Welding method for optimizing interface structure of stainless steel composite plate joint

Abstract

The invention discloses a welding method for optimizing the joint interface structure of 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 welding method comprises the steps that a V-shaped groove is machined in the welding section of the stainless steel composite plate, and a truncated edge is arranged at the bottom of the V-shaped groove; welding the base material layer by adopting single tungsten electrode argon arc welding; welding the transition layer by adopting single tungsten electrode argon arc welding; and welding the stainless steel composite material layer by adopting single tungsten electrode argon arc welding. According to the method, the width and the hardening degree of the hard and brittle micro-area on the welding interface of the transition layer and the base material layer in the welding sequence of the base material layer, the transition layer and the composite material layer can be effectively controlled, and the bonding performance of the interface is effectively improved. And meanwhile, the dilution rate of the composite material layer can be controlled at an extremely low level, and reliable connection of the stainless steel composite plate is ensured.

Description

Technical Field

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

[0002] Stainless steel composite plate generally refers to a binary metal structural material that is made by combining carbon steel and stainless steel through rolling, explosive composite and other methods. It not only has good mechanical properties but also meets functional requirements such as corrosion resistance and aesthetics.

[0003] Since the two component metals, stainless steel and carbon steel, have quite different compositions and physical properties, multi-layer and multi-pass welding should be used when welding stainless steel composite plates in engineering, that is, the joint welds are divided into composite stainless steel welds, transition layer stainless steel welds and base carbon steel welds, and they are welded separately.

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

[0005] However, for the welding of stainless steel clad plates in the welding sequence of base layer-transition layer-composite layer, the key points of joint quality control include not only the dilution rate control of the composite stainless steel weld, but also the interface control problem between the transition layer and the base layer.

[0006] Since the transition layer, the composite layer and the carbon steel substrate layer need to use stainless steel and carbon steel welding materials that match the parent material during welding, the welding process of the transition layer and the carbon steel weld is essentially a dissimilar metal connection between stainless steel and carbon steel. A transition hardened micro-zone with martensite as the main structure will inevitably appear on the connection interface. The excessive width and high hardening degree of the micro-zone will cause serious non-uniform plastic deformation in the interface area when subjected to load, thereby increasing the risk of cracking failure. Therefore, if this area is not controlled, it will be a hidden danger to the service safety of the joint. Summary of the invention

[0007] The purpose of the present invention is to provide a welding method for optimizing the interface structure of the stainless steel composite plate joint. The method is based on a V-shaped groove and adopts a single tungsten electrode argon arc welding method. The width and hardening degree of the hard and brittle micro-regions on the welding interface of the transition layer and the substrate layer in the welding sequence of the substrate layer-transition layer-stainless steel composite layer can be effectively controlled, and the dilution rate of the stainless steel composite layer can be controlled at an extremely low level. While ensuring the corrosion resistance requirements of the stainless steel composite layer, the bonding performance of the interface is effectively improved, and the reliable connection of the stainless steel composite plate in the welding sequence of the substrate layer-transition layer-stainless steel composite layer is realized.

[0008] In order to achieve the above object, the present invention provides a welding method for optimizing the interface structure of a stainless steel composite plate joint, wherein the stainless steel composite plate comprises a substrate layer and a stainless steel composite layer, and a transition layer is provided at the interface between the substrate layer and the stainless steel composite layer; the welding method comprises the steps of:

[0009] Processing a V-shaped groove on the welding section of the stainless steel composite plate, and setting a blunt edge at the bottom of the V-shaped groove;

[0010] The substrate layer is welded by single tungsten-in-polarity argon arc welding;

[0011] The transition layer is welded by single tungsten-arc argon welding;

[0012] The stainless steel composite layer is welded by single tungsten inert gas arc welding.

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

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

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

[0016] In this embodiment, the operational difficulty of single tungsten electrode argon arc welding can be effectively reduced through the above process design.

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

[0018] Furthermore, in the welding method for optimizing the interface structure of the stainless steel composite plate joint described in the present invention, in the step of welding the substrate layer using single tungsten electrode argon arc welding: the welding voltage is controlled to be 13-16V, the welding current is 220-280A, the welding speed is 100-150mm / min, and the wire feeding speed is 2.4-2.8m / min.

[0019] Furthermore, in the welding method for optimizing the interface structure of the stainless steel composite plate joint described in the present invention, in the step of welding the transition layer using single tungsten electrode argon arc welding: a flux-cored welding wire matching the stainless steel composite layer (for example, a flux-cored welding wire with performance not lower than that of the stainless steel composite layer) is used, and a mixed gas of argon + CO2 is used for protection.

[0020] Furthermore, in the welding method for optimizing the interface structure of the stainless steel composite plate joint described in the present invention, in the step of welding the transition layer using single tungsten electrode argon arc welding: controlling the welding voltage to 13.5-15.5V, the welding current to 150-180A, the welding speed to 120-140mm / min, and the wire feeding speed to 2.6-3.0m / min.

