A welding manufacturing method of a large high-chromium molybdenum steel semi-spherical head

Abstract

The application discloses a welding manufacturing method of a large high-chromium-molybdenum steel semi-spherical head and relates to the field of welding manufacturing. The application is used for solving the problems of cost increase and quality hidden danger caused by secondary welding of a high-chromium-molybdenum steel welding seam in the manufacturing process of the existing head. The welding manufacturing method comprises the following processes: blanking, assembling and welding a first splicing welding seam, stamping forming, assembling and welding a second splicing welding seam and cutting the first welding seam. The application is used for the preparation of the large high-chromium-molybdenum steel semi-spherical head.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding manufacturing, in particular to a welding manufacturing method of a large high-chrome-molybdenum steel semi-spherical head. BACKGROUND

[0002] The head is a core component for closing the end of a pressure vessel and isolating the internal and external media. According to the shape of the head, it can be divided into spherical, elliptical, butterfly-shaped, etc. Among them, the spherical head has cost advantages and is widely used in boilers, petrochemical industry, coal chemical industry, nuclear power devices, heat exchangers and reactor devices. In recent years, the domestic petrochemical industry, coal chemical industry and nuclear power industry have developed rapidly, and the expansion of scale has promoted the large-scale and high-parameterization of important devices in the above-mentioned industries. The spherical head in these devices has significantly increased in size and wall thickness, and the selected material has been upgraded from carbon steel such as Q235R and Q345R to chrome-molybdenum steel. The reason is that chrome-molybdenum steel materials such as 12Cr2Mo1V, SA-387Gr22, SA-387Gr91 and G115 have higher chromium and molybdenum elements, which make them have more excellent high-temperature strength and corrosion resistance.

[0003] The large size of the spherical head and the insufficient equipment capacity of the steel plate manufacturer and the transportation conditions limit the width of the steel plate material, which makes the manufacturing of the large high-chrome-molybdenum steel semi-spherical head usually adopt the manufacturing method of forming after splicing and welding of the steel plate in the manufacturing plant. The increase of the head wall thickness and the limitation of the forming equipment capacity make it impossible to avoid high-temperature hot forming above the normalizing temperature. However, the microstructure of the high-chrome-molybdenum steel weld metal changes significantly after high-temperature hot forming or heat treatment, and the mechanical properties decrease significantly.

[0004] Therefore, the current solution is to re-weld the weld metal of the spliced steel plate, that is, to remove and re-weld the weld metal at the original position after the head is hot formed. This manufacturing method of large high-chrome-molybdenum steel semi-spherical head has many problems, mainly including: a large amount of waste of welding materials, energy and working hours, which greatly increases the manufacturing cost; the heat input and element diffusion generated by welding have a negative impact on the heat-affected zone of the steel plate on both sides of the weld; multiple heat treatments in the weld area make it difficult to control the size of the head. That is, the difficulty and workload of removing the original weld heat-affected zone is extremely large, and if the original weld heat-affected zone cannot be completely removed, there is a very large quality risk in re-welding. If a large amount of original weld and heat-affected zone is removed, not only the workload is large, but also it is easy to make it difficult to guarantee the size and shape of the head. These problems significantly increase the manufacturing cost and quality risk of the large high-chrome-molybdenum steel semi-spherical head. Therefore, a welding and manufacturing method of large high-chrome-molybdenum steel semi-spherical head is needed to solve the above problems. SUMMARY

[0005] The application aims to solve the problems of cost increase and quality hidden trouble caused by secondary welding of high chromium molybdenum steel weld in the existing head manufacturing process, and further proposes a welding manufacturing method of large-scale high chromium molybdenum steel semi-spherical head.

[0006] The technical scheme adopted by the application to solve the above technical problems is:

[0007] A welding manufacturing method of large-scale high chromium molybdenum steel semi-spherical head comprises the following processes:

[0008] Step one, cut the high chromium molybdenum steel plate of large thickness into steel plate materials in the longitudinal and transverse directions, and then cut the steel plate materials into semicircular steel plates;

[0009] Step two, assemble and weld the primary splice weld: set two semicircular steel plates opposite to splice into a circular plate, set the splice between the two semicircular steel plates as a primary splice weld, and weld the primary splice weld;

[0010] Step three, stamping forming: stamp the welded circular plate into a semi-spherical head shell;

[0011] Step four, assemble and weld the secondary splice weld: set two semi-spherical head shells opposite to splice into a spherical head shell, set the splice between the two semi-spherical head shells as a secondary splice weld, and weld the secondary splice weld;

[0012] Step five, cut the primary welding weld: fix the welded spherical head shell, and cut at the position of the primary splice weld to cut the spherical head shell into two semi-spherical heads.

