Welding manufacturing method of high-chromium molybdenum steel large hemispherical end socket

Abstract

The invention discloses a welding manufacturing method of a high-chromium molybdenum steel large-scale hemispherical end socket, and relates to the field of welding manufacturing. The invention aims to solve the problems of cost increase and potential quality hazards caused by secondary welding of a high-chromium molybdenum steel weld joint in the existing seal head manufacturing process. The welding manufacturing method comprises the following steps: blanking; assembling and welding a primary splicing welding seam; performing punch forming; assembling and welding a secondary splicing welding seam; and cutting a primary welding seam. The method is used for preparing the large-scale high-chromium molybdenum steel hemispherical end socket.

Description

Technical Field

[0001] The invention relates to the field of welding manufacturing, and in particular to a welding manufacturing method for a large hemispherical head made of high-chromium-molybdenum steel. Background Art

[0002] The head is the core component that seals the end of the pressure vessel and isolates the internal and external media. According to the shape of the head, it can be divided into spherical, elliptical, butterfly, etc. Among them, the spherical head has a cost advantage and is widely used in boilers, petrochemicals, coal chemicals, and heat exchangers and reactors in nuclear power plants. In recent years, the domestic petrochemical, coal chemical and nuclear power industries have developed rapidly, and the expansion of scale has promoted the large-scale and high-parameterization of important devices in the above industries. The overall dimensions and wall thickness of the spherical heads in these devices have increased significantly, and the selected materials have been upgraded from carbon steels such as Q235R and Q345R to chrome-molybdenum steels. The reason is that chrome-molybdenum steel materials such as 12Cr2Mo1V, SA-387Gr22, SA-387Gr91, and G115 have higher chromium and molybdenum element composition, which makes them have better high-temperature strength and corrosion resistance.

[0003] The large-scale dimensions of spherical heads, insufficient equipment capacity of steel plate manufacturers, and transportation conditions limit the width of steel plate materials, resulting in the manufacturing of large high-chromium-molybdenum steel hemispherical heads usually adopting the manufacturing method of welding steel plates in the manufacturer. The increase in head wall thickness and the limitation of forming equipment capacity make high-temperature hot forming above the normalizing temperature inevitable. However, after high-temperature hot forming or heat treatment, the microstructure of the high-chromium-molybdenum steel weld metal changes significantly and the mechanical properties are significantly reduced.

[0004] Therefore, the current solution is to perform secondary welding on the weld metal of the steel plates, that is, to remove the weld metal after the head is hot-formed and re-weld it in the original position. There are many problems in the manufacturing method of this large hemispherical head made of high chromium-molybdenum steel, mainly including: the waste of a large amount of welding materials, energy and working hours leads to a sharp increase in manufacturing costs; the heat input and element diffusion generated by welding have a negative impact on the heat-affected zone of the steel plates on both sides of the weld; and the multiple heat treatments in the weld area make it difficult to control the external dimensions of the head. That is, the difficulty and workload of removing the heat-affected zone of the original weld are extremely large. If the heat-affected zone of the original weld cannot be completely removed, there will be very large quality risks in re-welding. If the original weld and heat-affected zone are removed in large quantities, not only will the workload be large, but it will also make it difficult to ensure the size and shape of the head. These problems significantly increase the manufacturing cost and quality risks of large hemispherical heads made of high chromium-molybdenum steel. It can be seen that a welding and manufacturing method for large hemispherical heads made of high chromium-molybdenum steel is needed to solve the above problems. Summary of the invention

[0005] In order to solve the problems of cost increase and quality risks caused by secondary welding of high chromium-molybdenum steel welds in the existing head manufacturing process, the present invention further proposes a welding manufacturing method for a large hemispherical head made of high chromium-molybdenum steel.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A welding manufacturing method for a large hemispherical head of high chromium-molybdenum steel includes the following steps:

[0008] Step 1: Cut the thick high-chromium-molybdenum steel plate into steel sheets in the longitudinal and transverse directions, and then cut the steel sheets into semicircular steel plates;

[0009] Step 2: welding a single splicing weld: two semicircular steel plates are arranged opposite to each other and spliced ​​into a circular plate, a splicing portion between the two semicircular steel plates is set as a single splicing weld, and welding of the single splicing weld is performed;

[0010] Step 3: stamping: stamping the welded circular plate into a hemispherical head shell;

[0011] Step 4: welding the secondary splicing weld: splice the two hemispherical head shells relative to each other into a spherical head shell, set the splicing point between the two hemispherical head shells as the secondary splicing weld, and weld the secondary splicing weld;

[0012] Step 5: Cut the primary welding seam: Fix the welded spherical head shell and cut at the location of the primary welding seam to cut the spherical head shell into two hemispherical heads.

