A welding method for composite plate

Abstract

The present invention belongs to the field of welding engineering in the railway locomotive and rolling stock industry, and discloses a method for welding composite plates. The method comprises: S1: welding a carbon steel base layer and a stainless steel cladding layer into an integrated layered composite plate; S2: performing groove processing on the welding surface of one integrated layered composite plate, and providing a blunt edge on the carbon steel base layer side of the composite plate; symmetrically processing another integrated layered composite plate, so that the grooves of the two composite plates form a V-shaped groove after being paired; S3: mechanically cleaning and drying the composite plate processed in step S2; S4: pairing the grooves; S5: welding the carbon steel base layer; S6: welding the stainless steel cladding layer. In view of the characteristics of the ultra-thin cladding layer of the TE4003C5 composite plate, the present invention provides a method comprising performing groove processing on the welding surface of the composite plate and welding after pairing, thereby improving the welding quality and efficiency of the TE4003C5 composite steel plate.

Description

Technical Field

[0001] The present invention belongs to the field of welding engineering in the railway locomotive and vehicle industry, and more specifically, relates to a welding method for composite plates. Background Art

[0002] Railway freight cars are currently primarily constructed of Q450NQR1 weathering steel. After two maintenance cycles, these freight cars experience severe corrosion, impacting their operating costs and efficiency. Railway freight cars constructed of T4003 steel offer excellent corrosion resistance, far exceeding their 25-year design lifespan. However, their high material cost and low strength make them difficult to adapt to the growing demand for heavy-duty freight cars and hinder their widespread deployment. The development of new materials with high strength, high corrosion resistance, and low cost is an urgent need for the railway sector. To this end, TISCO has independently developed a new high-strength, corrosion-resistant stainless steel composite material, TE4003C5 (T4003 + Q450NQR1). This composite plate features a base layer of high-strength weathering steel Q450NQR1 and a cladding layer of ferritic stainless steel T4003. The composite material is welded and then rolled. The base layer primarily provides strength, stiffness, and toughness, while the cladding layer enhances corrosion resistance, achieving a perfect balance of high strength and corrosion resistance.

[0003] TE4003C5 is a new type of composite sheet material, with a stainless steel cladding layer only 0.5mm thick. Currently, no mature welding method is suitable for this material. The welding performance of the composite sheet is directly related to its application in railway freight cars. Due to the significant difference in thermal expansion coefficients between the ferritic stainless steel cladding layer and the carbon steel base layer, direct welding can lead to weak weld adhesion, easy delamination between the cladding and the base plate, and the formation of unfused defects. Furthermore, when welding TE4003C5 composite plates, the mutual dissolution of the dissimilar metals may form brittle and hard intermetallic compounds, increasing the tendency for weld cracking and seriously affecting the performance of the composite plate welded joint. Problems such as cracks and pores that arise during welding pose challenges to the application of TE4003C5 composite plates.

[0004] Therefore, how to improve the welding quality and welding efficiency of TE4003C5 composite steel plates while ensuring the performance of the composite plates has become an urgent problem that needs to be solved.

[0005] Existing welding techniques for composite plates typically utilize a "base + transition layer + cladding" welding method. To maintain the composite steel plate's inherent performance, the base and cladding layers must be welded separately, with the addition of a transition layer. The purpose of welding the transition layer is to compensate for the reduction in alloying elements (such as chromium and nickel) caused by dilution, maintaining the desired alloy composition of the composite weld. However, because the stainless steel cladding layer of TE4003C5 composite plates is only 0.5 mm thick, existing welding methods are unsuitable for this material.

[0006] Therefore, it is urgent to propose a new welding method for composite plates. Summary of the Invention

[0007] The present invention addresses the shortcomings of existing technologies and proposes a method for welding composite plates. This method, which addresses the characteristics of the ultra-thin coating of TE4003C5 composite plates, includes beveling the weld surfaces of the composite plates, assembling them, and then welding them together, thereby improving the welding quality and efficiency of the TE4003C5 composite steel plates.

