A head heat treatment forming method

Abstract

The present invention discloses a head heat treatment forming method, which belongs to the field of hot forming welding technology, and comprises the following steps: welding the weld of the base layer; embedding a lining plate in the weld of the cladding and fixing the lining plate to the cladding; hot forming and pressing the head; removing the lining plate and welding the weld of the cladding; in the present invention, when the head is hot formed, a lining plate embedded in the weld of the cladding is used to replace the traditional cladding weld. After the head is hot formed, the lining plate can be conveniently removed and the weld at the cladding can be repaired, so that the intergranular corrosion resistance of the cladding will not decrease. At the same time, the lining plate is not a disposable item and can be reused, and there is no need to use double welding materials at the weld of the cladding, which effectively saves costs, and the operation is simple and quick, and no excessive grinding and welding processes are required.

Description

Technical Field

[0001] The invention relates to the technical field of thermoforming welding, and in particular to a head heat treatment forming method. Background Art

[0002] Intergranular corrosion is a type of corrosion that extends inward along the interface between metal grains. Due to the difference in chemical composition between the surface and interior of the grains and the presence of impurities or internal stress at the grain boundaries, intergranular corrosion will destroy the bonding between the grains and greatly reduce the mechanical strength of the metal. Moreover, after corrosion occurs, the surface of the metal and alloy still maintains a certain metallic luster and no signs of damage can be seen. However, the bonding force between the grains is significantly weakened, the mechanical properties deteriorate, and it cannot withstand knocking. Therefore, it is a very dangerous corrosion that usually occurs in brass, hard aluminum alloys and some stainless steels and nickel-based alloys. Intergranular corrosion of stainless steel welds is a major problem in the chemical industry.

[0003] When performing welding evaluation on the hot forming of nickel-based composite plate heads for pressure vessels, intergranular corrosion failures often occur and need to be repaired. To avoid this, the existing solution is to weld the cladding weld before hot forming the head and then remove the cladding weld layer after hot forming the head. Specifically, the cladding is directly welded after welding the base layer, and after hot forming, the weld at the cladding is ground off and then the weld at the cladding is repaired, so that the weld at the cladding in contact with the medium does not undergo normalizing and annealing, and the problem of intergranular corrosion is also solved. However, this solution requires the use of double welding materials at the weld of the cladding and requires personnel to grind inside the head. Not only is the operation difficult and there are safety hazards, but it also requires secondary welding, which wastes welding materials and manpower. The waste of manpower and material resources is serious, which is not in line with the concept of sustainable development and is unacceptable from a cost perspective.

[0004] Therefore, developing and designing a head heat treatment forming method that can effectively solve the intergranular corrosion problem, save costs, and is simple and quick to operate is an issue that needs to be urgently addressed at this stage. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a head heat treatment forming method. During the head heat forming, a lining plate embedded in the weld of the cladding is used to replace the traditional cladding weld. After the head is heat formed, the lining plate is removed and the cladding is repaired by welding, so that the intergranular corrosion resistance of the cladding will not be reduced. The lining plate can be reused, and there is no need to use double welding materials at the weld of the cladding, which effectively saves costs and is simple and quick to operate.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a head heat treatment forming method, which is applied to a head having a base layer and a coating, wherein the coating is attached to the base layer, and is characterized in that it comprises the following steps:

[0008] S1: welding the weld of the base layer;

[0009] S2: embedding a lining plate into the weld of the cladding and fixing the lining plate to the cladding;

[0010] S3: hot forming and pressing the head;

[0011] S4: Remove the lining plate and weld the weld of the cladding.

[0012] As a preferred technical solution, before step S2, the dimensions of the cladding and the grooves on the head are measured, and a lining plate capable of covering the weld of the head is processed.

[0013] As a preferred technical solution, in step S2, the lining plate is fixed to the weld of the covering by spot welding, and the welding current of the spot welding is set to 70-170A, the welding voltage is set to 10-18V, the welding speed is set to 50-200mm / min, and the interlayer temperature is not higher than 150℃.

[0014] As a preferred technical solution, the base layer is made of carbon steel;

[0015] And / or, the coating is made of nickel-based alloy.

