A high-quality welding method for stainless steel composite plates

Abstract

This invention discloses a high-quality welding method for stainless steel composite plates, 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. The high-quality welding method includes the following steps: machining an X-shaped bevel on the welding section of the stainless steel composite plate corresponding to the position of the substrate layer, with a blunt edge in the middle of the X-shaped bevel; opening a trapezoidal bevel on the welding section of the stainless steel composite plate corresponding to the positions of the transition layer and the stainless steel cladding layer; welding the substrate layer using submerged arc welding; welding the transition layer using double tungsten inert gas welding; and welding the stainless steel cladding layer using double tungsten inert gas welding. This method effectively controls the width and hardening degree of the hard and brittle micro-region at the welding interface between the transition layer and the substrate layer in the substrate layer-transition layer-cladding layer welding sequence while ensuring an extremely low dilution rate of the cladding layer, effectively improving the bonding performance of the interface.

Description

Technical Field

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

[0002] Stainless steel composite panels are a new type of multi-component composite metal structural material. While using carbon steel as the base layer to ensure overall strength and toughness, stainless steel is used as the composite layer to achieve functional requirements such as corrosion resistance and aesthetics.

[0003] Due to the significant differences in composition between stainless steel and carbon steel, stainless steel composite plates should be welded using multi-layer, multi-pass welding (i.e., the joint weld should be welded separately for the stainless steel cladding layer, transition layer, and carbon steel base layer) to simultaneously ensure the corrosion resistance of the cladding layer weld and the overall mechanical properties. In most industrial manufacturing scenarios, stainless steel composite plates are welded using the base layer-transition layer-cladding layer sequence. This welding sequence is relatively easy to implement, and more importantly, the compositional transition from carbon steel to stainless steel (i.e., the dilution rate of the cladding layer and transition layer welds) is relatively easy to complete, thus ensuring the corrosion resistance of the cladding layer.

[0004] However, in fact, in the welding sequence of substrate layer-transition layer-composite layer, the key points of welding stainless steel composite plates, in addition to the compositional transition (dilution rate control) from carbon steel in the substrate layer to stainless steel in the composite layer, also include the interface control between the transition layer and the substrate layer.

[0005] Since the aforementioned welding is essentially a dissimilar metal connection between stainless steel and carbon steel, transition micro-regions inevitably form at the interface between the transition layer weld and the base layer weld. Because the main microstructure of these transition micro-regions is martensitic, it leads to significant hardening and brittleness in the interface region. Such hardened and brittle micro-regions cause non-uniform plastic deformation in the interface region under load, resulting in cracking failure. Therefore, the existence of hardened and brittle transition micro-regions at the weld interface between the transition layer and the base layer poses a service safety hazard to the joint and needs to be controlled. However, there is currently no method in the prior art to solve this problem. Summary of the Invention

[0006] The purpose of this invention is to provide a high-quality welding method for stainless steel composite plates. This method is based on a specially designed bevel and uses a variety of arc welding methods. While ensuring an extremely low dilution rate of the stainless steel composite layer, it 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 layer-transition layer-stainless steel composite layer welding sequence. This effectively improves the bonding performance of the interface, thereby enabling high-quality connection of stainless steel composite plates in the substrate layer-transition layer-stainless steel composite layer welding sequence.

[0007] To achieve the above objectives, the present invention provides a high-quality welding method for stainless steel composite plates, 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; the high-quality welding method includes the following steps:

[0008] An X-shaped bevel is machined on the welding section of the stainless steel composite plate at the position corresponding to the base material layer, and a blunt edge is provided in the middle of the X-shaped bevel; a trapezoidal bevel is opened on the welding section of the stainless steel composite plate at the position corresponding to the transition layer and the stainless steel composite layer.

[0009] Submerged arc welding is used to weld the substrate layer;

[0010] The transition layer was welded using dual tungsten inert gas welding;

[0011] The stainless steel composite layer was welded using double tungsten inert gas welding.

