A welding method for optimizing the interfacial microstructure of stainless steel composite plate joints

Abstract

This invention discloses a welding method for optimizing the interfacial microstructure of a stainless steel composite plate joint. The stainless steel composite plate includes a substrate layer and a stainless steel cladding layer, with a transition layer at the interface between the substrate layer and the stainless steel cladding layer. The welding method includes the following steps: machining a V-groove on the welding section of the stainless steel composite plate and setting a blunt edge at the bottom of the V-groove; welding the substrate layer using single tungsten inert gas (TIG) welding; welding the transition layer using TIG welding; and welding the stainless steel cladding layer using TIG welding. This method can effectively control the width and hardening degree of the hard and brittle micro-regions at the welding interface between the transition layer and the substrate layer in the substrate-transition-cladding layer welding sequence, effectively improving the bonding performance of the interface. Simultaneously, it can ensure that the dilution rate of the cladding layer is controlled at an extremely low level, ensuring a reliable connection of the stainless steel composite plate.

Description

Technical Field

[0001] This invention relates to a welding method, and more particularly to a welding method for composite plates. Background Technology

[0002] Stainless steel composite plates generally refer to binary metal structural materials made by combining carbon steel and stainless steel through rolling, explosive bonding, and other methods. They possess good mechanical properties as well as functional requirements such as corrosion resistance and aesthetics.

[0003] Because the composition and physical properties of the two component metals, stainless steel and carbon steel, differ significantly, multi-layer and multi-pass welding should be used when welding stainless steel composite plates in engineering. This means that the joint weld is divided into a cladding stainless steel weld, a transition stainless steel weld, and a base carbon steel weld, and each layer is welded separately.

[0004] This raises the question of the welding sequence for the cladding layer, transition layer, and base layer. In engineering, the welding sequence of base layer-transition layer-cladding layer is the most commonly used because it is easier for construction workers to perform welding operations under this sequence, and the mechanical properties of carbon steel and the corrosion resistance of the cladding layer are easier to guarantee. This welding sequence is also the welding sequence recommended in the national standard GB / T13148-2008 "Technical Requirements for Welding of Stainless Steel Composite Plates".

[0005] However, for the welding of stainless steel composite plates in the sequence of base layer-transition layer-cladding layer, the key points for joint quality control, in addition to the control of the dilution rate of the cladding layer stainless steel weld, also include the interface control between the transition layer and the base layer.

[0006] Because the transition layer, cladding layer, and carbon steel base layer each require stainless steel and carbon steel welding materials that match the base metals during the welding process, the welding process between the transition layer and the carbon steel weld is essentially a dissimilar metal connection between stainless steel and carbon steel. Inevitably, a transition-hardened micro-region with martensite as the main structure will be generated at the interface. Excessive width and hardening of this micro-region can lead to severe non-uniform plastic deformation of the interface area under load, increasing the risk of cracking failure. Therefore, if this area is not controlled, it poses a service safety hazard to the joint. Summary of the Invention

[0007] The purpose of this invention is to provide a welding method for optimizing the interfacial microstructure of stainless steel composite plate joints. This method, based on a V-groove and employing single tungsten inert gas (TIG) welding, effectively controls the width and hardening degree of the hard and brittle micro-regions at the welding interface between the transition layer and the substrate layer in the substrate-transition layer-stainless steel cladding layer welding sequence. Simultaneously, it keeps the dilution rate of the stainless steel cladding layer extremely low. While ensuring the corrosion resistance requirements of the stainless steel cladding layer, it effectively improves the bonding performance of the interface, achieving a reliable connection of stainless steel composite plates in the substrate-transition layer-stainless steel cladding layer welding sequence.

[0008] To achieve the above objectives, the present invention provides a welding method for optimizing the interfacial structure of a stainless steel composite plate joint. The stainless steel composite plate includes a substrate layer and a stainless steel cladding layer, wherein a transition layer is provided at the interface between the substrate layer and the stainless steel cladding layer. The welding method includes the following steps:

[0009] A V-groove is machined on the welding section of the stainless steel composite plate, and a blunt edge is set at the bottom of the V-groove.

[0010] The substrate layer is welded using single tungsten inert gas welding;

[0011] The transition layer was welded using single tungsten inert gas welding;

[0012] The stainless steel composite layer was welded using single tungsten inert gas welding.

[0013] Furthermore, in the welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention, the angle α between the inclined portion of the V-groove and the vertical direction is ≥ (1.5b1)°, where b1 represents the distance from the surface of the substrate layer to its interface with the stainless steel composite layer, and its unit parameter is mm.

[0014] Furthermore, in the welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention, the thickness of the blunt edge b3 is 1-3 mm.

[0015] Furthermore, in the welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention, the assembly gap w2 of the V-groove is 1-3 mm.