[0013] Furthermore, during the welding in step 2, the groove of the primary tailored weld is firstly processed at the joint of the two semicircular steel plates, and then the primary tailored weld is welded at the groove of the primary tailored weld.

[0014] Furthermore, after the welding in step 2 is completed, non-destructive testing is performed on the area where the primary joint weld is located, and subsequent steps are performed after the test is qualified.

[0015] Furthermore, the stamping method in step three adopts hot stamping, and after the welded circular plate is heated to a predetermined temperature, a stamping die is used to stamp the circular plate into a hemispherical head shell.

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

[0017] Furthermore, during the welding in step four, the first auxiliary tube is first welded to the middle part of the outer side of the hemispherical head shell, and then the hemispherical head shell is clamped on the vertical lathe using the first auxiliary tube, and the groove of the secondary splicing weld is turned at the joint of the two hemispherical head shells, and then the secondary splicing weld is welded at the groove of the secondary splicing weld.

[0018] Furthermore, during the welding in step four, a group of roller frames are symmetrically arranged on both sides of the welding machine. After the two hemispherical head shells are spliced, the first auxiliary cylinders of the hemispherical head shells are respectively arranged on a group of roller frames and rotated on the roller frames. While rotating, the secondary splicing welds are welded by the welding machine until all the secondary splicing welds are welded.

[0019] Furthermore, after the welding in step four is completed, the spherical head shell is subjected to stress relief heat treatment to eliminate the residual stress generated during the welding of the primary splicing weld and the secondary splicing weld, and reduce the deformation of the hemispherical head shell caused by the heat output during the welding process. Then, non-destructive testing is performed in the area where the secondary splicing weld is located, and subsequent steps are performed after the test is qualified.

[0020] Furthermore, when cutting the primary welding seam in step five, the first auxiliary tube is first removed, and a line is drawn at the position of the primary splicing weld of the spherical head shell. Then, the second auxiliary tube is welded perpendicular to the primary splicing weld, and then the drawn line is cut to separate the spherical head shell into two hemispherical heads.

[0021] Furthermore, after the cutting of the primary welding seam in step 5 is completed, the primary splicing weld seam and its heat affected zone are removed by turning:

[0022] According to the product head design drawing, the allowance line is drawn near the primary joint weld of the hemispherical head, and then the hemispherical head is clamped on the vertical lathe using the second auxiliary cylinder. The heat affected zone of the primary joint weld and the welding grooves between the product head and other parts are removed by turning, thereby completing the manufacture of large hemispherical heads made of high chromium-molybdenum steel.

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

[0024] The purpose of the present invention is to propose a welding manufacturing method for a large hemispherical head made of high chromium-molybdenum steel, which differentially sets the semicircular steel plate splicing welds and the hemispherical head splicing welds used for head stamping, establishes heat treatment processes for these two welds respectively and makes their welding positions non-overlapping, so as to solve the cost increase and quality risks caused by the secondary welding of high chromium-molybdenum steel welds in the manufacturing process of this type of head.

[0025] This method is particularly suitable for the manufacture of high chromium-molybdenum steel hemispherical heads whose dimensions exceed the maximum plate width that the manufacturer can provide. This method avoids the degradation of the organizational structure and the reduction of the mechanical properties of the high chromium-molybdenum steel weld metal after high-temperature hot forming or heat treatment, and can effectively ensure the manufacturing quality of large high chromium-molybdenum steel hemispherical heads.

[0026] The method is used to manufacture a single-joint weld and its heat-affected zone of a high-chromium-molybdenum steel hemispherical head. The weld is removed by cutting and machining during the manufacturing process, thereby eliminating the negative impact of stress generated by multiple heat treatments in the single-joint weld area on the external dimensions of the head and the mechanical properties of the steel plate.

