Automatic welding method for stainless steel composite plate

Abstract

The invention discloses an automatic welding method for a stainless steel composite plate, the stainless steel composite plate comprises a base material layer and a stainless steel composite material layer, and a transition layer is arranged at the bonding interface of the base material layer and the stainless steel composite material layer. The method comprises the steps that a first trapezoidal groove is machined in the position, corresponding to a base material layer, of the welding section of the stainless steel composite plate; a second trapezoidal groove is machined in the position, corresponding to the transition layer, of the welding section of the stainless steel composite plate, and the first trapezoidal groove and the second trapezoidal groove form a first single-side step; a groove is not machined in the position, corresponding to the stainless steel composite material layer, of the welding section of the stainless steel composite plate, and a second trapezoidal groove forms a second single-side step on the stainless steel composite material layer; zero-clearance self-fusion welding is conducted on the stainless steel composite layer through laser; a stainless steel welding wire matched with the stainless steel composite material layer is used, and laser is adopted for conducting wire filling welding on the transition layer; and a welding wire matched with the base material layer is used, and argon tungsten-arc welding is adopted for conducting wire filling welding on the base material layer.

Description

Technical Field

[0001] The invention relates to a welding method, in particular to a welding method for a composite plate. Background Art

[0002] When connecting stainless steel composite plates, multi-layer and multi-pass welding should be used, that is, the joint weld is divided into a composite stainless steel weld, a transition layer stainless steel weld and a base carbon steel weld, and they are welded separately to ensure the corrosion resistance and overall toughness of the joint composite weld.

[0003] When using this welding method, attention must be paid to controlling the dilution rate of key welds. For example, in the welding sequence of composite layer-transition layer-base layer (this welding sequence can only be used in closed welding conditions of small composite plate components due to limited operating space), the carbon steel weld adjacent to the transition layer can easily undergo martensiticization due to the melting of alloy elements such as Cr and Ni in the stainless steel, thereby deteriorating the plastic toughness of the joint.

[0004] At present, in the closed welding conditions of small stainless steel composite plate components, due to limited operating space, single-sided welding starting from the composite layer has to be used. In this case, if mixed welding materials are used (i.e., carbon steel welds are filled with carbon steel welding materials, and transition layers and composite layers are filled with stainless steel welding materials), the joint welds will be significantly embrittled.

[0005] The existing practice in this regard is to fill the entire weld with stainless steel welding wire. However, such a solution significantly increases the amount of stainless steel welding materials used, increases welding costs while reducing welding efficiency. More importantly, it reduces the structural strength of the entire weld joint, posing a hidden danger to the long-term stable service of the composite plate component.

[0006] In addition, the Chinese patent document with the publication number CN 112122783A and the publication date of December 25, 2020, entitled "A method for laser butt welding of carbon steel-nickel alloy composite plates", discloses: the use of laser welding self-melting or wire-filling welding methods to achieve the connection of composite plates in the welding sequence of composite layer-transition layer-base layer. However, the main problem it solves is the problem that composite plate components cannot be connected under closed welding conditions, and the organizational state of the joints is not paid attention to and controlled.

[0007] The Chinese patent document with publication number CN114888410A and publication date of August 12, 2022, entitled "A welding process for reverse welding of duplex stainless steel composite plates" discloses: arranging the base layer after the transition layer and the composite layer weld to ensure the corrosion resistance of the composite layer and the bending performance of the weld as a whole. However, the welding method in this invention is not a single-sided welding starting from the composite layer, so it cannot be applied in the closed welding condition of composite plate components in actual engineering.

[0008] Different from the above-mentioned existing technical solutions, the inventors have adopted a brand-new design and hope to provide an automated welding method for stainless steel composite plates. This method can avoid the martensiticization of carbon steel weld bead structure under the premise of using mixed welding materials by specially designing grooves, comprehensively utilizing laser welding and arc welding methods, matching optimized process parameters, and realizing reliable connection of stainless steel composite plates in the welding sequence of composite layer-transition layer-base layer. Summary of the invention

[0009] One of the purposes of the present invention is to provide an automated welding method for stainless steel composite plates. The method avoids martensiticization of carbon steel welds under the premise of using mixed welding materials for filling, and realizes reliable connection of stainless steel composite plates in the welding sequence of composite layer-transition layer-base layer, through the design of special grooves and the comprehensive use of laser welding and tungsten inert gas welding.