[0016] As a preferred technical solution, the groove on the head is set as a V-shaped inner groove, the blunt edge of the V-shaped inner groove is set to 2-3 mm, the gap is set to 0-2 mm, and the angle is set to 53-57°; the single-side peeling width of the coating is set to 4-6 mm;

[0017] And / or, the method of welding the weld of the base layer is set to SAW; the welding material is set to a welding wire with a diameter of 4.0 mm, and the material of the welding material is set to F55P3-EF3; the welding current is set to 400-670A, the welding voltage is set to 26-38V, and the welding speed is set to 400-600mm / min.

[0018] As a preferred technical solution, the material of the lining plate is set to stainless steel or nickel-based alloy;

[0019] And / or, the lining plate is in the shape of a long strip, and the length L of the lining plate is set to , the width B of the lining plate is set to , the thickness T of the lining plate is set to , where D1 is the diameter of the head before forming, D2 is the shortest distance between the joint of the head and its center, B1 is the single-side peeling width of the coating, B2 is the gap of the V-shaped inner groove, and T1 is the thickness of the coating;

[0020] And / or, the shape of the lining plate matches the shape of the weld of the cladding.

[0021] As a preferred technical solution, in step S3, the head is hot-formed and pressed at least twice; during the first hot-forming pressing, the furnace temperature is not greater than 800°C, the holding temperature is set to 890-950°C, the holding time is set to 40-80min, and the final pressing temperature is set to 820-880°C; during the subsequent hot-forming pressing, the holding temperature is set to 890-950°C, the holding time is set to 20-40min, and the final pressing temperature is set to 820-880°C; after the last hot-forming pressing, the head is air-cooled.

[0022] As a preferred technical solution, in step S4, the spot welding points are polished and the lining plate is removed.

[0023] As a preferred technical solution, the weld seam of the coating is welded by surfacing.

[0024] As a preferred technical solution, the head is set as a pressure vessel head.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. In the present invention, when the head is thermoformed, a lining plate embedded in the weld of the cladding is used to replace the traditional cladding weld. After the head is thermoformed, the lining plate can be easily removed and the weld of the cladding can be repaired, so that the intergranular corrosion resistance of the cladding will not be reduced. At the same time, the lining plate is not a disposable item and can be reused. It is no longer necessary to use double welding materials at the weld of the cladding, which saves the amount of welding materials for one welding. At the same time, compared with the existing method, the manpower for one welding and one grinding is saved, and the possible accidents during human operation are reduced. Taking a 2000mm long weld as an example, the cost of one welding plus one grinding plus one welding material consumption is more than one thousand yuan, which effectively saves costs and no longer requires too many grinding and welding processes. The process steps are simpler and more suitable for use by manufacturers and head manufacturers.

[0027] 2. In the present invention, when the head is thermoformed, the liner embedded in the weld of the cladding can also increase the structural strength of the weld, and the stress caused by the thin thickness of the weld at the base layer will not cause the head to crack. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1This is a process flow chart of an embodiment of a head heat treatment forming method of the present invention;

[0029] Figure 2 This is a schematic structural diagram of a head after welding the base weld in an embodiment of a head heat treatment forming method of the present invention;

[0030] Figure 3 This is a schematic structural diagram of the head after the liner and the cladding are fixed in one embodiment of the head heat treatment forming method of the present invention.

[0031] In the figure: 1-base layer, 2-covering layer, 3-liner. DETAILED DESCRIPTION

[0032] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings. Example 1

[0033] Please refer to Figure 1-Figure 3 , is an embodiment of a head heat treatment forming method provided by the present invention, applied to a head having a base layer 1 and a cladding layer 2, the head being a pressure vessel head, and the head being made of N06625 composite plate; the groove on the head is a V-shaped inner groove, the blunt edge of the V-shaped inner groove is set to 2-3mm, the gap is set to 2mm, the angle is set to 55°, and the groove gap is 2mm; the cladding layer 2 is attached to the base layer 1, the single-side peeling width of the cladding layer 2 is 10mm, the base layer 1 is made of SA516Gr70, and the cladding layer 2 is made of Ni6625, comprising the following steps:

[0034] S1: Welding the weld of the base layer 1. Specifically, the method for welding the weld of the base layer 1 is set to submerged arc welding. Submerged arc welding is automatic welding, which can significantly improve welding efficiency and is suitable for welding steel plates of various thicknesses, especially for welding plates with a thickness greater than 8 mm. The groove filling efficiency of submerged arc welding is significantly higher than that of argon arc welding or plasma welding. The welding speed of submerged arc welding is significantly better than manual welding, and the efficiency can be improved by 30%-50%. At the same time, submerged arc welding has a high degree of automation, and the operator only needs to control the welding machine, which reduces labor intensity and can effectively reduce medium- and long-term production costs. In addition, the welding process of submerged arc welding is stable, the weld is uniform and of high quality, the heat is evenly distributed during the welding process, which reduces welding stress and reduces welding deformation. Furthermore, submerged arc welding produces less smoke and harmful gases during the welding process, and has less pollution to the environment.

