A method for producing a welded pipe of a zinc-based plated steel sheet

Abstract

The application relates to a preparation method of a zinc-based plated steel pipe welded tube, and the method comprises the following steps: heating the edges of a formed zinc-based plated steel plate; using an oxygen-containing gas with a set oxygen content and a set pressure to blow the outer plated edge area of the formed zinc-based plated steel plate in a heated state, so that the liquid zinc of the outer plated edge area is oxidized, and the edges of the formed zinc-based plated steel plate are closed to each other in an extrusion welding mode to form a weld, so that a zinc-based plated steel pipe welded tube is obtained; wherein the outer plated edge area comprises a region with a temperature greater than a plating melting point. The application reduces the cracking of the zinc-based plated steel pipe welded tube.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding, in particular to a preparation method of a zinc-based plated steel pipe. BACKGROUND

[0002] The zinc-based plated steel plate has become a high-end product in the fields of photovoltaic and highway guardrails.

[0003] The support structures such as photovoltaic support shafts, transmission shafts and high-speed guardrail columns all use high-frequency induction welded pipes, and when the zinc-based plated steel plate is welded, liquid zinc is easy to penetrate into the welding heat-affected zone, forming a liquid metal brittle crack, which causes the welded pipe to crack. At the same time, after the plated steel plate is treated by a scraper after high-frequency induction heating, the corrosion resistance of the weld and the surrounding area is difficult to guarantee. SUMMARY

[0004] The present application provides a preparation method of a zinc-based plated steel pipe, to solve the technical problem of how to reduce the cracking of the zinc-based plated steel pipe.

[0005] In a first aspect, the present application provides a preparation method of a zinc-based plated steel pipe, which comprises:

[0006] heating the edges of the formed zinc-based plated steel plate;

[0007] sweeping the outer plating edge area of the formed zinc-based plated steel plate in a heated state with an oxygen-containing gas with a set oxygen content and a set pressure, so that the liquid zinc in the outer plating edge area is oxidized, and the edges of the formed zinc-based plated steel plate are closed to each other to form a weld by extrusion welding, to obtain a zinc-based plated steel pipe; wherein the outer plating edge area includes a region with a temperature greater than the plating melting point.

[0008] Optionally, the set oxygen content is ≥5% by volume.

[0009] Optionally, the set oxygen content is 15% by volume to 90% by volume.

[0010] Optionally, the set pressure is >2MPa.

[0011] Optionally, the set pressure is 5MPa to 100MPa.

[0012] Optionally, the sweeping the outer plating edge area of the formed zinc-based plated steel plate in a heated state with an oxygen-containing gas with a set oxygen content and a set pressure, so that the liquid zinc in the outer plating edge area is oxidized, and the edges of the formed zinc-based plated steel plate are closed to each other to form a weld by extrusion welding, to obtain a zinc-based plated steel pipe, comprises:

[0013] The outer plating edge region of the shaped zinc-based plating steel plate in a heated state is purged with an oxygen-containing gas with a set oxygen content and a set pressure to oxidize the liquid zinc of the outer plating edge region, and the edges of the shaped zinc-based plating steel plate are closed to each other to form a weld bead by means of extrusion welding, to obtain a zinc-based plating steel plate welded pipe; wherein the welding speed of the extrusion welding is obtained from the set pressure, and the welding speed and the set pressure satisfy the following relationship: V≤P≤5V, V represents the welding speed, and P represents the set pressure.

[0014] Optionally, the shaped zinc-based plating steel plate comprises a steel base body and a zinc-based plating layer, and the zinc-based plating layer comprises one of the following: a pure zinc plating layer, a zinc-aluminum plating layer, a zinc-aluminum-magnesium plating layer, and a zinc-iron alloy plating layer.

[0015] Optionally, the method further comprises:

[0016] The surface burrs of the weld bead are scraped off, and then the damaged region of the plating layer is sprayed.

[0017] Optionally, the scraping temperature is >400℃.

[0018] Optionally, the spraying temperature is >200℃.