[0021] In this embodiment, the above-mentioned process is used to ensure that the width of the hard-brittle transition micro-zone at the bonding interface of the transition layer weld and the base layer weld is less than 8 microns, and the degree of hardening of the hardened micro-zone is no more than 30% compared to the carbon steel weld, thereby ensuring that the interface area maintains good plastic deformation coordination when subjected to heavy loads, thereby ensuring the reliability of the joint.

[0022] Furthermore, in the welding method for optimizing the interface structure of the stainless steel composite plate joint described in the present invention, in the step of welding the stainless steel composite layer by single tungsten electrode argon arc welding: a solid welding wire matching the stainless steel composite layer (for example, a solid welding wire with performance not lower than that of the stainless steel composite layer) is used, and pure argon gas (purity not less than 99%) is used for protection.

[0023] Furthermore, in the welding method for optimizing the interface structure of the stainless steel composite plate joint described in the present invention, in the step of welding the stainless steel composite layer by single tungsten electrode argon arc welding: the welding voltage is controlled to be 13-15V, the welding current is 200-240A, the welding speed is 120-140mm / min, and the wire feeding speed is 2.4-2.8m / min.

[0024] In this embodiment, the above process is used to ensure that the dilution rate level of the composite material layer weld is less than 3%, thereby ensuring that the composite material layer weld has good corrosion resistance.

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

[0026] The welding method of the present invention can effectively control the width and hardening degree of the hard and brittle micro-regions on the welding interface of the transition layer and the substrate layer in the welding sequence of the substrate layer-transition layer-stainless steel composite layer, and effectively improve the bonding performance of the interface. At the same time, it can ensure that the dilution rate of the composite layer is controlled at an extremely low level, and realize the reliable connection of the stainless steel composite plate in the welding sequence of the substrate layer-transition layer-stainless steel composite layer;

[0027] At the same time, the welding methods described in the present invention are all automated welding technologies and parameterized welding processes, which are less dependent on the welding qualifications and experience of welders and have good scalability;

[0028] In addition, this method uses a V-shaped groove, which does not require the processing of complex welding grooves, reducing the difficulty of assembly. There is no need to change the welding method during the entire welding process. Single tungsten electrode argon arc welding is used, and the equipment requirements are simple, which is very friendly to on-site operations in actual projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The schematic diagram of the groove used in the welding method for optimizing the interface structure of the stainless steel composite plate joint described in the present invention is schematically shown.

[0030] Figure 2 The cross-sectional morphology of a stainless steel composite plate joint prepared by the welding method for optimizing the interface structure of a stainless steel composite plate joint according to Example 1 of the present invention after being corroded by a stainless steel corrosive agent-Carlin's reagent is shown.

[0031] Figure 3 A metallographic structure photograph of the transition layer and the carbon steel weld interface of a stainless steel composite plate joint after being corroded by a stainless steel corrosive agent-Carlin's reagent using the welding method for optimizing the interface structure of a stainless steel composite plate joint according to Example 1 of the present invention is shown.

[0032] Figure 4 The plastic deformation of the transition layer / carbon steel weld interface of the stainless steel composite plate joint prepared by the welding method for optimizing the interface structure of the stainless steel composite plate joint of Example 1 of the present invention is shown under the action of a large load indentation of 30Kgf. DETAILED DESCRIPTION

[0033] The welding method for optimizing the interface structure of the stainless steel composite plate joint according to 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.

[0034] Figure 1 Shows two joined stainless steel composite panels A and B. Figure 1 The dotted line O in the figure represents a joint seam. The stainless steel composite plate comprises a stainless steel composite material layer 1 and a carbon steel substrate layer 2, and a transition layer is provided at the bonding interface between the stainless steel composite material layer 1 and the carbon steel substrate layer 2. Figure 1 The symbol "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 the symbol "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.

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

[0036] In some embodiments, a welding method for optimizing the interface structure of a stainless steel composite plate joint may include the steps of:

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

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

[0039] The thickness of the blunt edge is Figure 1 In some more specific embodiments, b3 can be controlled between 1-3 mm.

[0040] Assembly clearance Figure 1 In some more specific embodiments, the assembly gap w2 may be 1-3 mm.

[0041] By adopting this implementation mode, the operating difficulty of single tungsten electrode argon arc welding can be effectively reduced.

[0042] 200: The carbon steel substrate layer is welded by single tungsten electrode argon arc welding to obtain a carbon steel substrate layer weld 3. The welding shielding gas adopts pure argon gas with a purity of not less than 99%. The welding uses a carbon steel solid welding wire that matches the carbon steel substrate layer, 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 feeding speed is 2.4-2.8m / min.