[0035] The welding consumables are set to be 4.0mm diameter welding wire, the material of the welding consumables is set to F55P3-EF3, and the use of welding wire for submerged arc welding can better control the composition and performance of the weld and ensure stable welding quality. The welding current is set to 400-670A, the welding voltage is set to 26-38V, and the welding speed is set to 400-600mm / min. The above welding parameters can ensure the consistency and quality of the weld, reduce the occurrence of defects such as pores and cracks, and can ensure the mechanical properties such as tensile strength, bending, and impact of the weld, as well as the performance of intergranular corrosion, while meeting the material properties and ensuring high welding efficiency.

[0036] Furthermore, due to the reduction of welding defects, the rework rate is reduced, thereby reducing material waste and labor costs. At the same time, stable welding parameters can avoid frequent adjustments by operators, allowing operators to focus more on the welding process, reducing operational difficulty, improving welding speed and overall production efficiency, and at the same time reducing the impact on welding equipment and extending the service life of the equipment;

[0037] Before step S2, it is also necessary to measure the size of the groove on the head and the coating 2, and then process the lining plate 3 that can cover the weld of the head; specifically, Figure 3 As shown, the lining plate 3 should be in the shape of a long strip, and the length L of the lining plate 3 is set to , the width B of the lining plate 3 is set to , the thickness T of the lining plate 3 is set to , where D1 is the diameter of the head before forming, D2 is the shortest distance between the head seam and its center, B1 is the single-side peeling width of the coating 2, B2 is the gap of the V-shaped inner groove, and T1 is the thickness of the coating 2; the liner 3 can effectively meet the requirements of covering the weld of the head at this size.

[0038] S2: Embed the lining plate 3 in the weld of the cladding 2 and fix the lining plate 3 to the cladding 2. The lining plate 3 can form a temporary cladding at the weld of the cladding 2.

[0039] Specifically, the material of the lining plate 3 is duplex stainless steel, specifically S31803 or S32205. The lining plate 3 is preferably spot-welded to the weld seam of the cladding 2 by tungsten inert gas arc welding. Nickel-based welding materials are used for spot welding. Compared with the method of welding the lining plate 3 to the weld seam of the cladding 2 and then removing it, spot welding saves more welding materials and can also make it easier to remove the lining plate 3. The head is a nickel-based composite plate head (N06625), preferably a nickel-based composite plate head. The thickness of the lining plate 3 is greater than 20 mm. The specific welding parameters are shown in Table 1.

[0040] Table 1 Spot welding parameters of nickel-based composite plate head liner

[0041]

[0042] Furthermore, the material of the lining plate 3 is set to carbon steel or stainless steel, and the lining plate 3 is preferably in the shape of a long strip. The shape of the lining plate 3 should match the shape of the weld of the cladding 2. When the lining plate 3 is fixed at the weld of the cladding 2, it can effectively increase the structural strength of the weld, and will not cause the head to crack due to the stress generated by the thin weld thickness of the base layer 1.

[0043] S3: Hot forming and pressing the head; the specific process is to first heat the circular plate used to form the head, then hoist the heated circular plate onto the workbench of the stamping machine, and use a punch to stamp it to achieve hot forming and pressing; it should be noted that the punch can be replaced according to the size of the circular plate;

[0044] Specifically, the head is hot formed and pressed 2-3 times; during the first hot forming pressing, the furnace temperature is not higher than 800°C, the holding temperature is set to 890-950°C, the holding time is set to 40-80min, and the final pressing temperature is set to 820-880°C; during the subsequent hot forming pressing, the holding temperature is set to 890-950°C, the holding time is set to 20-40min, and the final pressing temperature is set to 820-880°C; after the last hot forming pressing, the head is air cooled.