[0012] Furthermore, in the high-quality welding method for stainless steel composite plates described in this invention, the angle between the inclined portion and the vertical direction of the X-shaped bevel is consistent with the angle between the inclined portion and the vertical direction of the trapezoidal bevel.

[0013] Furthermore, in the high-quality welding method for stainless steel composite plates described in this invention, the angle between the inclined portion of the X-shaped bevel and the vertical direction, and the angle between the inclined portion of the trapezoidal bevel and the vertical direction, are both α≥(1.5b1)°, where b1 represents the distance between the surface of the substrate layer and its interface with the stainless steel composite layer, and its unit parameter is mm.

[0014] In this implementation, the above-mentioned bevel design facilitates the operation of the welding torch for subsequent submerged arc welding and dual tungsten inert gas welding.

[0015] Furthermore, in the high-quality welding method for stainless steel composite plates described in this invention, the thickness b3 of the blunt edge of the X-shaped groove is controlled within the range of 2-4 mm, and zero-gap assembly is maintained. Combined with the process parameter window of the base submerged arc welding, good forming can be achieved while avoiding the melting and penetration of the first base weld.

[0016] Furthermore, in the high-quality welding method for stainless steel composite plates described in this invention, the single-side width w2 of the trapezoidal bevel step is greater than or equal to (2 + 0.1b1), where b1 represents the distance between the surface of the substrate layer and its interface with the stainless steel composite layer, and its unit parameter is mm.

[0017] Furthermore, in the high-quality welding method for stainless steel composite plates described in this invention, the distance w1 between the step plane of the trapezoidal bevel and the interface between the substrate layer and the stainless steel composite layer is controlled within the range of 0.5b2-0.8b2, where b2 represents the distance from the surface of the stainless steel composite layer to its interface with the substrate layer, and its unit parameter is mm.

[0018] In this implementation, due to the unique arc characteristics of dual tungsten inert gas (TIG) welding, the surface flatness of the workpiece to be welded is required to be high. Therefore, a step can be made in the bevel of the carbon steel substrate layer. Considering the large volume of the TIG welding torch, the distance w1 between the step plane of the trapezoidal bevel and the interface between the carbon steel substrate layer and the stainless steel cladding layer, and the single-side width w2 of the step of the trapezoidal bevel, can be controlled to facilitate subsequent torch operation.

[0019] Furthermore, in the high-quality welding method for stainless steel composite plates described in this invention, in the step of welding the substrate layer using submerged arc welding: a carbon steel welding wire matching the substrate layer is used, the welding current is controlled at 400-600A, the welding voltage at 25-35V, and the welding speed at 0.5-1.0m / min.

[0020] In this embodiment, the above-described method can ensure that the weld of the carbon steel substrate layer has sufficiently good formation, especially that the excess height of the weld of the carbon steel substrate layer can be kept flush with the step, and the high surface flatness will be beneficial to the formation control of the double tungsten inert gas welding.

[0021] Furthermore, in the high-quality welding method for stainless steel composite plates described in this invention, in the step of welding the transition layer using double tungsten inert gas welding: stainless steel welding wire with performance not lower than that of the stainless steel composite layer is used.

[0022] Furthermore, in the high-quality welding method for stainless steel composite plates described in this invention, in the step of welding the transition layer using double tungsten inert gas welding: the welding voltage is controlled at 14-15V, the welding current at 360-420A, the welding speed at 300-340mm / min, the wire feed speed at 4.6-5.0m / min, and the gap between the two tungsten electrodes is 0.5-1.5mm.

[0023] Furthermore, in the high-quality welding method for stainless steel composite plates described in this invention, in the step of welding the stainless steel cladding layer using double tungsten inert gas welding: stainless steel welding wire matching the stainless steel cladding layer is used, the welding voltage is controlled at 14-15V, the welding current at 360-420A, the welding speed at 300-340mm / min, the wire feed speed at 4.6-5.0m / min, and the gap between the two tungsten electrodes is 0.5-1.5mm.