[0027] The butt weld of the large hemispherical head made of high chromium-molybdenum steel manufactured by this method is a secondary butt weld. Since the weld metal has not undergone high-temperature hot forming, there is no need to remove the weld and then re-weld it, and there is no need to select welding materials with higher strength levels to offset the strength reduction caused by high-temperature hot forming, thereby eliminating a large amount of waste in welding materials, energy and working hours. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0030] Figure 3 It is a structural schematic diagram of turning the groove of the secondary splicing weld of the hemispherical head shell in the present invention;

[0031] Figure 4 It is a schematic diagram of the structure when the spherical head shell is welded in the present invention;

[0032] Figure 5 It is a structural schematic diagram of turning and removing a single splicing weld and its heat-affected zone in the present invention. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] Specific implementation method 1: Combination Figures 1 to 5 The present embodiment is described. The welding manufacturing method of a large hemispherical head of high chromium-molybdenum steel described in the present embodiment includes the following process:

[0035] Step 1: Cut the thick high-chromium-molybdenum steel plate into steel plate materials in the longitudinal direction and the transverse direction, and then cut the steel plate materials into semicircular steel plates 1;

[0036] Step 2: welding a single splicing weld: two semicircular steel plates 1 are arranged opposite to each other and spliced ​​into a circular plate, a splicing portion between the two semicircular steel plates 1 is set as a single splicing weld A, and the single splicing weld A is welded;

[0037] Step 3: stamping: stamping the welded circular plate into a hemispherical head shell 2;

[0038] Step 4: welding the secondary splicing weld: the two hemispherical head shells 2 are arranged opposite to each other and spliced ​​into a spherical head shell, the splicing portion between the two hemispherical head shells 2 is set as the secondary splicing weld B, and the secondary splicing weld B is welded;

[0039] Step 5: Cutting the primary welding seam: Fix the welded spherical head shell and cut at the location of the primary welding seam A to cut the spherical head shell 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 CNC cut the two steel plates into semicircular steel plates 1 respectively, and then weld them into the circular plates required for stamping the hemispherical head.

[0041] Due to the large-scale and high-parameterization of important devices in the petrochemical, coal chemical and nuclear power industries, the external dimensions and wall thickness of the spherical heads in these devices are significantly increased, and the steel plate raw materials are all thick rectangular steel plates (usually more than δ80mm thick). Therefore, when cutting, the thick high-chromium-molybdenum steel plates are cut into rectangular steel plates in the longitudinal and transverse directions, and then the steel plates are cut into two semicircular steel plates 1.

[0042] Specific implementation method 2: Combination Figure 1 to Figure 2 To explain this embodiment, during the welding in step 2 of this embodiment, firstly, a groove of a first-piece weld A is processed at the joint of two semicircular steel plates 1, and then a second-piece weld A is welded at the groove of the first-piece weld A.

[0043] The undisclosed technical features in this embodiment are the same as those in the first embodiment.

[0044] The welding grooves of the two semicircular steel plates 1 are processed respectively. The grooves are used for welding the two steel plates to realize the stamping of the hemispherical head. The welding seam between the two is defined as a primary welding seam A.

[0045] Specific implementation method three: Combination Figure 1 to Figure 2 To explain this embodiment, after the welding is completed in step 2 of this embodiment, non-destructive testing is performed on the area where the primary splicing weld A is located, and subsequent steps are performed after the test is qualified.

[0046] The undisclosed technical features in this embodiment are the same as those in the second embodiment.

[0047] Specific implementation method four: Combination Figure 1 to Figure 2 To explain this embodiment, the stamping method in step three of this embodiment adopts hot stamping. After the welded circular plate is heated to a predetermined temperature, the circular plate is stamped into a hemispherical head shell 2 by a stamping die.

[0048] The undisclosed technical features in this embodiment are the same as those in the first embodiment.

[0049] The tailor-welded steel plate is heated to a suitable temperature and is punched into a hemispherical head shell 2 using a die.

[0050] Specific implementation method five: Combination Figure 1 to Figure 2 To illustrate this embodiment, after the hot stamping in step three of this embodiment, a recovery heat treatment is performed to achieve the mechanical properties of the high chromium-molybdenum steel material in the factory state.

[0051] The undisclosed technical features in this embodiment are the same as those in the fourth embodiment.

[0052] Since the steel plate experiences high temperature during the hot stamping process, it is necessary to perform recovery heat treatment to achieve the mechanical properties of the high chromium-molybdenum steel material in its factory state.

