JP5940311B2 - Joining method and joining structure - Google Patents

Description

  The present invention relates to a joining method for welding a dissimilar metal to a base material of a low alloy steel, and a joining structure joined by the joining method.

  Conventionally, for example, as described in Patent Document 1, in pre-welding of low alloy steel (2.25Cr-1Mo steel), it is generally performed to increase the preheating temperature. Increasing the preheating temperature is effective in reducing the residual stress generated in the weld and increasing the ductility.

JP-A-10-204544

  By the way, for example, when manufacturing the steam generator applied to a nuclear facility, in order to maintain the roundness of a cylindrical trunk | drum, the reinforcement metal object is temporarily installed in the internal peripheral surface of the said trunk | drum. Low-alloy steel is used for the body, and relatively inexpensive carbon steel is used for the reinforcement hardware. As described above, in the welding of the low alloy steel, it is necessary to preheat, and when the reinforcing hardware is welded to the body, the body and the reinforcing hardware are preheated (for example, 150 ° C.). . Thus, the work of preheating the body part and the reinforcing hardware in the space surrounded by the body part is poor in work environment and workability, and the burden on the operator is large. Therefore, it is desired to improve workability.

  This invention solves the subject mentioned above, and it aims at providing the joining method and joining structure which can improve the workability | operativity which welds the joining metal of a dissimilar metal to low alloy steel.

In order to achieve the above-described object, the joining method of the present invention is a joining method of welding a dissimilar metal joint metal made of different materials to a base material of low alloy steel. For the build-up welding of the alloy steel, and then for the build-up welding of the dissimilar metal on the build-up welding surface of the low alloy steel, and then for the build-up welding of the dissimilar metal It is seen containing a step of welding the joint hardware by dissimilar metal filler, and in the step of welding the bonding hardware, dissimilar metal by filler of the dissimilar metals with respect to overlay welding of the dissimilar metal The positioning member is welded and joined to the positioning member with a filler metal of a dissimilar metal .

  According to this joining method, preheating is performed in the process of overlay welding of low alloy steel on the joint surface on the base metal side and the process of overlay welding of dissimilar metal on the overlay weld surface of low alloy steel. Although it is necessary, preheating is not required in the process of welding and joining the joint metal to the overlay welding of the dissimilar metal. As a result, since the joining hardware itself is not preheated, the workability of welding the joining material of the dissimilar metal to the low alloy steel can be improved.

  According to this joining method, preheating is not required when the positioning member is welded and joined to the overlay welding of the dissimilar metal, and when the joining hardware is welded and joined to the positioning member. As a result, since the positioning member and the joint metal are not preheated, the workability of welding and joining the dissimilar metal joint metal to the low alloy steel can be improved. In addition, the bonding position of the bonding hardware can be determined by the positioning member. Furthermore, when removing the joining hardware from the base material, the joining hardware can be easily detached from the base material by deleting the filler material portion that is the welding location of the positioning member for the overlay welding of the dissimilar metal.

In order to achieve the above-described object, the joining structure of the present invention includes a base material of low alloy steel , a low alloy steel layer joined to the joining surface on the base material side, and a dissimilar material having a material different from that of the low alloy steel. a dissimilar metal layer bonded onto said low alloy steel layer made of a metal, a positioning member of the dissimilar metal joined by filler of the dissimilar metal to the different metal layer, the dissimilar metal with respect to the positioning member And a dissimilar metal joint hardware joined to the base material via the positioning member, the dissimilar metal layer, and the low alloy steel layer .

  According to this joining structure, preheating is necessary for overlay welding of a low alloy steel layer to the joint surface on the base metal side and overlay welding of a dissimilar metal layer to the low alloy steel layer. No preheating is required for the welded joint of the metal fitting to the joint. As a result, since the joining hardware itself is not preheated, the workability of welding the joining material of the dissimilar metal to the low alloy steel can be improved.

  According to this joining structure, preheating is not required for welding joining of the positioning member to the dissimilar metal layer and welding joining of the joint metal to the positioning member. As a result, since the positioning member and the joint metal are not preheated, the workability of welding and joining the dissimilar metal joint metal to the low alloy steel can be improved. In addition, the bonding position of the bonding hardware can be determined by the positioning member. Furthermore, when removing the joining hardware from the base material, the joining hardware can be easily detached from the base material by deleting the filler material portion that is the welded portion of the positioning member to the dissimilar metal layer.

  ADVANTAGE OF THE INVENTION According to this invention, the workability | operativity which weld-joins the metal joint of dissimilar metal to low alloy steel can be improved.