[0024] In this implementation, when the above-described implementation method is used, the dilution rate of the transition layer weld and the stainless steel composite layer can be controlled to below 15% and 3% respectively, with the special design of the stepped composite groove. At the same time, the width of the martensitic hardened layer at the interface between the transition layer and the carbon steel substrate layer is significantly reduced, and its hardening degree compared with the carbon steel substrate layer weld is controlled to below 30%. This ensures that the interface area will not undergo uneven plastic deformation under large loads, thereby improving the reliability of the interface.

[0025] The high-quality welding method for stainless steel composite plates 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 carbon steel substrate layer of the stainless steel composite plate while ensuring an extremely low dilution rate of the stainless steel cladding layer. This effectively improves the bonding performance of the interface, thereby achieving a high-quality connection of the stainless steel composite plate in the welding sequence of carbon steel substrate layer-transition layer-stainless steel cladding layer.

[0027] Meanwhile, the welding method described in this invention employs automated welding technology and parameterized welding processes, which places less emphasis on the welding qualifications and experience of the welders, thus making it highly scalable.

[0028] Furthermore, the welding methods used in this invention are all high-efficiency welding methods, characterized by fast welding speed and high deposition efficiency, which can significantly reduce on-site construction time. Attached Figure Description

[0029] Figure 1 The diagram schematically illustrates the bevel used in the high-quality welding method for stainless steel composite plates described in this invention.

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

[0031] Figure 3 The image shows a metallographic photograph of the interface between the transition layer and the carbon steel weld in the composite plate joint prepared by the high-quality welding method of the stainless steel composite plate according to Example 1 of the present invention, after being etched by the stainless steel etchant - Karin reagent.

[0032] Figure 4The invention demonstrates the plastic deformation at the interface between the transition layer and the carbon steel weld of a composite plate joint prepared by the high-quality welding method of the stainless steel composite plate according to Example 1 of the present invention, under the action of a large load indentation of 30 kgf. Detailed Implementation

[0033] The high-quality welding method for stainless steel composite plates described in this 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 this 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 19mm, wherein b1 of the stainless steel composite plate is 16mm and b2 is 3mm.

[0036] In some embodiments, the high-quality welding method for stainless steel composite plates of the present invention 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 is shown. Specifically, an X-shaped bevel is machined on the welding section of the stainless steel composite plate at the position corresponding to the carbon steel substrate layer. A blunt edge 6 is provided in the middle of the X-shaped bevel, and the thickness of the blunt edge is... Figure 1 It is represented by "b3".

[0038] A trapezoidal bevel is made on the welding section of the stainless steel composite plate at the positions corresponding to the transition layer and the stainless steel cladding layer. The single-side width of the step of the trapezoidal bevel is... Figure 1 In some more specific embodiments, the step width w2 of the trapezoidal bevel can be controlled to be ≥ (2 + 0.1b1); the distance between the step plane of the trapezoidal bevel and the interface between the carbon steel substrate layer and the stainless steel composite layer is... Figure 1In some more specific embodiments, the distance w1 between the step plane of the trapezoidal bevel and the interface between the substrate layer and the stainless steel composite layer can be controlled within the range of 0.5b2-0.8b2. b3 is controlled within the range of 2-4mm, and the two welding test plates are assembled with zero gap.

[0039] In this implementation, due to the unique arc characteristics of dual tungsten inert gas (TIG) welding, the surface flatness of the workpiece to be welded is required to be high. Therefore, a step can be made within the bevel of the carbon steel substrate layer. Considering the large volume of the TIG welding torch, the distance w1 between the step plane of the trapezoidal bevel and the interface between the carbon steel substrate layer and the stainless steel cladding layer, and the single-side width w2 of the step of the trapezoidal bevel, can facilitate subsequent torch operation. At the same time, the blunt edge design and zero-gap assembly ensure that the first base weld will not melt through and will have good formation.

[0040] In some embodiments, the angle between the inclined portion 7 of the X-shaped bevel and the vertical direction is the same as the angle between the inclined portion 8 of the trapezoidal bevel and the vertical direction.