[0016] In this implementation, the above process design can effectively reduce the operational difficulty of single tungsten inert gas welding.

[0017] Furthermore, in the welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention, in the step of welding the substrate layer using single tungsten inert gas welding: a solid carbon steel welding wire matching the substrate layer is used, and pure argon gas (e.g., with a purity of not less than 99%) is used for protection.

[0018] Furthermore, in the welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention, in the step of welding the substrate layer using single tungsten inert gas welding: the welding voltage is controlled at 13-16V, the welding current at 220-280A, the welding speed at 100-150mm / min, and the wire feed speed at 2.4-2.8m / min.

[0019] Furthermore, in the welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention, in the step of welding the transition layer using single tungsten inert gas welding: a flux-cored welding wire that matches the stainless steel composite layer (e.g., a flux-cored welding wire with performance not lower than that of the stainless steel composite layer) is used, while a mixed gas of argon and CO2 is used for protection.

[0020] Furthermore, in the welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention, in the step of welding the transition layer using single tungsten inert gas welding: the welding voltage is controlled at 13.5-15.5V, the welding current at 150-180A, the welding speed at 120-140mm / min, and the wire feed speed at 2.6-3.0m / min.

[0021] In this embodiment, by using the above-described process, it can be ensured that the width of the hard and brittle transition micro-zone at the interface between the transition layer weld and the base layer weld is less than 8 micrometers, and the hardening degree of the hardened micro-zone is no more than 30% compared to the carbon steel weld. This ensures that the interface area maintains good plastic deformation coordination under heavy load, thereby guaranteeing the reliability of the joint.

[0022] Furthermore, in the welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention, in the step of welding the stainless steel cladding layer using single tungsten inert gas welding: a solid welding wire matching the stainless steel cladding layer (e.g., a solid welding wire with performance not lower than that of the stainless steel cladding layer) is used, while pure argon gas (purity not less than 99%) is used for protection.

[0023] Furthermore, in the welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention, in the step of welding the stainless steel composite layer using single tungsten inert gas welding: the welding voltage is controlled at 13-15V, the welding current at 200-240A, the welding speed at 120-140mm / min, and the wire feed speed at 2.4-2.8m / min.

[0024] In this implementation, the above-described process ensures that the dilution rate of the composite layer weld is less than 3%, thereby guaranteeing that the composite layer weld has good corrosion resistance.

[0025] The welding method for optimizing the interface structure of stainless steel composite plate joints described in this invention has the following advantages and beneficial effects compared to the prior art:

[0026] The welding method described in this invention can effectively control the width and hardening degree of the hard and brittle micro-regions at the welding interface between the transition layer and the substrate layer in the substrate layer-transition layer-stainless steel composite layer welding sequence, effectively improving the bonding performance of the interface. Simultaneously, it can ensure that the dilution rate of the composite layer is controlled at an extremely low level, achieving a reliable connection of the stainless steel composite plate in the substrate layer-transition layer-stainless steel composite layer welding sequence.

[0027] Meanwhile, the welding methods described in this invention are all automated welding technologies and parameterized welding processes, which have little dependence on the welding qualifications and experience of the welders and have good scalability.

[0028] In addition, this method uses a V-groove, which eliminates the need for complex welding grooves, reducing assembly difficulty. Furthermore, the welding method does not need to be changed throughout the entire welding process, as it uses single tungsten inert gas welding. It also has simple equipment requirements, making it very user-friendly for on-site operations in actual engineering projects. Attached Figure Description

[0029] Figure 1 The diagram schematically illustrates the bevel used in the welding method for optimizing the interface structure of stainless steel composite plate joints according to the present invention.

[0030] Figure 2 The cross-sectional morphology of the stainless steel composite plate joint prepared by the welding method of the optimized stainless steel composite plate joint interface structure according to Example 1 of the present invention after being etched by the stainless steel etchant - Karin reagent is shown.

[0031] Figure 3 The image shows the metallographic structure of the stainless steel composite plate joint after etching with a stainless steel etchant-Carlin reagent, following the welding method of the optimized stainless steel composite plate joint interface structure according to Embodiment 1 of the present invention. The transition layer and the interface between the carbon steel weld and the composite plate joint are shown.

[0032] Figure 4 The image shows the plastic deformation at the interface between the transition layer and the carbon steel weld in a stainless steel composite plate joint prepared by the welding method of the optimized stainless steel composite plate joint interface structure according to Embodiment 1 of the present invention, under a large load indentation of 30 kgf. Detailed Implementation

[0033] The welding method for optimizing the interface structure of stainless steel composite plate joints according to the present invention will be further explained and described below with reference to specific embodiments and accompanying drawings. However, this explanation and description do not constitute an undue limitation on the technical solution of the present invention.