FIG. 1 is a cross-sectional view of a joint structure according to an embodiment of the present invention. FIG. 2 is a front view of the joint structure according to the embodiment of the present invention. FIG. 3 is a cross-sectional view of another joint structure according to the embodiment of the present invention. FIG. 4 is a process diagram of the bonding method according to the embodiment of the present invention. FIG. 5 is a process diagram of the bonding method according to the embodiment of the present invention. FIG. 6 is a process diagram of the bonding method according to the embodiment of the present invention. FIG. 7 is an explanatory diagram showing a configuration of a steam generator to which the joining structure according to the embodiment of the present invention is applied. FIG. 8 is a side view at the time of manufacturing the steam generator to which the joining structure according to the embodiment of the present invention is applied. FIG. 9 is a front view at the time of manufacture of the steam generator to which the joining structure according to the embodiment of the present invention is applied.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  FIG. 7 is an explanatory diagram showing a configuration of a steam generator to which the joining structure according to the present embodiment is applied. The steam generator 101 is used, for example, in a pressurized water reactor (PWR: Pressurized Water Reactor). The pressurized water reactor uses light water as a reactor coolant and neutron moderator. The pressurized water reactor sends primary cooling water to the steam generator 101 as high-temperature high-pressure water that does not boil light water over the entire core. In the steam generator 101, the heat of the high-temperature and high-pressure primary cooling water is transmitted to the secondary cooling water, and water vapor is generated in the secondary cooling water. Then, the steam generator is rotated by this steam to generate electricity.

  The steam generator 101 has a trunk portion 102. The trunk portion 102 has a hollow cylindrical shape that extends in the vertical direction and is hermetically sealed. The lower half portion has a slightly smaller diameter than the upper half portion. The trunk portion 102 is provided with a tube group outer cylinder 103 having a cylindrical shape disposed at a predetermined distance from the inner wall surface of the trunk portion 102 in the lower half portion thereof. The lower end portion of the tube group outer tube 103 extends to the vicinity of the tube plate 104 disposed below in the lower half of the body portion 102. A heat transfer tube group 105 </ b> A is provided in the tube group outer tube 103. The heat transfer tube group 105A includes a plurality of heat transfer tubes 105 having an inverted U shape. In the heat transfer tube group 105A, the above-described inverted U-shaped arc portion of the heat transfer tube 105 is arranged at the upper end portion thereof. The heat transfer tube 105 constitutes a heat transfer tube layer in which the arc portions having large diameters are arranged from the center toward the outside, and the upper end portion of the heat transfer tube group 105A is changed by changing the diameter while overlapping the heat transfer tube layers. It has a hemispherical shape. The hemispherical portion of the heat transfer tube group 105A is a bracing member for suppressing fluid excitation vibration that may occur when the primary cooling water passes through the heat transfer tubes 105 between the arc portions of the heat transfer tube layers. 105a is provided. Each heat transfer tube 105 has a U-shaped arc portion facing upward, a lower end portion is inserted and supported in the tube hole 104a of the tube plate 104, and an intermediate portion is connected to the tube via a plurality of tube support plates 106. It is supported by the group outer cylinder 103. The tube support plate 106 is formed with a large number of tube holes 106a, and the heat transfer tubes 105 are inserted into the tube holes 106a to support the heat transfer tubes 105.

  The body 102 is provided with a water chamber 107 at its lower end. The water chamber 107 is divided into an entrance chamber 107A and an exit chamber 107B by a partition wall 108. One end of each heat transfer tube 105 communicates with the entrance chamber 107A, and the other end of each heat transfer tube 105 communicates with the exit chamber 107B. The entrance chamber 107A is formed with an inlet nozzle 107Aa that communicates with the outside of the body portion 102, and the exit chamber 107B is formed with an exit nozzle 107Ba that communicates with the outside of the body portion 102. The inlet nozzle 107Aa is connected to a cooling water pipe (not shown) through which primary cooling water is sent from the pressurized water reactor, and the outlet nozzle 107Ba sends the primary cooling water after heat exchange to the pressurized water reactor. The cooling water piping (not shown) to send is connected.

  In the upper half of the body portion 102, a steam separator 109 that separates the feed water into steam and hot water, and a moisture separator that removes the moisture from the separated steam and makes it close to dry steam. 110 is provided. Between the steam separator 109 and the heat transfer tube group 105A, a water supply pipe 111 for supplying secondary cooling water from the outside into the body portion 102 is inserted. Further, the body 102 has a steam discharge port 112 formed at the upper end thereof. In addition, the body portion 102 has a pipe plate in which the secondary cooling water supplied from the water supply pipe 111 into the body portion 102 flows between the body portion 102 and the tube group outer cylinder 103 in the lower half portion thereof. A water supply passage 113 is formed that is folded back at 104 and raised along the heat transfer tube group 105A. The steam outlet 112 is connected to a cooling water pipe (not shown) for sending steam to the turbine, and the water supply pipe 111 is a two-way steam that has been cooled by a condenser (not shown). A cooling water pipe (not shown) for supplying the next cooling water is connected.