[0013] Further, in the step two, first, the groove of the primary splice weld is processed at the splice of the two semicircular steel plates, and then the primary splice weld is welded at the groove of the primary splice weld.

[0014] Further, after the assembly and welding in the step two, non-destructive testing is performed on the region where the primary splice weld is located, and the subsequent steps are performed after the testing is qualified.

[0015] Further, the stamping mode in the step three is hot stamping, the welded circular plate is heated to a certain temperature, and then the circular plate is stamped into a semi-spherical head shell by using a stamping die.

[0016] Further, after the hot stamping in the step three, performance recovery heat treatment is performed to achieve the mechanical properties of the high chromium molybdenum steel material in the factory state.

[0017] Further, in the step four, when welding, first weld the first auxiliary cylinder on the middle part of the outside of the hemispherical head shell, then clamp the hemispherical head shell on the vertical lathe by the first auxiliary cylinder, turn the groove of the second joint welding seam on the joint of the two hemispherical head shells, and then weld the second joint welding seam on the groove.

[0018] Further, in the step four, when welding, a set of roller frames are symmetrically arranged on both sides of the welding machine, after the two hemispherical head shells are jointed, the first auxiliary cylinder of the hemispherical head shell is arranged on a set of roller frames and rotated on the roller frame, and the second joint welding seam is welded by the welding machine during the rotation, until the second joint welding seam is completely welded.

[0019] Further, after the welding in the step four is completed, the spherical head shell is subjected to stress relief heat treatment to eliminate the residual stress generated in the welding process of the first joint welding seam and the second joint welding seam, reduce the deformation of the hemispherical head shell caused by the heat output in the welding process, and then perform nondestructive testing on the area of the second joint welding seam, and after the testing is qualified, the subsequent steps are performed.

[0020] Further, in the step five, when cutting the first welding seam, first remove the first auxiliary cylinder, and then mark the position of the first joint welding seam of the spherical head shell, then weld the second auxiliary cylinder perpendicular to the first joint welding seam, and then cut the marked position to separate the spherical head shell into two hemispherical heads.

[0021] Further, after the cutting of the first welding seam in the step five is completed, the first joint welding seam and the heat affected zone are removed by turning.

[0022] According to the head design drawing of the product, a margin line is marked near the first joint welding seam of the hemispherical head, then the hemispherical head is clamped on the vertical lathe by the second auxiliary cylinder, and the heat affected zone of the first joint welding seam and the welding groove of the product head and other parts are removed by turning, so that the manufacturing of the large hemispherical head of high chromium molybdenum steel is completed.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The purpose of the present application is to provide a welding manufacturing method for a large hemispherical head of high chromium molybdenum steel, which differentiates the joint welding seam of the semicircular steel plate for head stamping and the joint welding seam of the hemispherical head, respectively establishes the heat treatment process of the two kinds of welding seams, and makes the welding positions of the two kinds of welding seams not coincide, so as to solve the cost increase and quality hidden trouble caused by the second welding of the high chromium molybdenum steel welding seam in the manufacturing process of the head.

[0025] The method is particularly suitable for manufacturing high-chromium-molybdenum steel hemispherical heads with a size exceeding the maximum plate width that can be provided by a manufacturer. The method avoids the deterioration of the microstructure and the reduction of the mechanical properties of the high-chromium-molybdenum steel weld metal after being subjected to high-temperature hot forming or heat treatment, and can effectively guarantee the manufacturing quality of the high-chromium-molybdenum steel large hemispherical head.

[0026] The primary splicing weld and the heat-affected zone thereof of the high-chromium-molybdenum steel hemispherical head manufactured by the method are removed by cutting and machining during the manufacturing process, thereby eliminating the negative effects of the stress generated by multiple heat treatments in the primary splicing weld area on the outer dimensions of the head and the mechanical properties of the steel plate.

