Butt welding method for S31803 duplex stainless steel pipes

Abstract

The invention provides a butt welding method for S31803 duplex stainless steel pipes. The butt welding method comprises the steps that S10, a single-side V-shaped groove is formed in the welding face of each S31803 duplex stainless steel pipe; s20, the two S31803 duplex stainless steel pipes are positioned and in butt joint, and a gap is formed between the two welding faces; s30, welding treatment is carried out between the two welding faces, and the welding treatment comprises the steps that backing welding is carried out through a TIG welding technology, so that a backing welding layer is formed between the two welding faces; and a middle welding layer and a cosmetic welding layer are sequentially formed on the backing welding layer through an FCAW welding process. According to the butt welding method for the S31803 duplex stainless steel pipes, the butt welding efficiency of the S31803 duplex stainless steel pipes can be improved, the welding cost and the labor intensity of welders are reduced, and meanwhile the mechanical property of a welding joint between the S31803 duplex stainless steel pipes can be improved.

Description

Technical Field

[0001] The invention generally relates to the technical field of ships, and in particular to a butt welding method for a S31803 duplex stainless steel pipe. Background Art

[0002] Compared with ordinary austenitic stainless steel, S31803 duplex stainless steel has better corrosion resistance, making it a common material for ship engine room pipelines. At present, the butt welding between S31803 duplex stainless steel pipes usually adopts TIG welding process, which has at least the following problems:

[0003] 1. The butt welding time is long, which makes the butt welding efficiency low, and then leads to high butt welding cost between S31803 duplex stainless steel pipes;

[0004] 2. The mechanical properties of the welded joints formed by welding are general, which can hardly meet the demand for high-performance welded joints in ship engine room piping. Summary of the invention

[0005] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a butt welding method for S31803 duplex stainless steel pipe.

[0006] The present application provides a butt welding method for a S31803 duplex stainless steel pipe, comprising:

[0007] S10: A single-sided V-shaped groove is formed on the welding surface of each S31803 duplex stainless steel pipe;

[0008] S20: Position and butt two S31803 duplex stainless steel pipes, with a gap between the two welding surfaces;

[0009] S30: Perform welding process between two welding surfaces, the welding process includes:

[0010] Performing root welding by TIG welding process to form a root welding layer between two welding surfaces;

[0011] The intermediate welding layer and the cover welding layer are sequentially welded on the base welding layer through the FCAW welding process.

[0012] Furthermore, the filler material in the TIG welding process is ER2209 welding wire, and the filler material in the FCAW welding process is ER2209T1-1 welding wire.

[0013] Furthermore, the spacing is 2 mm, and the groove angle of the single-sided V-groove is 30°. In the TIG welding process, the diameter of the ER2209 welding wire is 2.0 mm, the welding heat input is 0.45-0.75 KJ / mm, the welding current is 80 A, the welding voltage is 11 V, the welding speed is 5.5 cm / min, the argon flow rate is 10-15 L / min, and the working electrode is DCEN.

[0014] Furthermore, in the FCAW welding process, the diameter of the ER2209T1-1 welding wire is 1.2 mm, the welding heat input is 0.5-2.5 KJ / mm, the welding current is 160 A, the welding voltage is 24 V, the welding speed is 7 cm / min, the argon gas flow rate is 15-20 L / min, and the working electrode is DCEP.

[0015] Further, during the welding process, the interlayer temperature is 120°C-140°C.

[0016] Furthermore, the weld in the base welding is formed in one pass.

[0017] Furthermore, the welding methods adopted for the middle welding layer and the cover welding layer are both separate pass welding.

[0018] Furthermore, between S10 and S30, the process also includes: cleaning the surface of each single-sided V-shaped groove and its surroundings, wherein the surface cleaning includes grinding and cleaning in sequence, wherein a deoxidizing cleaning agent is used in the cleaning process.

[0019] Furthermore, the arc extinction position is polished immediately after each welding is completed to remove welding defects existing at the arc extinction position, and the welding defects at least include thermal cracks and shrinkage cavities.

[0020] Further, before the base welding, the S31803 duplex stainless steel pipe is filled with argon gas.

[0021] The present application provides a butt welding method for a S31803 duplex stainless steel pipe, which combines a TIG welding process with a FCAW welding process, wherein the TIG welding process is used for base welding, and the FCAW welding process is used to sequentially weld an intermediate welding layer and a cover welding layer on the base welding layer, and specific welding process parameters are matched, which can not only improve the butt welding efficiency of the S31803 duplex stainless steel pipe, but also reduce the welding cost and the labor intensity of the welder, and at the same time can also improve the mechanical properties of the welded joints between the S31803 duplex stainless steel pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0023] Figure 1 A schematic flow chart of a butt welding method for a S31803 duplex stainless steel pipe provided in an embodiment of the present application;

[0024] Figure 2 A schematic diagram of a welding node provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0026] Please refer to the attached Figure 1 The embodiment of the present application provides a butt welding method for a S31803 duplex stainless steel pipe, which is used to butt weld two S31803 duplex stainless steel pipes together and form a welded joint at the weld.