[0045] S4: Remove the lining plate 3. Specifically, the lining plate 3 can be removed quickly and easily by lightly grinding the spot welding points. Then, the weld seam of the cladding 2 is welded by surfacing welding to effectively ensure the intergranular corrosion resistance of the weld seam of the cladding 2. Example 2

[0046] The main difference between this embodiment and the first embodiment is that the head is a duplex steel composite plate head (material is S31803, S32205, etc.), the material of the liner 3 is stainless steel, specifically S31603, the thickness of the liner 3 is greater than 20 mm, and the specific welding parameters of the weld of the liner 3 at the cladding 2 are shown in Table 2.

[0047] Table 2 Spot welding parameters of duplex steel composite plate head strip liner

[0048]

[0049] In addition, in this embodiment, the weld seam of the welding base layer 1 is welded by semi-automatic submerged arc welding, which can also improve efficiency. Example 3

[0050] The main difference between this embodiment and the first embodiment is that the head is a 904 composite plate head, the material of the liner 3 is a nickel-based alloy, specifically N06625, the thickness of the liner 3 is greater than 20 mm, and the specific welding parameters of the weld of the liner 3 at the cladding 2 are shown in Table 3.

[0051] Table 3 Spot welding parameters of 904 composite plate head liner

[0052]

[0053] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A head heat treatment forming method, applied to a head having a base layer (1) and a cladding layer (2), wherein the cladding layer (2) is attached to the base layer (1), and the groove on the head is set as a V-shaped inner groove, characterized in that: The following steps are involved: S1: welding the weld of the base layer (1); S2: embedding a lining plate (3) in the weld of the cladding (2) and fixing the lining plate (3) to the cladding (2); the lining plate (3) is in the shape of a long strip, and the length L of the lining plate (3) is set to , the width B of the lining plate (3) is set to , the thickness T of the lining plate (3) is set to , wherein D1 is the diameter of the head before forming, D2 is the shortest distance between the joint of the head and its center, B1 is the single-side peeling width of the coating (2), B2 is the gap of the V-shaped inner groove, and T1 is the thickness of the coating (2); S3: hot forming the head; the head is hot formed at least twice; in the first hot forming, the furnace temperature is not higher than 800°C, the holding temperature is set to 890-950°C, the holding time is set to 40-80 minutes, and the final pressing temperature is set to 820-880°C; in the subsequent hot forming, the holding temperature is set to 890-950°C, the holding time is set to 20-40 minutes, and the final pressing temperature is set to 820-880°C; after the last hot forming, the head is air cooled; S4: removing the lining plate (3) and welding the weld seam of the cladding (2); the weld seam of the cladding (2) is welded by surfacing; the material of the cladding (2) is set to be a nickel-based alloy.

2. A head heat treatment forming method according to claim 1, characterized in that: Before step S2, the dimensions of the coating (2) and the groove on the head are measured, and a lining plate (3) capable of covering the weld of the head is processed.

3. A head heat treatment forming method according to claim 1 or 2, characterized in that: In step S2, the lining plate (3) is fixed to the weld seam of the cladding layer (2) by spot welding, wherein the welding current of the spot welding is set to 70-170A, the welding voltage is set to 10-18V, the welding speed is set to 50-200mm / min, and the interlayer temperature is not higher than 150°C.

4. A head heat treatment forming method according to claim 1 or 2, characterized in that: The material of the base layer (1) is carbon steel.

5. A head heat treatment forming method according to claim 1 or 2, characterized in that: The blunt edge of the V-shaped inner groove is set to 2-3 mm, the gap is set to 0-2 mm, and the angle is set to 53-57°; the single-side peeling width of the coating (2) is set to 4-6 mm; And / or, the method for welding the weld of the base layer (1) is set to submerged arc welding; the welding material is set to a welding wire with a diameter of 4.0 mm, and the material of the welding material is set to F55P3-EF3; the welding current is set to 400-670A, the welding voltage is set to 26-38V, and the welding speed is set to 400-600mm / min.

6. A head heat treatment forming method according to claim 5, characterized in that: The material of the lining plate (3) is set to stainless steel or nickel-based alloy; And / or, the shape of the lining plate (3) matches the shape of the weld seam of the cladding (2).

7. A head heat treatment forming method according to claim 3, characterized in that: In step S4, the spot welding points are polished and the lining plate (3) is removed.

8. The head heat treatment forming method according to claim 1, characterized in that: The head is set as a pressure vessel head.

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