[0034] Figure 1 It shows two spliced ​​stainless steel composite panels, A and B. Figure 1 The dashed line O in the figure represents the splicing seam. The stainless steel composite plate includes a stainless steel composite layer 1 and a carbon steel substrate layer 2, with a transition layer at the interface between the stainless steel composite layer 1 and the carbon steel substrate layer 2. Figure 1 The designation "b1" indicates the distance between the surface of the carbon steel substrate layer and its interface with the stainless steel cladding layer, while the designation "b2" indicates the distance between the surface of the stainless steel cladding layer and its interface with the carbon steel substrate layer.

[0035] In one specific embodiment, a stainless steel composite plate with the grade SUS304 / Q235 can be used, that is, the carbon steel base layer material is Q235 and the stainless steel composite layer material is SUS304. The thickness of the stainless steel composite plate is 10mm, wherein b1 of the stainless steel composite plate is 8mm and b2 is 2mm.

[0036] In some embodiments, the welding method for optimizing the interfacial structure of stainless steel composite plate joints may include the following steps:

[0037] 100: Processing is performed at the welding position of the two spliced ​​stainless steel composite plates A and B as follows. Figure 1 The bevel shown. Specifically, a V-shaped bevel is machined on the welding section of the stainless steel composite plate, and a blunt edge 7 is provided at the bottom of the V-shaped bevel.

[0038] The angle between the inclined part 6 of the V-shaped bevel and the vertical direction is... Figure 1 The value is represented by α. In some more specific embodiments, the angle α between the inclined portion 6 of the V-shaped bevel and the vertical direction can be controlled to be ≥ (1.5b1)°.

[0039] The thickness of the blunt edge is Figure 1 The value is represented by b3. In some more specific implementations, b3 can be controlled between 1 and 3 mm.

[0040] Assembly gap at Figure 1 The assembly clearance w2 is indicated by "w2". In some more specific implementations, the assembly clearance w2 can be 1-3 mm.

[0041] This implementation method can effectively reduce the operational difficulty of single tungsten inert gas welding.

[0042] 200: The carbon steel substrate layer is welded using single tungsten inert gas welding to obtain weld 3 of the carbon steel substrate layer. The shielding gas used for welding is pure argon gas with a purity of not less than 99%. Solid carbon steel welding wire that matches the carbon steel substrate layer is used for welding, such as ER50-6 solid welding wire. The welding process parameters can be controlled as follows: welding voltage is 13-16V, welding current is 220-280A, welding speed is 100-150mm / min, and wire feed speed is 2.4-2.8m / min.

[0043] 300: The transition layer is welded using single tungsten inert gas (TIG) welding to obtain transition layer weld 4. During welding, the shielding gas is a mixture of argon and CO2, such as 78% Ar + 18% CO2. The welding material is flux-cored wire that matches the stainless steel cladding layer. The welding process parameters can be controlled as follows: welding voltage is 13.5-15.5V, welding current is 150-180A, welding speed is 120-140mm / min, and wire feed speed is 2.6-3.0m / min.

[0044] By employing the above welding process, it can be ensured that the width of the hard and brittle transition micro-zone at the interface between the transition layer weld and the carbon steel weld is less than 8 micrometers, and the hardening degree of the hardened micro-zone is no more than 30% compared to the carbon steel weld. This ensures that the interface area maintains good plastic deformation coordination under heavy load, thereby guaranteeing the reliability of the joint.

[0045] 400: The stainless steel cladding layer is welded using single tungsten inert gas (TIG) welding to obtain weld 5 of the stainless steel cladding layer. The shielding gas used for welding is pure argon gas with a purity of not less than 99%. Solid welding wire matching the stainless steel cladding layer is used for welding, such as ER309L. The welding process parameters can be controlled as follows: welding voltage is 13-15V, welding current is 200-240A, welding speed is 120-140mm / min, and wire feed speed is 2.4-2.8m / min.

[0046] By employing the above welding process, it can be ensured that the dilution rate of the stainless steel clad layer weld is less than 3%, thereby guaranteeing that the stainless steel clad layer weld has good corrosion resistance.

[0047] To further demonstrate the technical effects of the preferred embodiments of this invention, Table 1 lists the characteristic parameters of the bevel used in the preferred embodiments 1-5 of this invention.

[0048] Table 1.

[0049] Example Bevel angle α (°) <![CDATA[b3(mm)]]> <![CDATA[w2(mm)]]> Example 1 20 2 2 Example 2 15 1 2 Example 3 25 3 2 Example 4 18 2 1 Example 5 12 1 3

[0050] Table 2 lists the welding process parameters used in the step of forming the carbon steel substrate layer weld 3 in the preferred embodiments 1-5 of the present invention.

[0051] Table 2.