[0027] The above-mentioned butt welding method comprises:

[0028] S10: A single-sided V-shaped groove is formed on the welding surface of each S31803 duplex stainless steel pipe;

[0029] S20: Position and butt two S31803 duplex stainless steel pipes, with a gap between the two welding surfaces;

[0030] S30: Perform welding process between two welding surfaces, the welding process includes:

[0031] Performing root welding by TIG welding process to form a root welding layer between two welding surfaces;

[0032] The intermediate welding layer and the cover welding layer are sequentially welded on the base welding layer through the FCAW welding process.

[0033] Compared with the TIG welding process, the FCAW welding process has a faster welding speed, improved welding efficiency, and better welding quality. In this embodiment, by combining the TIG welding process and the FCAW welding process, the TIG welding process is used for base welding, and the FCAW welding process is used to sequentially weld the base welding layer to form an intermediate welding layer and a cover welding layer, which can not only improve the butt welding efficiency of the S31803 duplex stainless steel pipe, but also reduce the welding cost and the labor intensity of the welder, and at the same time, can also improve the mechanical properties of the welded joint.

[0034] Among them, two welding surfaces located on both sides of the weld are provided with single-sided V-shaped grooves. In this welding method, a single-sided welding and double-sided forming method is adopted at the weld, which can improve the welding efficiency.

[0035] Among them, through the above-mentioned positioning and docking, the S31803 duplex stainless steel pipe can be accurately installed at the set welding position, avoiding the axial misalignment between the S31803 duplex stainless steel pipes.

[0036] Preferably, the filler material in the TIG welding process is ER2209 welding wire, and the filler material in the FCAW welding process is ER2209T1-1 welding wire. By using the above-mentioned adapted solder, the mechanical properties and corrosion resistance of the welded joint are high.

[0037] Preferably, between S10 and S30, the process further includes: cleaning the surface of each single-sided V-groove and its surroundings, wherein the surface cleaning includes a grinding process and a cleaning process performed in sequence, wherein a deoxidizing cleaning agent is used in the cleaning process. The above grinding process can remove the oxidation color on the single-sided V-groove and its surrounding surface. The cleaning process can remove impurities such as grease, moisture, etc. in the grinding area. Compared with existing austenitic stainless steel, the S31803 duplex stainless steel pipe is more sensitive to moisture on the joint surface. Removing moisture on the joint surface by a deoxidizing cleaning agent helps to improve the quality of the butt joint. The deoxidizing cleaning agent is, for example, but not limited to, ethanol or propanol.

[0038] Preferably, the weld in the base welding is formed in one step, avoiding the influence of multiple heating and cooling on the weld, and significantly improving the quality of the base weld.

[0039] Preferably, the welding method used for the middle welding layer and the cover welding layer is split welding, that is, the middle welding layer and the cover welding layer are divided into several sections for welding, which helps to reduce the welding deformation of the middle welding layer and the cover welding layer and improve the quality of the butt weld.

[0040] Preferably, the arc extinction position is polished immediately after each welding (e.g., base welding, intermediate welding layer, and cap welding layer) to remove welding defects existing at the arc extinction position, and the welding defects include at least thermal cracks and shrinkage cavities. Since the penetration depth of S31803 duplex stainless steel is relatively shallow, the above welding defects cannot be melted and eliminated in the subsequent welding process. The above grinding treatment is used to remove welding defects to avoid the above welding defects affecting the quality of subsequent welding layers, thereby ensuring the quality of the welded joint. In addition, after welding, the weld can be subjected to quality inspections such as X-ray inspection, color flaw detection, or magnetic particle inspection to inspect the quality of the interior and surface of the weld.

[0041] Preferably, before the base welding, the S31803 duplex stainless steel pipe is filled with argon to ensure the welding quality.

[0042] Preferably, after positioning and butting, the two S31803 duplex stainless steel pipes can be tack welded. When the subsequent welds encounter tack welds, the tack welds need to be removed to avoid the tack welds affecting the weld quality.