[0027] The splicing weld of the high-chromium-molybdenum steel large hemispherical head manufactured by the method is a secondary splicing weld. Since the weld metal does not undergo high-temperature hot forming, it is not necessary to re-weld the weld after removal or to select a higher strength grade of welding material to offset the strength reduction caused by high-temperature hot forming, thereby eliminating the waste of a large amount of welding material, energy, and working hours. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a structural schematic diagram of the steel plate material blanking in the welding manufacturing process of the present application;

[0029] Figure 2 is a structural schematic diagram of the hemispherical head shell formed by stamping in the present application;

[0030] Figure 3 is a structural schematic diagram of the hemispherical head shell when the groove of the secondary splicing weld is turned in the present application;

[0031] Figure 4 is a structural schematic diagram of the hemispherical head shell when the spherical head is welded in the present application;

[0032] Figure 5 is a structural schematic diagram of the hemispherical head shell when the primary splicing weld and the heat-affected zone thereof are removed by turning in the present application. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0034] Specific embodiment one: in combination with Figures 1 to 5 To illustrate the present embodiment, the welding manufacturing method of the high-chromium-molybdenum steel large hemispherical head according to the present embodiment includes the following processes:

[0035] Step one, cut the high-chromium-molybdenum steel plate with a large thickness into steel plate materials in the longitudinal and transverse directions, and then cut the steel plate materials into semicircular steel plates 1;

[0036] Step two, welding once splicing weld: two half-round steel plates 1 are arranged opposite to splice into a circular plate, the splicing between the two half-round steel plates 1 is set as a once splicing weld A, and the welding of the once splicing weld A is carried out.

[0037] Step three, stamping forming: the welded circular plate is stamped into a hemispherical head shell 2.

[0038] Step four, welding twice splicing weld: two hemispherical head shells 2 are arranged opposite to splice into a spherical head shell, the splicing between the two hemispherical head shells 2 is set as a twice splicing weld B, and the welding of the twice splicing weld B is carried out.

[0039] Step five, cutting once welding weld: the welded spherical head shell is fixed, and cutting is carried out at the location of the once splicing weld A, so that the spherical head shell is cut into two hemispherical heads 3.

[0040] Since the unfolded size of the hemispherical head exceeds the maximum plate width that the manufacturer can provide, the technical solution adopted is to cut two steel plates into half-round steel plates 1 respectively by numerical control, and then weld them into a circular plate required for stamping forming of the hemispherical head.

[0041] Due to the large-scale and high-parameterization of important devices in the petroleum chemical industry, coal chemical industry and nuclear power industry, the size and wall thickness of the spherical head in these devices have increased significantly, and the raw material of the steel plate is a large thickness rectangular steel plate (usually more than δ80mm thick), so when cutting, the large thickness high chromium molybdenum steel plate is cut into a rectangular steel plate in the longitudinal and transverse directions, and then the steel plate is cut into two half-round steel plates 1.

[0042] Specific implementation method two: combined with Figures 1 to 2 It is explained that in the step two welding of the embodiment, first, a bevel for the once splicing weld A is processed at the splicing of the two half-round steel plates 1, and then the welding of the once splicing weld A is carried out at the bevel of the once splicing weld A.

[0043] The technical features not disclosed in the embodiment are the same as those in the specific implementation method one.

[0044] The splicing bevels of the two half-round steel plates 1 are processed respectively, and the bevels are used for splicing the two steel plates to realize stamping of the hemispherical head, and the splicing welds of the two are defined as the once splicing weld A.

[0045] Specific implementation method three: combined with Figures 1 to 2 It is explained that in the step two welding of the embodiment, after the welding is completed, non-destructive testing is carried out in the area where the once splicing weld A is located, and after the testing is qualified, the subsequent steps are carried out.

[0046] The technical features not disclosed in this embodiment are the same as those in Embodiment Two.

[0047] Embodiment Four: Combination Figures 1 to 2 In this embodiment, the stamping method in Step Three is hot stamping. The welded circular plate is heated to a certain temperature, and then the circular plate is stamped into a hemispherical head shell 2 by using a stamping die.

[0048] The technical features not disclosed in this embodiment are the same as those in Embodiment One.

[0049] The tailor-welded steel plate is heated to an appropriate temperature, and then it is stamped into a hemispherical head shell 2 by using a die.

[0050] Embodiment Five: Combination Figures 1 to 2 In this embodiment, after hot stamping in Step Three, a performance recovery heat treatment is performed to achieve the mechanical properties of the high-chromium molybdenum steel material in the factory state.