  In such a steam generator 101, the primary cooling water heated in the pressurized water reactor is sent to the entrance chamber 107A, circulates through the numerous heat transfer tubes 105, and reaches the exit chamber 107B. On the other hand, the secondary cooling water cooled by the condenser is sent to the water supply pipe 111 and rises along the heat transfer pipe group 105 </ b> A through the water supply path 113 in the trunk portion 102. At this time, heat exchange is performed between the high-pressure and high-temperature primary cooling water and the secondary cooling water in the body portion 102. Then, the cooled primary cooling water is returned to the pressurized water reactor from the exit chamber 107B. On the other hand, the secondary cooling water that has exchanged heat with the high-pressure and high-temperature primary cooling water rises in the body portion 102 and is separated into steam and hot water by the steam separator 109. The separated steam is sent to the turbine after moisture is removed by the moisture separator 110.

  FIG. 8 is an explanatory diagram at the time of manufacturing the steam generator to which the joining structure according to the present embodiment is applied, and FIG. 9 is a front view at the time of manufacturing the steam generator to which the joining structure according to the present embodiment is applied. FIG.

  In manufacturing the steam generator 101 described above, as shown in FIG. 7, the barrel portion 102 includes a lower half barrel 102 </ b> A in which the tube group outer tube 103, the heat transfer tube 105, and the tube support plate 106 are accommodated. The water separator 109, the moisture separator 110, and the upper half barrel 102B in which the water supply pipe 111 is accommodated are manufactured. As shown in FIG. 8, the lower half cylinder 102A is divided into a lower cylinder 102a, an intermediate cylinder 102b, and a cone cylinder 102c from the tube plate 104 side, and these are integrally formed including the tube plate 104. Is done. When this is integrally formed, the lower half barrel 102A is used as the base material 1, and as shown in FIGS. 8 and 9, the inner circumferential surface of the lower barrel 102a near the tube plate 104 and the lower barrel 102a of the intermediate barrel 102b. A plurality of (four in the present embodiment) fan-shaped reinforcing plates (joint fittings) 2 are joined in the circumferential direction so as to maintain the perfect circles of the lower barrel 102a and the intermediate barrel 102b. Although not clearly shown in the drawing, the upper half barrel 102B includes an upper barrel in which the steam separator 109, the moisture separator 110, and the water supply pipe 111 are accommodated, and an upper lid in which the steam discharge port 112 is formed. Are formed as a base material 1, and a plurality of fan-shaped reinforcing plates are provided in the circumferential direction so as to maintain a perfect circle of the upper body with respect to the inner peripheral surface near the upper lid of the lower body. The joint hardware 2 is temporarily joined. The base material 1 is formed of low alloy steel in order to sufficiently maintain the strength of the body portion 102, and the joint hardware 2 is formed of relatively inexpensive carbon steel or stainless steel because it is a temporary joint at the time of manufacture. Has been. And as shown in FIG. 9, joining to the base material 1 of the metal fitting 2 is joined by the junction part 3 in the multiple places (4 places in this Embodiment) of the one metal fitting 2. As shown in FIG.

  FIG. 1 is a cross-sectional view of the joint structure according to the present embodiment, and FIG. 2 is a front view of the joint structure according to the present embodiment. FIG. 3 is a cross-sectional view of another joint structure according to the present embodiment.

  As shown in FIGS. 1 and 2, the joint structure of the present embodiment is the structure of the joint portion 3 described above. The joint 3 includes a low alloy steel layer 3a and a dissimilar metal layer 3b. The low alloy steel layer 3a is obtained by overlay welding a low alloy steel as a filler metal to the joint surface 1a on the base material 1 side. In addition, the dissimilar metal layer 3b is obtained by overlay welding carbon steel or stainless steel, which is a dissimilar metal, on the low alloy steel layer 3a as a filler material. The metal joint 2 is welded and joined to the dissimilar metal layer 3b with carbon steel or stainless steel filler metals 3c and 3d which are dissimilar metals. In the low alloy steel layer 3a, the inner peripheral surface of the upper half barrel 102B which is the base material 1 is formed in an arc shape in the circumferential direction, but the upper surface is flat so as to make the arc shape flat. Is formed. Moreover, since the joining structure of this Embodiment welds and joins a dissimilar metal to the base material 1 of the low alloy steel, the low alloy steel layer 3a is provided on the joining surface 1a of the base material 1, thereby the base material 1 itself. This prevents the foreign metal from being mixed into the molten portion.