[0041] In some more specific embodiments, the angle between the inclined portion 7 of the X-shaped bevel and the vertical direction, as well as the angle between the inclined portion 8 of the trapezoidal bevel and the vertical direction, can be controlled to be α≥(1.5b1)°.

[0042] This implementation method facilitates the operation of welding torches for subsequent submerged arc welding and dual tungsten inert gas welding.

[0043] 200: Submerged arc welding is used to weld the carbon steel substrate layer to obtain carbon steel substrate layer weld 3. During welding, one weld is made on the inside and one on the outside (the inside weld is made first and then the outside weld is made). The welding is done with carbon steel welding wire that matches the carbon steel substrate layer, such as CHW-S1 welding wire. The welding process parameters can be controlled as follows: welding current is 400-600A, welding voltage is 25-35V, and welding speed is 0.5-1.0m / min.

[0044] By adopting the above welding process, it can be ensured that the weld of the carbon steel substrate layer has a sufficiently good shape. In particular, the weld reinforcement of the carbon steel substrate layer can be kept flush with the step, and the high surface flatness will be beneficial to the shape control of the subsequent double tungsten inert gas welding.

[0045] 300: The transition layer is welded using double tungsten inert gas (TIG) welding to obtain transition layer weld 4. Stainless steel welding wire with performance no less than that of the stainless steel cladding layer is used, such as ER309L stainless steel welding wire. The welding process parameters can be controlled as follows: welding voltage 14-15V, welding current 360-420A, welding speed 300-340mm / min, wire feed speed 4.6-5.0m / min, and the gap between the two tungsten electrodes 0.5-1.5mm. In some specific embodiments, the angle ε between the tungsten electrode arrangement direction and the welding direction can be controlled to 0 degrees.

[0046] 400: The stainless steel cladding layer is welded using dual tungsten inert gas (TIG) welding to obtain weld 5 in the stainless steel cladding layer. A stainless steel welding wire compatible with the stainless steel cladding layer is used, such as ER309L stainless steel welding wire. The welding process parameters can be controlled as follows: welding voltage 14-15V, welding current 360-420A, welding speed 300-340mm / min, wire feed speed 4.6-5.0m / min, and the gap between the two tungsten electrodes 0.5-1.5mm. In some specific embodiments, the angle ε between the tungsten electrode arrangement direction and the welding direction can be controlled to 0 degrees.

[0047] By employing the above welding process, combined with a specially designed stepped composite groove, the dilution rate of the transition layer weld and the stainless steel cladding layer weld can be controlled to below 15% and 3% respectively. At the same time, the width of the martensitic hardened layer at the interface between the transition layer and the carbon steel substrate layer is significantly reduced, and its hardening degree compared to the carbon steel substrate layer weld is controlled to below 30%. This ensures that the interface area will not undergo uneven plastic deformation under heavy loads, thereby improving the reliability of the interface.

[0048] 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.

[0049] Table 1.

[0050]

[0051]

[0052] 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.

[0053] Table 2.

[0054]

[0055] 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.

[0056] Table 3.

[0057]

[0058] Table 4 lists the welding process parameters used in the step of forming the composite layer weld 5 in the preferred embodiments 1-5 of the present invention.

[0059] Table 4.

[0060]

[0061] 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 according to 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 D1 of the transition layer weld is less than 15.00%, and the dilution rate D2 of the stainless steel composite layer weld is less than 3%, thereby ensuring that the composite layer weld has good corrosion resistance.

[0062] Table 5.

[0063]

[0064] Figure 2 The cross-sectional morphology of a composite plate joint prepared by the high-quality welding method of the stainless steel composite plate according to Example 1 of the present invention is shown after being etched by the stainless steel etchant - Karin reagent.

[0065] from Figure 2 As can be seen, the joints prepared by the high-quality welding method of the stainless steel composite plate described in this invention have good bonding and aesthetically pleasing weld formation.