[0019] Compared with the prior art, the above technical solutions provided by the embodiments of the present application have the following advantages:

[0020] The preparation method of the zinc-based plating steel plate welded pipe provided by the embodiments of the present application melts the edges of the shaped zinc-based plating steel plate by heating, and pressure welds under the action of extrusion to prepare a zinc-based plating steel plate welded pipe; the outer plating edge region (a region with a temperature greater than the melting point of the plating layer is prone to zinc-induced LME cracking) of the shaped zinc-based plating steel plate in a heated state is purged with an oxygen-containing gas with a set oxygen content and a set pressure, which can increase the surface plating temperature of the welded shaped zinc-based plating steel plate, accelerate plating combustion, and convert liquid plating into solid matter; at the same time, it promotes the generation of AlFe3 and AlFe phases between the plating elements and the base body to isolate the liquid plating, modifies the surface of the to-be-welded region, continuously promotes the combustion or oxidation of the liquid zinc in this region, and separates the zinc powder from the surface of the steel plate in the form of oxidized zinc powder, thereby eliminating the liquid zinc element before extrusion welding, realizing the absence of liquid zinc in the 3 times plate thickness region of the weld bead of the zinc-based plating steel plate welded pipe, inhibiting the generation of zinc-induced LME cracks, and greatly reducing the cracking rate of the welded pipe. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, for those of ordinary skill in the art, based on the drawings, other drawings can be obtained without creative labor.

[0023] Figure 1 A flowchart of a preparation method of a zinc-based plated steel pipe welded pipe according to some embodiments of the present application is shown.

[0024] Figure 2 A picture of a welded pipe of a zinc-based plated steel pipe after welding according to some comparative examples of the present application is shown.

[0025] Figure 3 A picture of a welded pipe of a zinc-based plated steel pipe after welding according to some embodiments of the present application is shown.

[0026] Figure 4 A picture of a cracking of a flaring experiment of a zinc-based plated steel pipe welded pipe according to some comparative examples of the present application is shown.

[0027] Figure 5 A picture of a non-cracking of a flaring experiment of a zinc-based plated steel pipe welded pipe according to some embodiments of the present application is shown.

[0028] Figure 6 A picture of a non-cracking of a flattening experiment of a zinc-based plated steel pipe welded pipe according to some embodiments of the present application is shown.

[0029] Figure 7 A picture of a welded pipe of a zinc-based plated steel pipe after spraying according to some comparative examples of the present application is shown. DETAILED DESCRIPTION

[0030] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0031] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0032] In this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0033] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0034] Figure 1 For a flowchart illustrating a method for preparing a zinc-based coated steel sheet welded pipe according to some embodiments of this application, please refer to [link / reference]. Figure 1 This application provides a method for preparing zinc-based coated steel sheet welded pipe, the method comprising:

[0035] S1. Heating the edges of the formed zinc-based coated steel sheet;

[0036] S2. Using oxygen-containing gas with a set oxygen content and a set pressure, the outer edge area of ​​the molded zinc-based coated steel sheet in a heated state is purged to oxidize the liquid zinc in the outer edge area. The edges of the molded zinc-based coated steel sheet are then closed together by extrusion welding to form a weld bead, resulting in a welded pipe made of zinc-based coated steel sheet. The outer edge area includes a region with a temperature higher than the melting point of the coating.

[0037] In some embodiments, the set oxygen content is ≥5% by volume.

[0038] In some embodiments, the set oxygen content is 15% to 90% by volume.

[0039] In some implementations, the set pressure is >2 MPa.

[0040] In some embodiments, the set pressure is 5 MPa to 100 MPa.

[0041] In some embodiments, the high-pressure gas can quickly drive water vapor away from the welding area, and can increase the welding temperature (the lubricant aqueous solution is applied during the pressure process), the oxygen-containing gas can increase the welding surface temperature, accelerate the coating combustion, and convert the liquid into solid matter; at the same time, the oxygen-containing gas can promote the formation of AlFe3 and AlFe phases between the coating elements and the substrate to isolate the liquid coating, and achieve the surface modification of the area to be welded; the oxygen-containing gas can oxidize the edges of the steel strip, reduce the adhesion between the coating and the substrate, and facilitate the removal of the coating elements; the surface of the area to be welded is extruded by AlFe3, Fe2O3 and residual zinc oxide to form an effective connection, and the zinc oxide formed by combustion is driven away from the surface of the workpiece to be welded by the high-pressure gas. By limiting the oxygen content in the oxygen-containing gas, the combustion can be quickly assisted, the surface temperature can be increased, and the zinc can be burned in the combustion-supporting gas to form the combustion product zinc oxide; by limiting the pressure of the oxygen-containing gas, the evaporation of liquid water and the removal of the surface zinc oxide can be achieved. The high-pressure oxygen-containing gas can be compressed air, which has low investment cost. The high-pressure oxygen-containing gas blowing area is greater than the melting point of the coating, which can continuously promote the combustion of liquid zinc or be oxidized to separate from the surface of the steel plate in the form of zinc oxide powder, thereby eliminating the liquid zinc element before welding, inhibiting the generation of zinc-induced LME cracks, and greatly reducing the cracking rate of the welded pipe. For example, the above-mentioned set oxygen content can be 5%, 6%, 7%, 8%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and the like, and further, the above-mentioned set oxygen content can be 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and the like. The above-mentioned set pressure can be 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa and the like, and further, the above-mentioned set pressure can be 5 MPa, 6 MPa, 7 MPa, 8 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa and the like.