[0053] Specific implementation method six: Combination Figures 1 to 4 To illustrate this embodiment, during the welding in step four described in this embodiment, first, a first auxiliary tube 4 is welded to the middle part of the outer side of the hemispherical head shell 2, and then the hemispherical head shell 2 is clamped on the vertical lathe 5 using the first auxiliary tube 4, and the groove of the secondary splicing weld B is turned at the joint of the two hemispherical head shells 2, and then the secondary splicing weld B is welded at the groove of the secondary splicing weld B.

[0054] The undisclosed technical features in this embodiment are the same as those in the first embodiment.

[0055] The first auxiliary cylinder 4 is welded on the formed hemispherical head shell 2 to turn its end, and the groove turned by the vertical lathe 5 is used as the groove of the splicing weld. The splicing weld described 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 groove do not overlap with the position of the primary weld. Differentiate the heat treatment process and position of the semicircular steel plate splicing weld and the hemispherical head splicing weld for head stamping.

[0056] Specific implementation method seven: Combination Figures 1 to 4To illustrate this embodiment, during the welding in step four described in this embodiment, a group of roller frames 7 are symmetrically arranged on both sides of the welding machine 6. After the two hemispherical head shells 2 are spliced, the first auxiliary cylinders 4 of the hemispherical head shells 2 are respectively arranged on a group of roller frames 7 and rotated on the roller frames 7. While rotating, the secondary splicing welds B are welded by the welding machine 6 until all the secondary splicing welds B are welded.

[0057] The undisclosed technical features in this embodiment are the same as those in the sixth embodiment.

[0058] Since most pressure vessel products are two-piece spherical heads or are mass-produced, the two hemispherical head shells 2 are respectively assembled with the first auxiliary cylinder 4, and the two hemispherical head shells 2 are assembled and welded into a complete spherical head shell on a roller frame and a welding operation machine.

[0059] During the welding in step 4, the plane where the secondary splicing weld B is located is perpendicular to the plane where the primary splicing weld A is located. The positions of the two are not overlapped to avoid re-welding at the original position.

[0060] Specific implementation method eight: Combination Figures 1 to 4 To explain this embodiment, after the welding in step four described in this embodiment is completed, the spherical head shell is subjected to stress relief heat treatment to eliminate the residual stress generated during the welding of the primary splicing weld A and the secondary splicing weld B, and reduce the deformation of the hemispherical head shell 2 caused by the heat output during the welding process. Then, non-destructive testing is performed in the area where the secondary splicing weld B is located, and subsequent steps are performed after the test is qualified.

[0061] The undisclosed technical features in this embodiment are the same as those in the first embodiment.

[0062] Specific implementation method nine: Combination Figures 1 to 5 To illustrate this embodiment, when cutting the primary welding seam in step five of this embodiment, first remove the first auxiliary tube 4, and scribe the position of the primary splicing weld A of the spherical head shell. Then, weld the second auxiliary tube 8 perpendicular to the primary splicing weld A, and then cut the scribed position to separate the spherical head shell into two hemispherical heads 3.

[0063] The undisclosed technical features in this embodiment are the same as those in the sixth embodiment.

[0064] Specific implementation method ten: Combination Figures 1 to 5 To illustrate this embodiment, after the first welding seam is cut in step 5 of this embodiment, the first splicing weld A and its heat affected zone are removed by turning:

[0065] According to the product head design drawing, an allowance line is drawn near the primary splicing weld A of the hemispherical head 3, and then the hemispherical head 3 is clamped on the vertical lathe 5 using the second auxiliary cylinder 8. The heat-affected zone of the primary splicing weld A and the welding grooves between the product head and other parts are removed by turning, thereby completing the manufacture of a large hemispherical head made of high chromium-molybdenum steel.

[0066] The undisclosed technical features in this embodiment are the same as those in the ninth embodiment.

[0067] The primary splicing weld that had undergone high-temperature hot forming and its heat-affected zone were removed, and the secondary splicing weld that had not undergone high-temperature hot forming was used to achieve the final splicing of the hemispherical head.

