel and the base layer shall not be used interchangeably to avoid contaminating the cladding layer with carbon steel particles, reducing inclusions, and preventing local corrosion of stainless steel. Groove cleaning can remove the oxide layer and oil stain. The residual amount of oil stain ≤ 50 mg / m 2 , improving the fusion quality; after cleaning with alcohol, the surface oxygen content ≤ 200 ppm, which well inhibits the generation of pores during welding.

[0041] S3: Carry out the welding process in sequence to obtain the composite plate product; the welding sequence is: the base layer welding on the cladding layer side, the base layer welding on the back, the transition layer welding, and the cladding layer welding. As Figure 2 shown, the serial numbers 1 - 49 are the welding sequence: serial numbers 1 - 12 are the base layer welding on the cladding layer side, serial numbers 13 - 33 are the base layer welding on the back, serial numbers 34 - 40 are the transition layer welding, and serial numbers 41 - 49 are the cladding layer welding. Compared with the welding method using the traditional sequence (base layer → cladding layer), the incidence rate of interface cracks of the welding method provided in this embodiment can be reduced to less than 1%.

[0042] Optionally, the SAW welding process is used for welding the base layer, and the root dimension is appropriately reduced to reduce the machining amount of the back carbon gouging. A 4.0mm Ni 1K welding wire and 8500 welding flux are selected. The alkalinity of the 8500 welding flux can reduce the sensitivity to hydrogen-induced cracking. Before welding, the composite plate to be welded is placed in an oven at 300°C to 400°C for baking for 1h to 3h, and the preheating temperature is set to avoid the sensitization range of stainless steel, such as 300°C, 350°C, 380°C or 400°C. During welding, the welding current is 530A to 550A, the welding voltage is 29V to 31V, and the welding speed is 40cm / min to 43cm / min. Further, the baking parameters before welding are set to bake at 300°C for 2 hours.

[0043] Optionally, the GMAW welding process is used for welding the clad layer. The selected welding wire is A940 with a diameter of 1.0mm, and the shielding gas is 97.5% Ar / 2.5% CO 2 , during welding, the welding current is 220A to 240A, the welding voltage is 24V to 26V, and the welding speed is 24cm / min to 40cm / min. To prevent the molten droplets from splashing onto the clad layer groove during welding of the base layer, the vicinity of the clad layer groove needs to be isolated with aluminum foil during welding of the base layer. The thermal expansion coefficients of the low alloy steel of the base layer and the stainless steel of the clad layer differ greatly. To avoid delamination and cracking at the explosion welding interface caused by heat accumulation during welding, the inter-pass temperature of the base layer welding is also controlled between 80°C and 100°C.

[0044] Example Two:

[0045] See Figures 1 to 4 , this example also provides a welding method for a composite stainless steel plate. The composite stainless steel plate used for welding includes a base layer and a clad layer. The base layer of the composite steel plate in this example is FH500 with a thickness of 44mm, and the clad layer is 317L stainless steel with a thickness of 8mm. The welding method includes the following steps:

[0046] S1: Groove machining.

[0047] Specifically, the groove of the composite plate to be welded is machined into an X shape. The groove includes a first groove 100 on the clad layer side and a second groove 200 on the base layer side. The angle of the first groove 100 is smaller than the angle of the second groove 200.

[0048] Optionally, the machining process is selected for groove machining.

[0049] Optionally, the angle of the first groove 100 on the clad layer side is 50 degrees to 70 degrees; the angle of the second groove 200 on the base layer side is 80 degrees to 100 degrees. Further, the angle of the first groove 100 on the clad layer side is 50±1 degree; the angle of the second groove 200 on the base layer side is 80±1 degree.

[0050] Optionally, a root face 300 is provided between the first groove 100 and the second groove 200. Both ends of the root face 300 extend to the bottom surfaces of the first groove 100 and the second groove 200 respectively, and the length of the root face 300 is 0 - 2 mm. Further, the length of the root face 300 is 1 mm.

[0051] Optionally, there is a gap on both sides of the root of the first groove 100 and the second groove 200, and the distance of this gap is 0 - 2 mm. Further, the distance of this gap is 0 mm.

[0052] S2: Groove cleaning and plate combination.

[0053] Specifically, the areas on both sides of the groove of the composite plate to be welded are polished. After the cladding layer and the base layer are polished separately, the two plates are butt - jointed and positioned.

[0054] Optionally, the polishing range on both sides of the groove extends 20 mm from the groove to both sides. The polishing method uses a grinding wheel machine for polishing, and then it is wiped and cleaned with alcohol. The grinding wheel for polishing the cladding layer of stainless steel and the base layer shall not be mixed.