[0008] In order to achieve the above object, the present invention provides a method for welding a composite plate, the method comprising the following steps:

[0009] S1: Obtaining a composite plate: welding a carbon steel base layer and a stainless steel cladding layer into an integrated layered composite plate;

[0010] S2: Beveling: Beveling the welded surface of one of the integrated layered composite plates, providing a blunt edge on the carbon steel base layer side of the composite plate; symmetrically processing another integrated layered composite plate, so that the grooves of the two composite plates form a V-shaped groove after being aligned;

[0011] S3: groove cleaning: mechanically clean and dry the composite board treated in step S2;

[0012] S4: groove pairing;

[0013] S5: carbon steel base welding;

[0014] S6: Stainless steel cladding welding.

[0015] According to the present invention, preferably, in step S1, the welding method is at least one of explosion welding, hot rolling composite method and brazing method.

[0016] According to the present invention, preferably, the thickness of the carbon steel base layer is 4.5-7.5 mm; the carbon steel base layer is at least one of high-strength weathering steel Q450NQR1, Q235A, Q235A and Q345B.

[0017] According to the present invention, preferably, the thickness of the stainless steel coating is 0.5-1 mm; the stainless steel coating is at least one of ferritic stainless steel T4003, austenitic stainless steel 1Cr18Ni9Ti, austenitic stainless steel 0Cr18Ni9 and austenitic stainless steel 0Cr19Ni9N.

[0018] According to the present invention, preferably, in step S2, the bevel processing angle of each of the integrated layered composite panels is 25°-30°, so that the bevels of the two composite panels are paired to form a V-shaped bevel of 50°-60°.

[0019] According to the present invention, preferably, in step S2, the thickness of the blunt edge is 1-2 mm.

[0020] According to the present invention, preferably, in step S3, the mechanical cleaning includes sequentially removing rust and oxide films, polishing, and removing grease, dirt, and impurities. In the present invention, as a preferred embodiment, stainless steel wire is used to remove the rust and oxide films on the surface of the composite plate to prevent cracks and pores during welding. The cleaning range includes the composite plate base layer, cladding, and the entire groove surface. The surface is then polished with coarse sandpaper and then with fine sandpaper until smooth. Finally, the composite plate is wiped with alcohol and acetone to remove grease, dirt, and impurities, and then blown dry.

[0021] In the present invention, the quality of the groove is checked before welding to ensure that the groove is well processed, and the groove is paired after the groove is cleaned. According to the present invention, preferably, in step S4, the gap range of the groove pair is 0-2mm.

[0022] According to the present invention, preferably, in step S5:

[0023] The welding method is MAG welding;

[0024] The welding wire used is at least one of TH550-NQ-II welding wire, ER50-6 welding wire, ER49-1 welding wire and H08MnSiCuCrNi-II welding wire;

[0025] The diameter of the welding wire is 1.0-1.6 mm, preferably 1.0 mm, 1.2 mm, or φ1.6 mm;

[0026] The welding current is 90-120A, and the welding arc voltage is 13-16V;

[0027] The welding speed is 120-130mm / min;

[0028] The shielding gas for welding is a mixture of Ar and CO2, wherein the content of Ar is 75-85% and the content of CO2 is 15-25% based on the total weight of the mixture of Ar and CO2;

[0029] Gas volume flow rate is 18-20L / min;

[0030] The weld of the carbon steel base is 1-1.5mm lower than the boundary between the carbon steel base and the stainless steel cladding, which is conducive to the welding operation and ensures that the base weld metal will not be welded to the stainless steel cladding, burning the cladding metal, thereby ensuring the welding quality.

[0031] In the present invention, the carbon steel base is welded using a low current and slow welding speed. This is because if the heat input is too high, the composite plate will easily generate large thermal stress during welding, which may cause cracks. If the heat input is too low, multiple layers of welding will be required when welding the base.

[0032] In the present invention, MAG welding has the advantages of low cost, low operating difficulty, mature technology, and good weld forming quality, so the base layer welding adopts the more mature MAG welding for the base welding.

[0033] According to the present invention, preferably, in step S6:

[0034] The welding method is MAG welding;

[0035] The welding wire used is ER309LSi-G welding wire and / or E308L-G welding wire;

[0036] The welding current is 180-200A, and the welding arc voltage is 18-20V;

[0037] The welding speed is 220-260mm / min;

[0038] The shielding gas for welding is a mixture of Ar and CO2, wherein the content of Ar is 95-98% and the content of CO2 is 2-5% based on the total weight of the mixture of Ar and CO2;

[0039] Gas volume flow rate is 18-20L / min;

[0040] The weld thickness of the stainless steel cladding is 1-2mm.