[0066] Figure 3 The image shows a metallographic photograph of the interface between the transition layer and the carbon steel weld in the composite plate joint prepared by the high-quality welding method of the stainless steel composite plate according to Example 1 of the present invention, after being etched by the stainless steel etchant - Karin reagent.

[0067] 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 315 HV, which is only 28.6% of the hardening degree of carbon steel weld.

[0068] Figure 4 The invention demonstrates the plastic deformation at the interface between the transition layer and the carbon steel weld of a composite plate joint prepared by the high-quality welding method of the stainless steel composite plate according to Example 1 of the present invention, under the action of a large load indentation of 30 kgf.

[0069] from Figure 4 As can be seen, the interface structure of the joint prepared by the method of the present invention exhibits good plastic deformation coordination in the three-layer region of transition layer weld, substrate layer weld and hardened micro-region under heavy load, without significant plastic deformation mismatch, and without cracking failure, and the interface bonding quality is stable and reliable.

[0070] 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.

[0071] 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 high-quality welding method for stainless steel composite plates, the stainless steel composite plates comprising 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; Its features are, The high-quality welding method includes the following steps: An X-shaped bevel is machined on the welding section of the stainless steel composite plate at the position corresponding to the base material layer, and a blunt edge is provided in the middle of the X-shaped bevel; a trapezoidal bevel is opened on the welding section of the stainless steel composite plate at the position corresponding to the transition layer and the stainless steel composite layer. Submerged arc welding is used to weld the substrate layer; The transition layer is welded using a stainless steel welding wire that matches the stainless steel cladding layer, employing dual tungsten inert gas (TIG) welding: the welding voltage is controlled at 14-15V, the welding current at 360-420A, the welding speed at 300-340mm / min, the wire feed speed at 4.6-5.0m / min, and the gap between the two tungsten electrodes is 0.5-1.5mm. Welding of stainless steel cladding layers using dual tungsten inert gas (TIG) welding: Use stainless steel welding wire that matches the stainless steel cladding layer, control the welding voltage at 14-15V, the welding current at 360-420A, the welding speed at 300-340mm / min, the wire feed speed at 4.6-5.0m / min, and the gap between the two tungsten electrodes at 0.5-1.5mm.

2. The high-quality welding method for stainless steel composite plates as described in claim 1, characterized in that, The angle between the inclined part and the vertical direction of the X-shaped bevel is the same as the angle between the inclined part and the vertical direction of the trapezoidal bevel.

3. The high-quality welding method for stainless steel composite plates as described in claim 2, characterized in that, The angle between the inclined part and the vertical direction of the X-shaped bevel and the angle between the inclined part and the vertical direction of the trapezoidal bevel are both α≥(1.5b1)°, where b1 represents the distance between the surface of the substrate layer and its interface with the stainless steel composite layer, and its unit parameter is mm.

4. The high-quality welding method for stainless steel composite plates as described in claim 1, characterized in that, The thickness b3 of the blunt edge at the middle of the X-shaped bevel is 2-4 mm.

5. The high-quality welding method for stainless steel composite plates as described in claim 1, characterized in that, The single-side width w2 of the trapezoidal bevel step is greater than or equal to (2 + 0.1b1), where b1 represents the distance between the surface of the substrate layer and the interface between it and the stainless steel composite layer, and its unit parameter is mm.

6. The high-quality welding method for stainless steel composite plates as described in claim 1, characterized in that, The distance w1 between the stepped plane of the trapezoidal bevel and the interface between the substrate layer and the stainless steel composite layer is controlled within the range of 0.5b2 to 0.8b2, where b2 represents the distance from the surface of the stainless steel composite layer to its interface with the substrate layer, and its unit parameter is mm.

7. The high-quality welding method for stainless steel composite plates as described in claim 1, characterized in that, In the step of welding the substrate layer using submerged arc welding: use carbon steel welding wire that matches the substrate layer, control the welding current to be 400-600A, the welding voltage to be 25-35V, and the welding speed to be 0.5-1.0m / min.

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