[0055] S3: Carry out the welding process in sequence to obtain the composite plate product; the welding sequence is: the base layer welding on the cladding layer side, the base layer welding on the back, the transition layer welding, and the cladding layer welding. As Figure 2 shown, the serial numbers 1 - 49 are the welding sequence: serial numbers 1 - 12 are the base layer welding on the cladding layer side, serial numbers 13 - 33 are the base layer welding on the back, serial numbers 34 - 40 are the transition layer welding, and serial numbers 41 - 49 are the cladding layer welding.

[0056] Optionally, the base layer welding adopts the FCAW welding process. The selected wire diameter is 1.2 mm, and the shielding gas is 80% Ar / 20% CO 2 , during welding, the welding current is 220 A - 230 A, the welding voltage is 25 V - 27 V, and the welding speed is 25 cm / min - 40 cm / min.

[0057] Optionally, the cladding layer welding adopts the GMAW welding process. The selected wire is A940 wire with a diameter of 1.0 mm, and the shielding gas is 97.5% Ar / 2.5% CO 2 , during welding, the welding current is 220 A - 240 A, the welding voltage is 24 V - 26 V, and the welding speed is 24 cm / min - 40 cm / min. To prevent the molten droplets from splashing to the cladding layer groove during the base layer welding, the cladding layer groove should be isolated with aluminum foil paper during the base layer welding. The thermal expansion coefficients of the base layer low - alloy steel and the cladding layer stainless steel differ greatly. To avoid the delamination and cracking of the explosion - welded interface caused by the heat accumulation during the welding process, the inter - pass temperature of the base layer welding is also controlled between 80°C and 100°C.

[0058] Example 3:

[0059] Refer to Figures 1 to 4 , this example also provides a welding method for a composite stainless steel plate. The composite stainless steel plate to be welded includes a base layer and a clad layer. The base layer of the composite steel plate in this example is FH500 with a thickness of 47 mm, and the clad layer is 317L stainless steel with a thickness of 4 mm. The welding method includes the following steps:

[0060] S1: Groove machining.

[0061] Specifically, the groove of the composite plate to be welded is processed into an X shape. The groove includes a first groove 100 on the clad layer side and a second groove 200 on the base layer side. The angle of the first groove 100 is smaller than the angle of the second groove 200.

[0062] Optionally, the machining method of the groove is selected as a machining process.

[0063] Optionally, the angle of the first groove 100 on the clad layer side is 50 degrees to 70 degrees; the angle of the second groove 200 on the base layer side is 80 degrees to 100 degrees. Further, the angle of the first groove 100 on the clad layer side is 70 ± 1 degree; the angle of the second groove 200 on the base layer side is 100 ± 1 degree.

[0064] Optionally, a root face 300 is provided between the first groove 100 and the second groove 200. Both ends of the root face 300 extend to the bottom surfaces of the first groove 100 and the second groove 200 respectively. The length of the root face 300 is 0 to 2 mm. Further, the length of the root face 300 is greater than 0.

[0065] Optionally, there is a gap on both sides of the root of the first groove 100 and the second groove 200. The distance of this gap is 0 to 2 mm. Further, the distance of this gap is 1 mm.

[0066] S2: Groove cleaning and plate combination.

[0067] Specifically, the areas on both sides of the groove of the composite plate to be welded are ground. After the clad layer and the base layer are ground respectively, the two plates are butted and positioned.

[0068] Optionally, the grinding range on both sides of the groove extends 20 mm from the groove to both sides. The grinding method is grinding with a grinding wheel. Then, it is wiped and cleaned with alcohol. The grinding wheel for the clad stainless steel and the base layer shall not be mixed.

[0069] S3: Carry out the welding process in sequence to obtain a composite plate product; the welding sequence is: welding of the base layer on the clad layer side, welding of the base layer on the back, welding of the transition layer, and welding of the clad layer. As Figure 2As shown, the serial numbers 1 - 49 are the welding sequence: serial numbers 1 - 12 are the base layer welding on the clad layer side, serial numbers 13 - 33 are the back base layer welding, serial numbers 34 - 40 are the transition layer welding, and serial numbers 41 - 49 are the clad layer welding.

[0070] Optionally, the SAW welding process is used for the welding of the base layer, and the root opening size is appropriately reduced to reduce the machining amount of the back carbon gouging. A 4.0mm Ni 1K welding wire and 8500 flux are selected. Before welding, the composite plate to be welded is baked at 300°C - 400°C for 1h - 3h, such as 300°C, 350°C, 380°C or 400°C. During welding, the welding current is 530A - 550A, the welding voltage is 29V - 31V, and the welding speed is 40cm / min - 43cm / min. Further, the baking parameters before welding are set to bake at 400°C for 2 hours.