[0051] The technical features not disclosed in this embodiment are the same as those in Embodiment Four.

[0052] Since the steel plate undergoes high temperature during hot stamping, a performance recovery heat treatment is needed to achieve the mechanical properties of the high-chromium molybdenum steel material in the factory state.

[0053] Embodiment Six: Combination Figures 1 to 4 In this embodiment, during the welding in Step Four, first, a first auxiliary cylinder 4 is welded on the middle part of the outside of the hemispherical head shell 2, then the hemispherical head shell 2 is clamped on the vertical lathe 5 by using the first auxiliary cylinder 4, the bevel of the secondary splicing weld B is turned out at the splicing part of the two hemispherical head shells 2, and then the welding of the secondary splicing weld B is performed at the bevel of the secondary splicing weld B.

[0054] The technical features not disclosed in this embodiment are the same as those in Embodiment One.

[0055] The first auxiliary cylinder 4 is welded on the already formed hemispherical head shell 2, and the end part is turned. The bevel of the vertical lathe 5 is used as the splicing weld bevel. The splicing weld in this step is the second splicing of the hemispherical head shell 2, so it is defined as the secondary splicing weld B. The secondary splicing weld B and the bevel do not coincide with the position of the primary weld. The heat treatment process and position of the splicing weld of the semicircular steel plate for head stamping and the splicing weld of the hemispherical head are differentiated.

[0056] Embodiment Seven: Combination Figures 1 to 4In the step four, a set of roller racks 7 are symmetrically arranged on both sides of the welding machine 6, and the two hemispherical head shells 2 are spliced, and then the first auxiliary cylinder 4 of the hemispherical head shell 2 is arranged on the roller rack 7 and rotated on the roller rack 7, and the secondary splicing weld B is welded by the welding machine 6 at the same time, until the secondary splicing weld B is completely welded.

[0057] The technical features not disclosed in the embodiment are the same as those in the sixth embodiment.

[0058] Since the pressure vessel products are mostly two-piece spherical heads or batch production, the two hemispherical head shells 2 are assembled with the first auxiliary cylinder 4 respectively, and the two hemispherical head shells 2 are assembled and welded into a complete spherical head shell on the roller rack and the welding manipulator.

[0059] The plane where the secondary splicing weld B is located in the step four is perpendicular to the plane where the primary splicing weld A is located. The positions of the two are not coincident, which avoids re-welding in the original position.

[0060] Embodiment eight: combination Figures 1 to 4 In the step four, the spherical head shell is subjected to stress relief heat treatment after the welding is completed, the residual stress generated in the welding process of the primary splicing weld A and the secondary splicing weld B is eliminated, the deformation of the hemispherical head shell 2 caused by heat output in the welding process is reduced, and then nondestructive testing is performed on the region where the secondary splicing weld B is located. After the testing is qualified, subsequent steps are performed.

[0061] The technical features not disclosed in the embodiment are the same as those in the first embodiment.

[0062] Embodiment nine: combination Figures 1 to 5 In the step five, the first auxiliary cylinder 4 is removed first, and a line is drawn at the position of the primary splicing weld A of the spherical head shell, then the second auxiliary cylinder 8 is welded perpendicular to the primary splicing weld A, and the line is cut to separate the spherical head shell into two hemispherical heads 3.

[0063] The technical features not disclosed in the embodiment are the same as those in the sixth embodiment.

[0064] Embodiment ten: combination Figures 1 to 5 In the step five, after the cutting of the primary splicing weld A is completed, the primary splicing weld A and the heat affected zone thereof are removed by turning.

[0065] According to the head design drawing of the product, a margin line is drawn near the first splice weld A of the hemispherical head 3, then the hemispherical head 3 is clamped on the vertical lathe 5 by using the second auxiliary cylinder 8, and the heat affected zone of the first splice weld A and the welding bevel of the head and other parts are removed by turning, thereby completing the manufacturing of the large hemispherical head of high-chrome-molybdenum steel.

[0066] The technical features not disclosed in the embodiment are the same as those in Embodiment Nine.

[0067] The first splice weld and the heat affected zone thereof which have experienced high-temperature hot forming are removed, and the second splice weld which has not experienced high-temperature hot forming is used to realize the splicing of the final hemispherical head.