[0041] In the present invention, the cladding adopts high-current, fast welding specifications to increase welding speed while avoiding the formation of brittle and hard compounds, ensuring weld quality. The cladding weld thickness is 1-2mm, which not only ensures the Cr and Ni content in the weld and the corrosion resistance of the weld, but also prevents excessive Cr and Ni content and the formation of martensite.

[0042] In the present invention, after the stainless steel cladding is welded in step S6, the cladding side should be cleaned of slag and splashing adhesives on the weld surface using a stainless steel special tool.

[0043] The beneficial effects of the technical solution of the present invention are as follows:

[0044] This invention addresses the unique characteristics of ultra-thin cladding layers on TE4003C5 composite plates and the lack of welding methods, providing a novel "base + cladding" welding method. This method, specifically for TE4003C5 composite plates, includes beveling the weld surfaces of the composite plates. After assembly, the base and cladding layers are welded using the proven and easy-to-operate MAG welding method. The base layer is welded using low-current, slow-speed welding techniques to ensure root penetration. The cladding layer is welded using high-current, fast-speed welding techniques to cover the surface. This method controls the welding heat input to no more than 0.7 kJ / mm, effectively controlling the weld dilution rate and improving the welding quality and efficiency of the TE4003C5 composite steel plate.

[0045] The welding method of the present invention can ensure the smooth progress of the TE4003C5 composite plate welding process, solve the problems of low weld joint quality and poor weld formation, and enable the TE4003C5 composite plate material to be better promoted and applied on railway vehicles.

[0046] The present invention directly welds the cladding layer and the base layer during welding without the need for welding an intermediate transition layer, thereby simplifying the process and saving filling materials, thereby achieving efficient welding of the TE4003C5 composite plate.

[0047] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0049] Figure 1 A schematic diagram of a composite plate obtained in step S1 of a welding method for a composite plate provided in Example 1 of the present invention is shown.

[0050] Figure 2 A schematic diagram of groove processing in step S2 of a welding method for a composite plate provided in Example 1 of the present invention is shown.

[0051] Figure 3 A schematic diagram of welding in steps S5 and S6 of a composite plate welding method provided in Example 1 of the present invention is shown.

[0052] Figure 4 The figure shows the weld fracture condition of sample 2 of Example 2 in Test Example 1 of the present invention.

[0053] Figure 5 The figure shows the weld fracture condition of the sample 1 of Example 3 in Test Example 1 of the present invention.

[0054] Figure 6 The figure shows the fracture condition of the base material of the sample 1 of Example 1 in Test Example 1 of the present invention.

[0055] Figure 7 The figure shows the fracture condition of the weld of the sample of Example 3 in Test Example 2 of the present invention.

[0056] 8( a ) and ( b ) respectively show the situation in which some samples of Examples 1 and 2 in Test Example 2 of the present invention passed the bending test.

[0057] Figure 9 The hardness test area division diagram in Test Example 4 of the present invention is shown. (Where F represents the upper part of the sample and R represents the lower part of the sample)

[0058] The reference numerals are as follows:

[0059] 1-Weld; 2-Heat-affected zone; 3-Base material. DETAILED DESCRIPTION

[0060] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Instead, these embodiments are provided to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0061] Example 1

[0062] This embodiment provides a method for welding a composite plate, the method comprising the following steps:

[0063] S1: Obtaining a composite plate: A carbon steel base layer with a thickness of 5.5 mm and a stainless steel cladding layer with a thickness of 0.5 mm are explosively welded into an integrated layered composite plate. Figure 1 As shown; the carbon steel base layer is high-strength weathering steel Q450NQR1; the stainless steel cladding is ferritic stainless steel T4003.

[0064] S2: Beveling: Beveling is performed on the welding surface of the integrated layered composite plate, and a blunt edge is set on the carbon steel base side of the composite plate, such as Figure 2 As shown, the groove processing angle is 30°, and the thickness of the blunt edge is 2 mm; another one-piece layered structure composite plate is symmetrically processed so that the grooves of the two composite plates are matched to form a V-shaped groove with an angle of 60°;

[0065] S3: Groove cleaning: The composite plate treated in step S2 is mechanically cleaned and dried. Specifically, stainless steel wire is used to remove the rust layer and oxide film on the surface of the composite plate to prevent cracks and pores during welding. The cleaning range includes the composite plate base, covering layer and the entire groove surface. Then, it is polished with coarse sandpaper and then polished with fine sandpaper until smooth. Finally, the composite plate is wiped with alcohol and acetone to remove grease, dirt and impurities and then dried.