[0052]

[0053] Table 3 lists the welding process parameters used in the step of forming the transition layer weld 4 in the preferred embodiments 1-5 of the present invention.

[0054] Table 3.

[0055]

[0056] Table 4 lists the welding process parameters used in the step of forming the stainless steel composite layer weld 5 in the preferred embodiments 1-5 of the present invention.

[0057] Table 4.

[0058]

[0059]

[0060] Furthermore, to demonstrate the effectiveness of the preferred embodiment, Table 5 lists the Cr content of each base material layer and weld in the welded joint of the stainless steel composite plate obtained by welding in Embodiment 1 of the present invention. The dilution rate D1 of the transition layer weld and the dilution rate D2 of the stainless steel composite layer weld can be calculated. As can be seen from Table 5, the dilution rate level D2 of the stainless steel composite layer weld is less than 3%, thereby ensuring that the composite layer weld has good corrosion resistance.

[0061] Table 5.

[0062]

[0063] Figure 2 The cross-sectional morphology of the stainless steel composite plate joint prepared by the welding method of the optimized stainless steel composite plate joint interface structure according to Example 1 of the present invention after being etched by the stainless steel etchant - Karin reagent is shown.

[0064] from Figure 2 As can be seen, the welded joint is well bonded and there are no welding defects.

[0065] Figure 3 The image shows the metallographic structure of the stainless steel composite plate joint after etching with a stainless steel etchant-Carlin reagent, following the welding method of the optimized stainless steel composite plate joint interface structure according to Embodiment 1 of the present invention. The transition layer and the interface between the carbon steel weld and the composite plate joint are shown.

[0066] from Figure 3 As can be seen, the width of the hardened micro-zone was effectively suppressed to below 8 mm, and the degree of hardening was effectively controlled. Its in-layer hardness was 312 HV, which is only 29.0% compared to the hardening degree of carbon steel weld.

[0067] Figure 4 The image shows the plastic deformation at the interface between the transition layer and the carbon steel weld in a stainless steel composite plate joint prepared by the welding method of the optimized stainless steel composite plate joint interface structure according to Embodiment 1 of the present invention, under a large load indentation of 30 kgf.

[0068] from Figure 4As can be seen from the above, the stainless steel composite plate joint prepared by the method described in this invention exhibits good plastic deformation consistency in the three layers of the transition layer weld, the base layer weld, and the hardened micro-zone under heavy load, without significant plastic deformation mismatch or cracking failure, and the interface bonding quality is stable and reliable.

[0069] It should be noted that the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0070] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A welding method for optimizing the interfacial structure of a stainless steel composite plate joint, wherein the stainless steel composite plate comprises a substrate layer and a stainless steel cladding layer, and a transition layer is provided at the interface between the substrate layer and the stainless steel cladding layer; characterized in that, The welding method includes the following steps: A V-shaped bevel is machined on the welding section of the stainless steel composite plate, and a blunt edge is set at the bottom of the V-shaped bevel. The substrate layer is welded using single tungsten inert gas welding with pure argon gas protection: the welding voltage is controlled at 13-16V, the welding current at 220-280A, the welding speed at 100-150mm / min, and the wire feed speed at 2.4-2.8m / min. The transition layer is welded using single tungsten inert gas (TIG) welding with a mixed gas shield of argon and CO2: the welding voltage is controlled at 13.5-15.5V, the welding current at 150-180A, the welding speed at 120-140mm / min, and the wire feed speed at 2.6-3.0m / min. Welding of stainless steel cladding layers is performed using single tungsten inert gas (TIG) welding with pure argon gas protection: control the welding voltage at 13-15V, the welding current at 200-240A, the welding speed at 120-140mm / min, and the wire feed speed at 2.4-2.8m / min.

2. The welding method as described in claim 1, characterized in that, The angle α between the inclined part of the V-shaped bevel and the vertical direction is ≥ (1.5b1)°, where b1 represents the distance from the surface of the substrate layer to the interface between it and the stainless steel composite layer, and its unit parameter is mm.

3. The welding method as described in claim 1, characterized in that, The thickness of the blunt edge b3 is 1-3 mm.

4. The welding method as described in claim 1, characterized in that, The assembly gap w2 of the V-shaped bevel is 1-3mm.

5. The welding method as described in claim 1, characterized in that, In the step of welding the substrate layer using single tungsten inert gas welding: a solid carbon steel welding wire that matches the substrate layer is used.

6. The welding method as described in claim 1, characterized in that, In the step of welding the transition layer using single tungsten inert gas welding: a flux-cored welding wire that matches the stainless steel cladding layer is used.

7. The welding method as described in claim 1, characterized in that, In the process of welding stainless steel cladding layers using single tungsten inert gas welding: a solid welding wire that matches the stainless steel cladding layer is used.

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