[0071] Optionally, the GMAW welding process is used for the welding of the clad layer. The selected welding wire is A940 with a diameter of 1.0mm, and the shielding gas is 97.5% Ar / 2.5% CO 2 , during welding, the welding current is 220A - 240A, the welding voltage is 24V - 26V, and the welding speed is 24cm / min - 40cm / min. To prevent the molten droplets from splashing onto the clad layer groove during the welding of the base layer, the vicinity of the clad layer groove needs to be isolated with aluminum foil during the welding of the base layer. The thermal expansion coefficients of the base layer low alloy steel and the clad layer stainless steel differ greatly. To avoid the delamination and cracking of the explosion welding interface caused by the heat accumulation during the welding process, the interpass temperature of the base layer welding is also controlled between 80°C and 100°C.

[0072] According to the relevant regulations of the "Materials and Welding Code" of the China Classification Society, tensile tests, side bend tests, and -60°C Charpy V-notch impact tests are respectively carried out on Example 1, Example 2, and Example 3. The test results are shown in the following table. The tensile strength of the welded joints in each example meets the requirements, and the cracks after bending are all less than 3mm of the classification society specification. The low-temperature impact energy at different plate thickness positions is above 98J, indicating that the impact toughness of each example is good. The test results show that the welded joints obtained by the welding method of the composite stainless steel plate provided in this application have high strength, good plasticity, and impact toughness, and the implementation effect of the welding method provided in this application is good. Therefore, the technical solution provided in this application has high industrial utilization value because it effectively overcomes various disadvantages in the prior art.

[0073]

[0074]

[0075] The above embodiments are only illustrative of the principles and effects of the present application and are not intended to limit the present application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present application should still be covered by the claims of the present application.

Claims

1. A welding method for a composite stainless steel plate, characterized in that: At least the following steps are included: S1: Processing the groove of the composite plate to be welded into an X shape, wherein the groove includes a first groove located on the composite layer side and a second groove located on the base layer side, wherein the angle of the first groove is smaller than the angle of the second groove; S2: Grind the areas on both sides of the groove of the composite plate to be welded, and after the composite layer and the base layer are polished separately, the two plates are butt-jointed and positioned; S3: Perform welding processes in sequence to obtain a composite sheet product; the welding sequence is: base layer welding on the composite layer side, base layer welding on the back side, transition layer welding, and composite layer welding.

2. The welding method of the composite stainless steel plate according to claim 1, characterized in that: In step S1, the angle of the first groove on the composite layer side is 50 degrees to 70 degrees; The angle of the second groove on the base layer side is 80 to 100 degrees.

3. The welding method of composite stainless steel plate according to claim 1, characterized in that: In step S1, a blunt edge is provided between the first groove and the second groove, two ends of the blunt edge extend to the bottom surfaces of the first groove and the second groove respectively, and the length of the blunt edge is 0-2 mm.

4. The welding method of composite stainless steel plate according to claim 1, characterized in that: In step S1, there is a gap on both sides of the root of the first groove and the second groove, and the distance of the gap is 0-2 mm.

5. The welding method of composite stainless steel plate according to claim 1, characterized in that: In step S2, the grinding range on both sides of the groove is an area extending 20 mm from the groove to both sides.

6. The welding method of composite stainless steel plate according to claim 1, characterized in that: The composite stainless steel plate comprises a base layer and a composite layer, the base layer is FH500 steel, the composite layer is 317L stainless steel, and the thickness of the composite stainless steel plate is 51 mm to 56 mm.

7. The welding method of composite stainless steel plate according to claim 1, characterized in that: In step S3, the SAW welding process is used for the welding of the base layer. Before welding, the composite plate to be welded is placed at 300℃~400℃ and baked for 1h~3h. The welding current during welding is 530A~550A, the welding voltage is 29V~31V, and the welding speed is 40cm / min~43cm / min.

8. The welding method of composite stainless steel plate according to claim 1, characterized in that: In step S3, the FCAW welding process is adopted for the welding of the base layer, the selected welding wire diameter is 1.2mm, the shielding gas is 80% Ar / 20% CO2, the welding current is 220A~230A, the welding voltage is 25V~27V, and the welding speed is 25cm / min~40cm / min.

9. The welding method of composite stainless steel plate according to claim 1, characterized in that: In step S3, the GMAW welding process is adopted for welding the composite layer, the diameter of the selected welding wire is 1.0 mm, the shielding gas is 97.5% Ar / 2.5% CO2, the welding current is 220A-240A, the welding voltage is 24V-26V, and the welding speed is 24cm / min-40cm / min.

10. A composite stainless steel plate, characterized in that: The composite stainless steel plate is obtained by using the welding method described in any one of claims 1 to 9.

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