[0066] S4: groove pair; the gap range of the groove pair is 1mm, such as Figure 3 shown.

[0067] S5: carbon steel base welding;

[0068] The welding method is MAG welding;

[0069] The welding wire used is TH550-NQ-Ⅱ welding wire; the diameter of the welding wire is 1.2 mm;

[0070] The welding current is 95A and the welding arc voltage is 16V;

[0071] The welding speed is 125mm / min;

[0072] The shielding gas for welding is 80% Ar + 20% CO2;

[0073] The gas volume flow rate is 18L / min;

[0074] The weld of the carbon steel base is 1 mm lower than the boundary between the carbon steel base and the stainless steel cladding.

[0075] S6: Stainless steel cladding welding.

[0076] The welding method is MAG welding;

[0077] The welding wire used is ER309LSi-G welding wire; the diameter of the welding wire is 1.2 mm;

[0078] The welding current is 200A and the welding arc voltage is 20V;

[0079] The welding speed is 230 mm / min;

[0080] The shielding gas for welding is 97% Ar + 3% CO2;

[0081] The gas volume flow rate is 18L / min;

[0082] The weld thickness of the stainless steel cladding is 2mm.

[0083] After the stainless steel cladding is welded in step S6, the cladding side is cleaned of slag and spatter adhesives on the weld surface using a stainless steel special tool.

[0084] Example 2

[0085] The difference between this embodiment and embodiment 1 lies in the following parameters:

[0086] S5:

[0087] The welding current is 110A and the welding arc voltage is 16V;

[0088] The welding speed is 140mm / min;

[0089] S6:

[0090] The welding current is 230A and the welding arc voltage is 23V;

[0091] The welding speed is 275 mm / min.

[0092] Example 3

[0093] The difference between this embodiment and embodiment 1 is that TH550-NQ-II welding wire is used for welding the carbon steel base layer and the stainless steel cladding layer, and the welding wire is TH550NQ-II (covering) + TH550NQ-II (base).

[0094] S5:

[0095] The welding current is 90A and the welding arc voltage is 15V;

[0096] The welding speed is 96mm / min;

[0097] S6:

[0098] The welding current is 195A and the welding arc voltage is 21V;

[0099] The welding speed is 234 mm / min.

[0100] Test Example 1

[0101] In this test example, the TE4003C5 composite plate obtained in Examples 1-3 was subjected to a tensile test. The test method was GB / 2651, the temperature was 20°C, and the required value was ≥550 (N / mm 2 ).

[0102] The results are shown in Table 1. The two samples of Example 1 were obtained under the preparation conditions of Example 1, and the two samples of Example 2 were obtained under the preparation conditions of Example 2. The parent material refers to the part of the TE4003C5 composite plate except for the part welded with the welding wire.

[0103] Figure 4 This is a diagram showing the weld fracture of sample 2 in Example 2. Figure 5This figure shows the weld fracture of Sample 1 in Example 3. The standard values ​​for the tensile test in this test example are: 350 MPa for yield strength and 544 MPa for tensile strength. The yield strength and tensile strength of Sample 1 in Example 3 both exceeded the standard requirements. However, the fractures in Samples 2 and 3 in Example 2 occurred in the weld, indicating that the mechanical properties of the weld were inferior to those of the base material. Therefore, the test results of Samples 2 and 3 in Example 2 failed.

[0104] Table 1

[0105]

[0106] Test Example 2

[0107] In this test example, the TE4003C5 composite board obtained in Examples 1-3 was subjected to a bending test with a bending angle of 180° and an indenter diameter of 40 mm. Test standard: a defect less than 3 mm long on the curved surface of the specimen shall be considered qualified (reference standard is GB / 2653).

[0108] In this test example, four samples obtained under the preparation conditions of Example 1, four samples obtained under the preparation conditions of Example 2, and one sample of Example 3 were tested.

[0109] The test results are as follows: All four samples of Example 1 and four samples of Example 2 are qualified, as shown in Figure 8 (a) and (b). Figure 6 It can be seen that fracture occurred in the weld area and the test results failed.