[0010] In order to achieve the above object, the present invention provides an automated welding method for a stainless steel composite plate, wherein the stainless steel composite plate comprises a substrate layer and a stainless steel composite layer, wherein a transition layer is provided at a bonding interface between the substrate layer and the stainless steel composite layer, and the automated welding method comprises the steps of:

[0011] A first trapezoidal groove is processed at a position corresponding to the base material layer on the welding cross section of the stainless steel composite plate; a second trapezoidal groove is processed at a position corresponding to the transition layer on the welding cross section of the stainless steel composite plate, and the first trapezoidal groove and the second trapezoidal groove form a first single-sided step; no groove is processed at a position corresponding to the stainless steel composite layer on the welding cross section of the stainless steel composite plate, and the second trapezoidal groove forms a second single-sided step on the stainless steel composite layer;

[0012] Laser welding is used to perform autogenous welding on the stainless steel composite layer;

[0013] Use stainless steel welding wire that matches the stainless steel composite layer and use laser welding to fill the transition layer with wire;

[0014] The base material layer is welded by filler wire using tungsten inert gas arc welding using welding wire that matches the base material layer.

[0015] Furthermore, in the automated welding method for stainless steel composite plates described in the present invention, the bottom width w1 / 2 of the second single-sided step is ≥ the laser spot radius of laser welding.

[0016] In this embodiment, the bottom width w1 / 2 of the second single-sided step is ≥ the laser spot radius of laser welding, which can ensure that the weld of the composite material layer is smoothly welded and does not melt the base carbon steel.

[0017] Furthermore, in the automated welding method for stainless steel composite plates described in the present invention, the top width w2 / 2 of the second single-sided step is ≤1.5 mm.

[0018] In this embodiment, by controlling the top width of the second single-sided step, ie, the single-sided width of the top of the transition layer weld groove to ≤1.5 mm, the amount of excess stainless steel weld melted into the base carbon steel weld can be reduced.

[0019] Furthermore, in the automated welding method for stainless steel composite plates described in the present invention, the width w3 of the first single-sided step is ≥(5+0.1b1), where b1 represents the distance from the surface of the substrate layer to the bonding interface between the substrate layer and the stainless steel composite layer.

[0020] Furthermore, in the automated welding method for stainless steel composite plates described in the present invention, the single-side angle α of the first trapezoidal groove is ≥ (1.5b1)°, where b1 represents the distance from the surface of the substrate layer to the bonding interface between the substrate layer and the stainless steel composite layer.

[0021] Furthermore, in the automated welding method for stainless steel composite plates of the present invention, a distance b3 between the first single-sided step and the bonding interface of the stainless steel composite layer is 1-2 mm.

[0022] In the above-mentioned embodiment, the operability of welding the base material layer with a filler wire by using tungsten inert gas arc welding can be further ensured.

[0023] Furthermore, in the automated welding method for stainless steel composite plates described in the present invention, in the step of performing autogenous welding on the stainless steel composite layer by laser welding, the diameter of the laser spot used is ≤1 mm.

[0024] Furthermore, in the automated welding method for stainless steel composite plates described in the present invention, in the step of using laser welding to perform self-fusion welding on the stainless steel composite layer: the laser power is controlled to be 4.0-5.0KW, the welding speed is 3.0-3.5m / min, and the positive defocus is 0-5mm.

[0025] Furthermore, in the automated welding method for stainless steel composite plates described in the present invention, in the step of using laser welding to perform wire-filling welding on the transition layer, the diameter of the laser spot used is ≤1 mm.

[0026] Furthermore, in the automated welding method for stainless steel composite plates described in the present invention, in the step of using laser welding to perform wire welding on the transition layer: the laser power is controlled to be 5.0-6.0KW, the welding speed is 3.0-4.0m / min, the positive defocus is 10-15mm, the wire feeding speed is 2.0-2.5m / min, and the wire feeding angle is 45-60°.

[0027] In this embodiment, the above welding process is combined with a specially designed transition layer weld position groove to control the top width of the transition layer weld to less than 3 mm, so as to reduce the amount of stainless steel weld elements melted into the subsequent carbon steel weld.