[0068] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A welding manufacturing method for a large hemispherical head of high chromium-molybdenum steel, characterized in that: The method comprises the following steps: Step 1, cutting: cutting the thick high-chromium-molybdenum steel plate into steel plate materials in the longitudinal direction and the transverse direction, and then cutting the steel plate materials into semicircular steel plates (1); Step 2: welding a primary splicing weld: two semicircular steel plates (1) are arranged opposite to each other to form a circular plate, a splicing portion between the two semicircular steel plates (1) is set as a primary splicing weld (A), and the primary splicing weld (A) is welded; Step 3: stamping: stamping the welded circular plate into a hemispherical head shell (2); Step 4: welding the secondary splicing weld: the two hemispherical head shells (2) are arranged opposite to each other and spliced ​​into a spherical head shell, the splicing portion between the two hemispherical head shells (2) is set as the secondary splicing weld (B), and the secondary splicing weld (B) is welded; Step 5: Cutting the primary welding seam: Fix the welded spherical head shell and cut at the location of the primary welding seam (A) to cut the spherical head shell into two hemispherical heads (3).

2. The welding manufacturing method of a large hemispherical head made of high chromium-molybdenum steel according to claim 1 is characterized in that: During the welding in step 2, the groove of the primary tailored weld (A) is firstly processed at the joint of the two semicircular steel plates (1), and then the primary tailored weld (A) is welded at the groove of the primary tailored weld (A).

3. The welding manufacturing method of a large hemispherical head made of high chromium-molybdenum steel according to claim 2 is characterized in that: After the welding in step 2 is completed, non-destructive testing is performed on the area where the primary weld (A) is located, and subsequent steps are performed after the test is qualified.

4. The welding manufacturing method of a large hemispherical head made of high chromium-molybdenum steel according to claim 1 is characterized in that: The stamping method in step three adopts hot stamping, and after the welded circular plate is heated to a predetermined temperature, a stamping die is used to stamp the circular plate into a hemispherical head shell (2).

5. The welding manufacturing method of a large hemispherical head made of high chromium-molybdenum steel according to claim 4 is characterized in that: After the hot stamping in step three, a recovery heat treatment is performed to achieve the mechanical properties of the high chromium-molybdenum steel material in the factory state.

6. The welding manufacturing method of a large hemispherical head made of high chromium-molybdenum steel according to claim 1 is characterized in that: During the welding in step 4, a first auxiliary cylinder (4) is first welded to the middle of the outer side of the hemispherical head shell (2), and then the hemispherical head shell (2) is clamped on the vertical lathe (5) using the first auxiliary cylinder (4), and a groove of a secondary joint weld (B) is machined at the joint of the two hemispherical head shells (2), and then the secondary joint weld (B) is welded at the groove of the secondary joint weld (B).

7. The welding manufacturing method of a large hemispherical head made of high chromium-molybdenum steel according to claim 6 is characterized in that: During the welding in step 4, a group of roller frames (7) are symmetrically arranged on both sides of the welding machine (6). After the two hemispherical head shells (2) are spliced, the first auxiliary cylinders (4) of the hemispherical head shells (2) are respectively arranged on a group of roller frames (7) and rotated on the roller frames (7). While rotating, the secondary splicing welds (B) are welded by the welding machine (6) until the secondary splicing welds (B) are completely welded.

8. The welding manufacturing method of a large hemispherical head made of high chromium-molybdenum steel according to claim 1 is characterized in that: After the welding in step 4 is completed, the spherical head shell is subjected to stress relief heat treatment to eliminate the residual stress generated during the welding of the primary splicing weld (A) and the secondary splicing weld (B), reduce the deformation of the hemispherical head shell (2) caused by the heat output during the welding process, and then non-destructive testing is performed in the area where the secondary splicing weld (B) is located. After passing the test, the subsequent steps are carried out.

9. The welding manufacturing method of a large hemispherical head made of high chromium-molybdenum steel according to claim 6 is characterized in that: When cutting the primary welding seam in step 5, the first auxiliary tube (4) is first removed, and a line is drawn at the position of the primary joint weld (A) of the spherical head shell. Then, the second auxiliary tube (8) is welded perpendicular to the primary joint weld (A), and then the line is cut to separate the spherical head shell into two hemispherical heads (3).

10. The welding manufacturing method of a large hemispherical head made of high chromium-molybdenum steel according to claim 9 is characterized in that: After the cutting of the primary welding seam in step 5 is completed, the primary welding seam (A) and its heat affected zone are removed by turning: According to the product head design drawing, an allowance line is drawn near the primary joint weld (A) of the hemispherical head (3), and then the hemispherical head (3) is clamped on the vertical lathe (5) using a second auxiliary cylinder (8), and the heat-affected zone of the primary joint weld (A) and the welding grooves between the product head and other parts are removed by turning, thereby completing the manufacture of a large hemispherical head made of high chromium-molybdenum steel.

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