[0110] Test Example 3

[0111] In this test example, the TE4003C5 composite board obtained in Examples 1-3 was subjected to an impact test. The test method was GB / 2650, category: V; sample size (mm): 5*10*55; required value: ≥30J;

[0112] The results are shown in Table 2. The parent material refers to the part of the TE4003C5 composite plate except the part welded with welding wire.

[0113] Table 2

[0114]

[0115] Test Example 4

[0116] In this test example, the hardness test of the TE4003C5 composite plate obtained in Example 1-2 was carried out according to the test method GB / T2654, HV10. Figure 7As shown, this test example tests three areas of the TE4003C5 composite plate obtained in Examples 1-2, including the base material 3, the heat-affected zone 2, and the weld 1. The base material 3 and the heat-affected zone 2 also include the left and right areas of the weld, namely, area ① and area ②. Each area is tested three times (corresponding to Figure 7 The results are shown in Table 3.

[0117] Table 3

[0118]

[0119] The results of Test Examples 1-4 indicate that, compared to Example 1, Example 2 utilizes higher welding current and voltage values, resulting in greater heat input, during stainless steel cladding welding. Consequently, the weld hardness of Example 2 is greater than that of Example 1, while the impact toughness is lower. Furthermore, during the tensile test, some specimens fractured along the weld, which is unacceptable. Therefore, Example 2 is not as effective as Example 1.

[0120] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for welding a composite plate, characterized in that: The method consists of the following steps: S1: Obtaining a composite plate: welding a carbon steel base layer and a stainless steel cladding layer into an integrated layered composite plate; The carbon steel base layer is high-strength weathering steel Q450NQR1; The thickness of the stainless steel coating is 0.5-1 mm; the stainless steel coating is ferritic stainless steel T4003; S2: Beveling: Beveling the welded surface of one of the integrated layered composite plates, providing a blunt edge on the carbon steel base layer side of the composite plate; symmetrically processing another integrated layered composite plate, so that the grooves of the two composite plates form a V-shaped groove after being aligned; S3: groove cleaning: mechanically clean and dry the composite board treated in step S2; S4: groove pairing; S5: carbon steel base welding; In step S5: The welding method is MAG welding; The welding wire used is at least one of TH550-NQ-II welding wire, ER50-6 welding wire, ER49-1 welding wire and H08MnSiCuCrNi-II welding wire; The diameter of the welding wire is 1.0-1.6 mm; The welding current is 90-120A, and the welding arc voltage is 13-16V; The welding speed is 120-130mm / min; The shielding gas for welding is a mixture of Ar and CO2, wherein the content of Ar is 75-85% and the content of CO2 is 15-25% based on the total weight of the mixture of Ar and CO2; Gas volume flow rate is 18-20L / min; The weld of carbon steel base is 1-1.5mm lower than the boundary between carbon steel base and stainless steel cladding; S6: stainless steel cladding welding; In step S6: The welding method is MAG welding; The welding wire used is ER309LSi-G welding wire and / or E308L-G welding wire; The diameter of the welding wire is 1.0-1.6 mm; The welding current is 180-200A, and the welding arc voltage is 18-20V; The welding speed is 220-260mm / min; The shielding gas for welding is a mixture of Ar and CO2, wherein the content of Ar is 95-98% and the content of CO2 is 2-5% based on the total weight of the mixture of Ar and CO2; Gas volume flow rate is 18-20L / min; The weld thickness of the stainless steel cladding is 1-2mm.

2. The welding method of the composite plate according to claim 1, wherein: In step S1 , the welding method is at least one of explosion welding, hot rolling composite method and brazing method.

3. The welding method of composite plate according to claim 1, wherein: The thickness of the carbon steel base layer is 4.5-7.5 mm.

4. The welding method of composite plate according to claim 1, wherein: In step S2, the bevel processing angle of each of the integrated layered composite panels is 25°-30°.

5. The welding method of composite plate according to claim 1, wherein: In step S2, the thickness of the blunt edge is 1-2 mm.

6. The welding method of composite plate according to claim 1, wherein: In step S3, the mechanical cleaning includes a process of removing rust and oxide film, a polishing process, and a process of removing grease, dirt and impurities in sequence.

7. The welding method of composite plate according to claim 1, wherein: In step S4, the gap between the groove pairs is in the range of 0-2 mm.

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