[0028] Furthermore, in the automated welding method for stainless steel composite plates described in the present invention, in the step of using tungsten inert gas arc welding to perform filler wire welding on the substrate layer: the welding voltage is controlled to be 13.0-15.0V, the welding current is 180-220A, the welding speed is 160-180mm / min, the wire feeding speed is 2.0-2.6m / min, and the swing width is 1-4mm.

[0029] In this embodiment, the welding process can effectively reduce the penetration depth while ensuring good welding forming, and at the same time, in combination with the obtained transition layer weld with a narrow width, the dilution rate of the carbon steel weld, especially the carbon steel weld in direct contact with the transition layer weld, can be controlled to below 4.0%, thereby avoiding the formation of martensitic structure in the carbon steel weld.

[0030] The automated welding method for stainless steel composite plates of the present invention has the following advantages and beneficial effects compared with the prior art:

[0031] The automated welding method for the stainless steel composite plate of the present invention can effectively avoid the generation of hard and brittle structures, improve the reliability of joint connection and significantly reduce the usage of stainless steel welding materials, thereby reducing welding costs and improving joint strength and welding efficiency.

[0032] In the automated welding method of the stainless steel composite plate described in the present invention, since the methods adopted are both automated welding technology and parameterized welding processes, they are less dependent on the welding qualifications and experience of the welders, and therefore have good scalability.

[0033] In the automated welding method of the stainless steel composite plate described in the present invention, the problem of the carbon steel weld producing a hard and brittle martensitic structure due to excessive dilution in the welding condition of the stainless steel composite plate component where welding is started from the composite layer first can be effectively solved, thereby obtaining a reliable welded joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The schematic diagram of the groove used in the automated welding method of the stainless steel composite plate of the present invention is schematically shown.

[0035] Figure 2 The figure shows the morphology of the welded joint of the composite plate prepared by the automated welding method of Example 1 of the present invention after being corroded by nitric acid.

[0036] Figure 3The metallographic structure photograph of the transition layer / carbon steel weld joint cross section of the welded joint of the composite plate prepared by the automated welding method of Example 1 of the present invention after being corroded by nitric alcohol is shown. DETAILED DESCRIPTION

[0037] The automated welding method for stainless steel composite plates of the present invention will be further explained and illustrated below in conjunction with specific embodiments and drawings of the specification. However, such explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0038] The present invention aims to apply automated welding to stainless steel composite plates. Figure 1 Two stainless steel composite plates A and B are shown in FIG. Figure 1 The dotted line O in the figure represents a joint. The stainless steel composite plate comprises a carbon steel substrate layer 1, a stainless steel composite layer 2, and a transition layer between the carbon steel substrate layer 1 and the stainless steel composite layer 2 (the transition layer is an atomic diffusion layer between the substrate layer and the composite layer, which is difficult to see from the macroscopic structure and is therefore not shown separately in the figure). Figure 1 The middle mark "b3" represents the distance between the first single-sided step and the bonding interface of the stainless steel composite layer, "b1" represents the distance between the surface of the carbon steel substrate layer and the bonding interface between it and the stainless steel composite layer, and "b2" represents the distance between the surface of the stainless steel composite layer and the bonding interface between it and the carbon steel substrate layer.

[0039] In a specific example, a stainless steel composite plate of grade SUS304 / Q235 can be used, and the plate thickness is 10 mm, wherein the stainless steel composite layer is SUS304, the carbon steel substrate layer is Q235, the thickness of b2 is 2 mm, and the thickness of b1 is 8 mm.

[0040] In some embodiments, an automated welding method for stainless steel composite plates comprises the steps of:

[0041] 100: Processing at the welding position of two spliced ​​stainless steel composite plates A and B as follows Figure 1 The groove shown. A first trapezoidal groove 6 is processed at a position corresponding to the base material layer on the welding section of the stainless steel composite plate; a second trapezoidal groove 8 is processed at a position corresponding to the transition layer on the welding section of the stainless steel composite plate, the first trapezoidal groove 6 and the second trapezoidal groove 8 form a first single-sided step 7, and the second trapezoidal groove forms a second single-sided step 9 on the stainless steel composite layer; no groove is processed at a position corresponding to the stainless steel composite layer on the welding section of the stainless steel composite plate, that is, the welding surface 10 of the stainless steel composite layer is a vertical plane.