[0042] In some embodiments, the above-mentioned set pressure can be 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa and the like, and further, the above-mentioned set pressure can be 5 MPa, 6 MPa, 7 MPa, 8 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa and the like.

[0043] The outer plating edge region of the shaped zinc-based plating steel plate in a heated state is purged with an oxygen-containing gas with a set oxygen content and a set pressure to oxidize the liquid zinc of the outer plating edge region, and the edges of the shaped zinc-based plating steel plate are closed to each other to form a weld by extrusion welding, to obtain a zinc-based plating steel plate welded pipe; wherein the welding speed of the extrusion welding is obtained from the set pressure, and the welding speed and the set pressure satisfy the following relationship: V≤P≤5V, V represents the welding speed, and P represents the set pressure.

[0044] In the embodiments of the present application, the welding speed and the set pressure satisfy V≤P≤5V, which can effectively promote the formation and removal of zinc oxide and inhibit the brittle crack of liquid metal.

[0045] In some embodiments, the shaped zinc-based plating steel plate comprises a steel base and a zinc-based plating layer, and the zinc-based plating layer comprises one of the following: a pure zinc plating layer, a zinc-aluminum plating layer, a zinc-aluminum-magnesium plating layer, and a zinc-iron alloy plating layer.

[0046] In the embodiments of the present application, the zinc-based plating layer in the shaped zinc-based plating steel plate can be one of a pure zinc plating layer, a zinc-aluminum plating layer, a zinc-aluminum-magnesium plating layer, and a zinc-iron alloy plating layer.

[0047] In some embodiments, the method further comprises:

[0048] S3, the surface burrs of the weld are scraped, and then the damaged area of the plating layer is sprayed.

[0049] In some embodiments, the scraping temperature is >400℃.

[0050] In some embodiments, the spraying temperature is >200℃.

[0051] In the embodiments of the present application, the steel strip is extruded by the extrusion roller to extrude the oxide and form a weld connection, and after the burrs are scraped, the surface of the weld (at least including the outer surface of the weld) and the damaged area of the plating layer are sprayed to ensure the quality and corrosion resistance of the weld. By limiting the scraping temperature, the welding burrs can be effectively scraped, and the scraped area is flat. For example, the scraping temperature can be 401℃, 405℃, 410℃, 420℃, 425℃, 430℃, etc. By limiting the spraying temperature, the bonding force between the sprayed layer and the weld area and the heat affected zone is high, and the sprayed layer is not easy to fall off, so as to improve the corrosion resistance of the weld. For example, the spraying temperature can be 201, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, etc. The spraying material contains one of zinc and aluminum elements, the spraying material is a wire material, the diameter is 0.6mm-6mm, and the spraying thickness is greater than 20μm.

[0052] In summary, the content of the application solves the problems of heat affected zone cracking in high frequency induction welding and insufficient corrosion resistance of the weld of the zinc-based plated steel plate welded pipe, has low cost, and the yield can reach the level of non-plated steel plate, and the local corrosion resistance of the weld can be ensured to guarantee the overall corrosion resistance of the welded pipe.

[0053] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not to limit the scope of the application. The experimental methods in the following examples without specific conditions are generally determined according to national standards. If there is no corresponding national standard, the general international standard, conventional conditions, or the conditions suggested by the manufacturer are used.

[0054] The embodiment of the application provides a preparation method of a zinc-based plated steel plate welded pipe. Please refer to the material parameters of the zinc-based plated steel plate welded pipe shown in Table 1, and the process parameters of the zinc-based plated steel plate welded pipe shown in Table 2.

[0055] Table 1 Material parameters of the zinc-based plated steel plate welded pipe

[0056]

[0057] Table 2 Process parameters of the zinc-based plated steel plate welded pipe in blowing and welding

[0058]

[0059]

[0060] The welding results of the zinc-based plated steel plate welded pipes prepared in Examples 1-6 and Comparative Examples 1-6 are evaluated, and the evaluation results are shown in Table 3.