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

[0044] By adopting the above-mentioned welding process, it can be ensured that the width of the hard-brittle transition micro-zone at the bonding interface of the transition layer weld and the carbon steel weld is less than 8 microns, and the degree of hardening of the hardened micro-zone is no more than 30% compared with the carbon steel weld, thereby ensuring that the interface area maintains good plastic deformation coordination when subjected to heavy loads, thereby ensuring the reliability of the joint.

[0045] 400: The stainless steel composite layer is welded by single tungsten electrode argon arc welding to obtain a stainless steel composite layer weld 5. The welding shielding gas adopts pure argon gas with a purity of not less than 99%. The welding uses a solid welding wire matching the stainless steel composite layer, 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 feeding speed is 2.4-2.8m / min.

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

[0047] In order to further reflect the technical effects of 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.

[0048] Table 1.

[0049] Example Groove 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 steps of forming the carbon steel substrate layer weld 3 in 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 steps of forming the stainless steel composite layer weld 5 in preferred embodiments 1-5 of the present invention.

[0057] Table 4.

[0058]

[0059]

[0060] 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 welded joint of the stainless steel composite plate obtained by welding in Example 1 of the present invention, and the dilution rate D1 of the transition layer weld and the dilution rate D2 of the stainless steel composite layer weld can be calculated. It can be seen from Table 5 that the dilution rate level of the stainless steel composite layer weld D2 is lower 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 a stainless steel composite plate joint prepared by the welding method for optimizing the interface structure of a stainless steel composite plate joint according to Example 1 of the present invention after being corroded by a stainless steel corrosive agent-Carlin's reagent is shown.

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

[0065] Figure 3 A metallographic structure photograph of the transition layer and the carbon steel weld interface of a stainless steel composite plate joint after being corroded by a stainless steel corrosive agent-Carlin's reagent using the welding method for optimizing the interface structure of a stainless steel composite plate joint according to Example 1 of the present invention is shown.

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

[0067] Figure 4 The plastic deformation of the transition layer / carbon steel weld interface of the stainless steel composite plate joint prepared by the welding method for optimizing the interface structure of the stainless steel composite plate joint of Example 1 of the present invention is shown under the action of a large load indentation of 30Kgf.

[0068] from Figure 4It can be seen that the stainless steel composite plate joint prepared by the method described in the present invention, the transition layer weld, the base layer weld, and the hardened micro-area three-layer area show good plastic deformation consistency when subjected to heavy load, without significant plastic deformation mismatch and cracking failure, and the interface bonding quality is stable and reliable.

[0069] 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.

[0070] 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. A welding method for optimizing the interface structure of a stainless steel composite plate joint, wherein the stainless steel composite plate comprises a substrate layer and a stainless steel composite layer, and a transition layer is provided at the interface between the substrate layer and the stainless steel composite layer; characterized in that: The welding method comprises the steps of: Processing a V-shaped groove on the welding section of the stainless steel composite plate, and setting a blunt edge at the bottom of the V-shaped groove; The substrate layer is welded by single tungsten-in-polarity argon arc welding; The transition layer is welded by single tungsten-arc argon welding; The stainless steel composite layer is welded by single tungsten inert gas arc welding.

2. The welding method according to claim 1, characterized in that The angle α between the inclined portion of the V-shaped groove and the vertical direction 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, and its unit parameter is mm.

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

4. The welding method according to claim 1, characterized in that: The assembly clearance w2 of the V-shaped groove is 1-3 mm.

5. The welding method according to claim 1, characterized in that: In the step of welding the substrate layer by using single tungsten inert gas arc welding: a carbon steel solid welding wire matching the substrate layer is used, and pure argon gas protection is used at the same time.

6. The welding method according to claim 1, characterized in that: In the step of welding the substrate layer by single tungsten electrode argon arc welding: the welding voltage is controlled to be 13-16V, the welding current is 220-280A, the welding speed is 100-150mm / min, and the wire feeding speed is 2.4-2.8m / min.

7. The welding method according to claim 1, characterized in that: In the step of welding the transition layer by single tungsten electrode argon arc welding: a flux-cored welding wire matching the stainless steel composite layer is used, and a mixed gas of argon + CO2 is used for protection.

8. The welding method according to claim 1, characterized in that: In the step of welding the transition layer by single tungsten electrode argon arc welding: control the welding voltage to 13.5-15.5V, the welding current to 150-180A, the welding speed to 120-140mm / min, and the wire feeding speed to 2.6-3.0m / min.

9. The welding method according to claim 1, characterized in that: In the step of welding the stainless steel composite material layer by single tungsten electrode argon arc welding: a solid welding wire matching the stainless steel composite material layer is used, and pure argon gas protection is adopted at the same time.

10. The welding method according to claim 1, characterized in that: In the step of welding the stainless steel composite layer by single tungsten electrode argon arc welding: the welding voltage is controlled to be 13-15V, the welding current is 200-240A, the welding speed is 120-140mm / min, and the wire feeding speed is 2.4-2.8m / min.

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