[0042] 200: The stainless steel composite layer is self-welded by laser welding to form a composite layer weld 3.

[0043] 300: Use stainless steel welding wire that matches the stainless steel composite layer, and use laser welding to fill the transition layer with wire to form a transition layer weld 4. Figure 3 The "w2" here represents the width of the top of the transition layer weld.

[0044] 400: Use carbon steel welding wire that matches the carbon steel substrate layer, and use tungsten inert gas arc welding to perform wire welding on the carbon steel substrate layer to form a substrate layer weld 5.

[0045] Preferably, in some embodiments, the bottom width w1 / 2 of the second single-sided step is ≥ the laser spot radius of laser welding, that is, the total bottom width w1 of the two second single-sided steps formed by the two spliced ​​stainless steel composite plates A and B is ≥ the laser spot diameter of laser welding. This setting can ensure that the weld of the composite layer is smoothly welded and formed without melting the base carbon steel.

[0046] Preferably, in some embodiments, the top width of the second single-sided step w2 / 2≤1.5mm, that is, the total top width w2≤3mm of the two second single-sided steps formed by the two spliced ​​stainless steel composite plates A and B. This design can reduce the amount of excess stainless steel weld melted into the base carbon steel weld.

[0047] In addition, in some embodiments, in order to further improve the operability of tungsten inert gas arc welding for welding the base material layer with a filler wire, the width w3 of the first unilateral step can be controlled to be ≥ (5 + 0.1b1), and the unilateral angle α of the first trapezoidal groove can be ≥ (1.5b1) °, where b1 represents the distance between the surface of the base material layer and the bonding interface between it and the stainless steel composite layer; the distance b3 between the first unilateral step and the bonding interface of the stainless steel composite layer is 1-2 mm.

[0048] In addition, in some preferred embodiments, in step 200, the diameter of the laser spot used is ≤1 mm; the laser power is controlled to be 4.0-5.0 KW, the welding speed is 3.0-3.5 m / min, and the positive defocus is 0-5 mm.

[0049] In step 300: the filler welding wire can use the stainless steel welding wire ER309L with performance not lower than that of the stainless steel composite layer, and the laser spot diameter used is ≤1mm; the laser power is controlled to be 5.0-6.0KW, the welding speed is 3.0-4.0m / min, the positive defocus is 10-15mm, the wire feeding speed is 2.0-2.5m / min, and the wire feeding angle is 45-60°.

[0050] In this embodiment, the above welding process is combined with a specially designed transition layer weld position groove to control the top width of the transition layer weld to less than 3 mm, so as to further reduce the amount of stainless steel weld elements melted into the subsequent carbon steel weld.

[0051] In step 400: carbon steel welding wire ER50-6 matching the base material can be used for welding, and the welding voltage is controlled to be 13.0-15.0V, the welding current is 180-220A, the welding speed is 160-180mm / min, the wire feeding speed is 2.0-2.6m / min, and the swing width is 1-4mm.

[0052] In this embodiment, the welding process can effectively reduce the penetration depth while ensuring good welding forming, and at the same time, in combination with the obtained transition layer weld with a narrow width, the dilution rate of the carbon steel weld, especially the carbon steel weld in direct contact with the transition layer weld, can be controlled to below 4.0%, thereby avoiding the formation of martensitic structure in the carbon steel weld.

[0053] In order to further reflect the preferred implementation of this case, Table 1 lists the characteristic parameters of the grooves used in the preferred embodiments 1-5 of the present invention.

[0054] Table 1.

[0055]

[0056]

[0057] Table 2 lists the welding process parameters used in step 200 of forming a composite material layer weld in preferred embodiments 1-5 of the present invention.

[0058] Table 2.

[0059]

[0060] Table 3 lists the welding process parameters used in step 300 of forming the transition layer weld in preferred embodiments 1-5 of the present invention.

[0061] Table 3.

[0062]

[0063] Table 4 lists the welding process parameters used in step 400 of forming the base material layer weld in preferred embodiments 1-5 of the present invention.

[0064] Table 4.