[0043] Preferably, the spacing between the two welding surfaces is 2-4mm, the groove angle of the single-sided V-shaped groove is 30°, and the blunt edge is 2mm, that is, the single-sided V-shaped double-sided groove angle is 60°. In the welding process, the interlayer temperature is 120℃-140℃. In the TIG welding process, the diameter of the ER2209 welding wire is 2.0mm, the welding heat input is 0.45-0.75KJ / mm, the welding current is 80A, the welding voltage is 11V, the welding speed is 5.5cm / min, the argon flow rate is 10-15L / min, and the working electrode is DCEN; in the FCAW welding process, the diameter of the ER2209T1-1 welding wire is 1.2mm, the welding heat input is 0.5-2.5KJ / mm, the welding current is 160A, the welding voltage is 24V, the welding speed is 7cm / min, the argon flow rate is 15-20L / min, and the working electrode is DCEP. Based on the combination of TIG welding process and FCAW welding process, the configuration of the above-mentioned specific welding process parameters, and the cleaning of the welding surface, the welding efficiency of S31803 duplex stainless steel pipe is improved, the butt welding cost and the labor intensity of welders are reduced, and the tensile strength, plasticity, toughness and other mechanical properties of the welded joints between S31803 duplex stainless steel pipes are also improved.

[0044] Please refer to the attached Figure 2 Taking two S31803 duplex stainless steel pipes with a diameter of 219 mm, a length of 150 mm and a thickness of 10 mm as an example, the groove angle of the single-sided V-groove is 30° and the spacing is 2 mm. Through the above welding process, the tensile strength, plasticity, toughness and other mechanical properties of the welded joint are equivalent to those of the S31803 duplex stainless steel pipe.

[0045] The butt welding method of the S31803 duplex stainless steel pipe provided in the present application, by combining the TIG welding process and the FCAW welding process and matching specific welding process parameters, can not only improve the butt welding efficiency of the S31803 duplex stainless steel pipe, but also reduce the welding cost and the labor intensity of the welder, and at the same time can also improve the mechanical properties of the welded joints between the S31803 duplex stainless steel pipes.

[0046] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A butt welding method for S31803 duplex stainless steel pipe, characterized in that: include: S10: A single-sided V-shaped groove is formed on the welding surface of each S31803 duplex stainless steel pipe; S20: Positioning and butting the two S31803 duplex stainless steel pipes, with a spacing between the two welding surfaces; S30: performing a welding process between the two welding surfaces, the welding process comprising: Performing bottom welding by TIG welding process to form a bottom welding layer between the two welding surfaces; The intermediate welding layer and the cover welding layer are sequentially welded on the base welding layer through the FCAW welding process.

2. The butt welding method of S31803 duplex stainless steel pipe according to claim 1, characterized in that: The filler material in the TIG welding process is ER2209 welding wire, and the filler material in the FCAW welding process is ER2209T1-1 welding wire.

3. The butt welding method of S31803 duplex stainless steel pipe according to claim 2, characterized in that: The spacing is 2mm, and the groove angle of the single-sided V-groove is 30°. In the TIG welding process, the diameter of the ER2209 welding wire is 2.0mm, the welding heat input is 0.45-0.75KJ / mm, the welding current is 80A, the welding voltage is 11V, the welding speed is 5.5cm / min, the argon gas flow rate is 10-15L / min, and the working electrode is DCEN.

4. The butt welding method of S31803 duplex stainless steel pipe according to claim 3, characterized in that: In the FCAW welding process, the diameter of the ER2209T1-1 welding wire is 1.2 mm, the welding heat input is 0.5-2.5 KJ / mm, the welding current is 160 A, the welding voltage is 24 V, the welding speed is 7 cm / min, the argon gas flow rate is 15-20 L / min, and the working electrode is DCEP.

5. The butt welding method of S31803 duplex stainless steel pipe according to claim 1, characterized in that: In the welding process, the interpass temperature is 120°C-140°C.

6. The butt welding method of S31803 duplex stainless steel pipe according to claim 1, characterized in that: The weld in the base welding is formed in one step.

7. The butt welding method of S31803 duplex stainless steel pipe according to claim 1, characterized in that: The welding methods adopted by the middle welding layer and the cover welding layer are both separate pass welding.

8. The butt welding method of S31803 duplex stainless steel pipe according to claim 1, characterized in that: The process between S10 and S30 also includes: performing surface cleaning on each of the single-sided V-shaped grooves and the surrounding areas thereof, wherein the surface cleaning includes grinding and cleaning in sequence, wherein a deoxidizing cleaning agent is used in the cleaning process.

9. The butt welding method of S31803 duplex stainless steel pipe according to claim 1, characterized in that: The arc extinction position is polished immediately after each welding is completed to remove welding defects existing at the arc extinction position, wherein the welding defects at least include thermal cracks and shrinkage cavities.

10. The butt welding method of S31803 duplex stainless steel pipe according to claim 1, characterized in that: Before the base welding, the S31803 duplex stainless steel pipe is filled with argon.

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