[0061] Table 3 Evaluation results of the welding of the zinc-based plated steel plate welded pipe

[0062] Serial number Welding condition Example 1 Good Example 2 Good Example 3 Good Example 4 Good Example 5 Good Example 6 Good Comparative Example 1 Cracking Comparative Example 2 Cracking Comparative Example 3 Cracking Comparative Example 4 Cracking Comparative Example 5 Cracking Comparative Example 6 Cracking

[0063] Table 4 Evaluation results of the zinc-based plated steel plate welded pipe in burr scraping, spraying and corrosion resistance

[0064]

[0065] Table 5 Phase composition on the surface of the welding heat affected zone of a zinc-based plated steel plate welded pipe provided by a comparative example

[0066] Phase Proportion AlFe3 30.27％ Mg2Zn 11 ]]> 28.18％ Zn 14.38％ Al 13.83％ (Mg 0.4 Al 0.6 )Al 1.8 O4]]> 12.71％ MgZn2 0.63％

[0067] Table 6 Phase composition on the surface of the welding heat affected zone of a zinc-based plated steel plate welded pipe provided by an embodiment

[0068]

[0069]

[0070] Figure 2 A picture of the surface of the weld after deburring of a welded pipe of a zinc-based plated steel plate according to some examples of the present application; see Figure 2 , indicating that cracking occurs in the heat-affected zone of the weld, reducing the weld strength. Figure 3 A picture of the surface of the weld after deburring of a welded pipe of a zinc-based plated steel plate according to some examples of the present application; see Figure 3 , indicating that no cracking occurs in the heat-affected zone of the weld, meeting the weld strength requirements. Figure 4 A picture of the cracking of a flaring experiment of a welded pipe of a zinc-based plated steel plate according to some examples of the present application; see Figure 4 , indicating that cracking occurs in the heat-affected zone of the weld, and cracking occurs in the heat-affected zone using the flaring experiment. Figure 5 A picture of the non-cracking of a flaring experiment of a welded pipe of a zinc-based plated steel plate according to some examples of the present application; see Figure 5 , indicating that no cracking occurs in the heat-affected zone of the weld, and no cracking occurs in the weld and base material using the flaring experiment, meeting the weld strength requirements. Figure 6 A picture of the non-cracking of a flattening experiment of a welded pipe of a zinc-based plated steel plate according to some examples of the present application; see Figure 6 , indicating that no cracking occurs in the heat-affected zone of the weld, and no cracking occurs in the weld and base material using the flattening experiment. Table 5 shows the surface phase composition of the heat-affected zone of a welded pipe of a zinc-based plated steel plate according to some examples of the present application; indicating that there is still a large amount of liquid zinc on the welding surface, which can still cause liquid metal cracking; Table 6 shows the surface phase composition of the heat-affected zone of a welded pipe of a zinc-based plated steel plate according to some examples of the present application, indicating that there is no liquid zinc on the welding surface, which will not cause liquid metal cracking, thereby ensuring the weld strength; Figure 7 A picture of the surface of the weld after spraying of a welded pipe of a zinc-based plated steel plate according to some examples of the present application; see Figure 7 , indicating that there is no plated element in the welding area, and the surface needs to be sprayed to ensure corrosion resistance, according to Table 4, indicating that the zinc-based plated steel plate welded pipe after spraying has good corrosion resistance.

[0071] The foregoing detailed description of the application has been presented for purposes of illustration and description. Various modifications and changes can be made to these embodiments without departing from the spirit and scope of the application. It is intended that the scope of the application should not be limited by the particular representative embodiments described above.

Claims

1. A method for preparing a zinc-based coated steel plate welded pipe, characterized in that, The method includes: The edges of the formed zinc-based coated steel sheet are heated; An oxygen-containing gas with a set oxygen content and pressure is used to purge the outer edge region of the heated shaped zinc-based coated steel sheet. This oxidizes the liquid zinc in the outer edge region into zinc oxide, while simultaneously promoting the formation of AlFe3 and AlFe phases between the coating elements and the substrate to isolate the liquid coating. The edges of the shaped zinc-based coated steel sheet are then closed together by extrusion welding to form a weld bead, resulting in a welded pipe made of zinc-based coated steel sheet. The outer edge region includes areas with a temperature higher than the melting point of the coating. The set oxygen content is 60% to 90% by volume, and the set pressure is 5 MPa to 100 MPa. The welding speed of the extrusion welding is obtained from the set pressure, and the welding speed and the set pressure satisfy the following relationship: V ≤ P ≤ 5V, where V represents the welding speed and P represents the set pressure.

2. The method according to claim 1, characterized in that, The formed zinc-based coated steel sheet includes a steel substrate and a zinc-based coating, wherein the zinc-based coating includes one of the following: pure zinc coating, zinc-aluminum coating, zinc-aluminum-magnesium coating, and zinc-iron alloy coating.

3. The method according to claim 1, characterized in that, The method further includes: The surface burrs of the weld bead are scraped off, and then the damaged areas of the coating are sprayed.

4. The method according to claim 3, characterized in that, The scraping temperature is >400℃.

5. The method according to claim 3, characterized in that, The spraying temperature is >200℃.

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