[0065]

[0066]

[0067] In addition, in order to prove the implementation effect of the preferred embodiment, Table 5 lists the Cr element content of each layer of the base material and the weld in the joint of the stainless steel composite plate obtained by welding in Example 1 of the present invention. It can be calculated that the dilution rate of the carbon steel weld in contact with the transition layer relative to the stainless steel composite weld is only 2.64%, which is lower than 4.0%, thereby avoiding the formation of martensitic structure in the carbon steel weld.

[0068] Table 5.

[0069]

[0070] Figure 2 The figure shows the morphology of the welded joint of the composite plate prepared by the automated welding method of Example 1 of the present invention after being corroded by nitric acid.

[0071] from Figure 2 It can be seen that the weld joint is well bonded, and it can be seen that due to the application of the method of the present invention, the width of the transition layer weld is effectively controlled, which helps to reduce the dilution rate of the carbon steel weld.

[0072] Figure 3 The metallographic structure photograph of the transition layer / carbon steel weld joint cross section of the welded joint of the composite plate prepared by the automated welding method of Example 1 of the present invention after being corroded by nitric alcohol is shown.

[0073] from Figure 3 It can be seen that the transition layer weld is not corroded, indicating that it still maintains the austenite structure of the base material, while the structure type of the carbon steel weld adjacent to the transition layer is ferrite + pearlite, and no martensite structure appears, which means that this layer of weld has not undergone obvious hardening.

[0074] It should be noted that the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0075] It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with the contents disclosed by those skilled in the art from the present invention, and all should belong to the protection scope of the present invention.

Claims

1. An automated welding method for a stainless steel composite plate, the stainless steel composite plate comprising a substrate layer and a stainless steel composite layer, wherein a transition layer is provided at a bonding interface between the substrate layer and the stainless steel composite layer; It is characterized in that The automated welding method comprises the steps of: A first trapezoidal groove is processed at a position corresponding to the base material layer on the welding cross section of the stainless steel composite plate; a second trapezoidal groove is processed at a position corresponding to the transition layer on the welding cross section of the stainless steel composite plate, and the first trapezoidal groove and the second trapezoidal groove form a first single-sided step; no groove is processed at a position corresponding to the stainless steel composite layer on the welding cross section of the stainless steel composite plate, and the second trapezoidal groove forms a second single-sided step on the stainless steel composite layer; Laser welding is used to perform autogenous welding on the stainless steel composite layer; Use stainless steel welding wire that matches the stainless steel composite layer and use laser welding to fill the transition layer with wire; The base material layer is welded by filler wire using tungsten inert gas arc welding using welding wire that matches the base material layer.

2. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: The bottom width w1 / 2 of the second single-sided step is ≥ the laser spot radius of laser welding.

3. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: A top width w2 / 2 of the second single-sided step is ≤1.5 mm.

4. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: The width w3 of the first single-sided step is ≥(5+0.1b1), where b1 represents the distance from the surface of the substrate layer to the bonding interface between the substrate layer and the stainless steel composite layer.

5. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: The single-side angle α of the first trapezoidal groove is ≥(1.5b1)°, where b1 represents the distance from the surface of the substrate layer to the bonding interface between the substrate layer and the stainless steel composite layer.

6. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: The distance b3 between the first single-sided step and the bonding interface of the stainless steel composite layer is maintained at 1-2 mm.

7. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: In the step of self-fusion welding the stainless steel composite layer by laser welding, the diameter of the laser spot used is ≤1 mm.

8. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: In the step of self-fusion welding the stainless steel composite layer by laser welding: the laser power is controlled to be 4.0-5.0KW, the welding speed is 3.0-3.5m / min, and the positive defocus is 0-5mm.

9. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: In the step of performing wire welding on the transition layer by laser welding, the diameter of the laser spot used is ≤1 mm.

10. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: In the step of using laser welding to filler wire welding the transition layer: control the laser power to 5.0-6.0KW, the welding speed to 3.0-4.0m / min, the positive defocus to 10-15mm, the wire feeding speed to 2.0-2.5m / min, and the wire feeding angle to 45-60°.

11. The automated welding method for stainless steel composite plates according to claim 1, characterized in that: In the step of welding the base material layer with filler wire by tungsten inert gas arc welding: the welding voltage is controlled to be 13.0-15.0V, the welding current is 180-220A, the welding speed is 160-180mm / min, the wire feeding speed is 2.0-2.6m / min, and the swing width is 1-4mm.

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