[0068] The basic principles and main features of the present application and the advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A welding manufacturing method of a large-scale semi-spherical head of high-chromium molybdenum steel, characterized in that: The method comprises the following steps: Step one, blanking: cutting the large-thickness high-chrome molybdenum steel plate into a steel plate material in the longitudinal direction and the transverse direction, and then cutting the steel plate material into a semicircular steel plate (1); Step two, welding and assembling a first assembly weld: oppositely arranging two semicircular steel plates (1) to assemble a circular plate material, arranging the assembly position between the two semicircular steel plates (1) as a first assembly weld (A), and welding the first assembly weld (A); Step three, stamping and forming: stamping the welded circular plate material into a hemispherical head shell (2); Step four, welding and assembling a second assembly weld: oppositely arranging two hemispherical head shells (2) to assemble a spherical head shell, arranging the assembly position between the two hemispherical head shells (2) as a second assembly weld (B), and welding the second assembly weld (B); Step five, cutting a first welding weld: fixing the welded spherical head shell, and cutting at the position of the first assembly weld (A) to cut the spherical head shell into two hemispherical heads (3); In the welding of step four, first, a first auxiliary cylinder (4) is welded at the middle of the outer side of the hemispherical head shell (2), then the hemispherical head shell (2) is clamped on a vertical lathe (5) by using the first auxiliary cylinder (4), a bevel of the second assembly weld (B) is turned at the assembly position of the two hemispherical head shells (2), and then the welding of the second assembly weld (B) is performed at the bevel of the second assembly weld (B); In the cutting of the first welding weld in step five, first, the first auxiliary cylinder (4) is removed, and a line is drawn at the position of the first assembly weld (A) of the spherical head shell, then a second auxiliary cylinder (8) is welded perpendicular to the first assembly weld (A), and the line is cut to separate the spherical head shell into two hemispherical heads (3); After the cutting of the first welding weld in step five is completed, the first assembly weld (A) and the heat-affected zone thereof are removed by turning; According to the head design drawing of the product, a margin line is drawn near the first assembly weld (A) of the hemispherical head (3), then the hemispherical head (3) is clamped on the vertical lathe (5) by using the second auxiliary cylinder (8), and the heat-affected zone of the first assembly weld (A) and the welding bevel of the product head and other components are removed by turning, so that the manufacturing of the large high-chrome molybdenum steel hemispherical head is completed.

2. The welding manufacturing method of a large hemispherical head made of high-chromium molybdenum steel according to claim 1, characterized in that: In the welding of step two, first, a bevel of the first assembly weld (A) is processed at the assembly position of the two semicircular steel plates (1), and then the welding of the first assembly weld (A) is performed at the bevel of the first assembly weld (A).

3. The welding manufacturing method of a large hemispherical head made of high-chromium molybdenum steel according to claim 2, characterized in that: After the welding of step two is completed, nondestructive testing is performed at the position of the first assembly weld (A), and then the subsequent steps are performed after the testing is qualified.

4. The method of claim 1, wherein the method further comprises: In step three, the stamping is hot stamping, the welded circular plate material is heated to a predetermined temperature, and then the circular plate material is stamped into a hemispherical head shell (2) by using a stamping die. ​ 5. The welding manufacturing method of a large hemispherical head made of high-chromium molybdenum steel according to claim 4, characterized in that: After the hot stamping in step three, performance recovery heat treatment is performed to achieve the mechanical properties of the high-chrome molybdenum steel material in the factory state.

6. The method of claim 1, wherein the method further comprises: In the fourth step, a set of roller frames (7) are symmetrically arranged on both sides of the welding machine (6) during the welding process. After the two hemispherical head shells (2) are spliced, the first auxiliary cylinder (4) of the hemispherical head shell (2) is arranged on a set of roller frames (7) and rotated on the roller frames (7). At the same time, the secondary splicing weld (B) is welded by the welding machine (6) until the secondary splicing weld (B) is completely welded. ​ 7. The welding manufacturing method of a large hemispherical head made of high-chromium molybdenum steel according to claim 1, characterized in that: After the welding in the fourth step is completed, the spherical head shell is subjected to stress relief heat treatment to eliminate the residual stress generated during the welding process of the primary splicing weld (A) and the secondary splicing weld (B), reduce the deformation of the hemispherical head shell (2) caused by heat output during the welding process, and then perform non-destructive testing on the area where the secondary splicing weld (B) is located. After passing the detection, the subsequent steps are carried out.

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