  In FIG. 1 and FIG. 2, the metal joint 2 is welded and joined to the dissimilar metal layer 3 b via the positioning member 4. The positioning member 4 is made of carbon steel or stainless steel, which is a dissimilar metal, and is welded and joined to the dissimilar metal layer 3b by a filler material 3c. The metal joint 2 is welded and joined to the positioning member 4 by a filler material 3d so that the positioning member 4 is positioned at a predetermined position of the base material 1.

  In FIG. 3, the metal joint 2 is welded to the dissimilar metal layer 3b with a filler material 3c.

  Note that the metal joint 2, the dissimilar metal layer 3b, the filler metal 3c, 3d, and the positioning member 4 may be all carbon steel that is a dissimilar metal or stainless steel that is all a dissimilar metal. . In order to reduce the manufacturing cost, it is preferable to apply carbon steel which is inexpensive at all.

  4 to 6 are process diagrams of the bonding method according to the present embodiment. First, as shown in FIG. 4, overlay welding of low alloy steel is performed on the joint surface 1 a on the base material 1 side. That is, the low alloy steel layer 3 a is overlay welded to the joint surface 1 a of the base material 1. At this time, since the low alloy steel is welded, the base material 1 is preheated.

  Next, as shown in FIG. 5, build-up welding of a dissimilar metal is performed on the build-up welding surface of the low alloy steel. That is, build-up welding of the dissimilar metal layer 3b is performed on the low alloy steel layer 3a. At this time, since the welding includes low alloy steel, the low alloy steel layer 3a is preheated.

  Next, the metal joint 2 is welded to the overlay welding of the dissimilar metal. That is, the weld metal 2 is welded to the dissimilar metal layer 3b. When the joining structure shown in FIGS. 1 and 2 is adopted, as shown in FIG. 6, the dissimilar metal positioning member 4 is welded and joined to the dissimilar metal overlay welding by the dissimilar metal filler material 3c. As shown in FIG. 1, the metal joint 2 is welded to the positioning member 4 with a filler metal 3 d of a dissimilar metal. That is, as shown in FIG. 6, the positioning member 4 is welded to the dissimilar metal layer 3b with the dissimilar metal filler material 3c, and the dissimilar metal melt is bonded to the positioning member 4 as shown in FIG. The weld metal 2 is welded and joined by the additive 3d. When the positioning member 4 is welded to the dissimilar metal layer 3b with the filler metal 3c of dissimilar metal, since all are dissimilar metals, preheating is not necessary. In addition, when welding the metal joint 2 to the positioning member 4 with the filler metal 3d made of a different material, since all are made of different materials, preheating is not necessary.

  In addition, when it is set as the joining structure shown in FIG. 3, as shown in FIG. 3, the joining metal object 2 is weld-joined with the filler material 3c of a dissimilar metal with respect to overlay welding of a dissimilar metal. That is, the joint metal 2 is welded to the dissimilar metal layer 3b with the filler metal 3c of the dissimilar metal. When welding the joining hardware 2 to the dissimilar metal layer 3b with the dissimilar metal filler material 3c, since all are dissimilar metals, preheating is not required.

  As described above, the joining method of the present embodiment is low in the joining surface 1a on the base material 1 side in the joining method of welding the dissimilar metal joining hardware 2 of different materials to the base material 1 of the low alloy steel. The process of overlay welding of alloy steel, then the process of overlay welding of dissimilar metal on the overlay welding surface of low alloy steel, and then dissimilar metal for overlay welding of dissimilar metal And a step of welding and joining the metal joint 2 with the filler material.

  Here, carbon steel and stainless steel do not require preheating at the time of welding, but low alloy steel needs preheating (for example, 150 ° C.) to prevent stress cracking. And in order to weld the metal fitting 2 of carbon steel or stainless steel directly to the base material 1, it is necessary to preheat the joint metal 2 and the base material 1. Further, the lower half barrel 102A as the base material 1 has an inner diameter of several thousand mm, and the fan-shaped reinforcing plate as the joint hardware 2 joined to the inner peripheral surface of the barrel 102 to reinforce the barrel 102 is Since the weight is increased, handling the pre-heated fan-shaped reinforcing plate in the space surrounded by the trunk portion 102A is inferior in work environment and workability, and places a heavy burden on the operator. In this regard, according to the joining method of the present embodiment, the process of overlay welding of low alloy steel on the joint surface 1a on the base material 1 side, and the dissimilar metal on the overlay welding surface of the low alloy steel The step of performing the build-up welding requires preheating, but the step of welding and joining the metal joint 2 to the build-up welding of the dissimilar metal does not require preheating. As a result, since the joining hardware 2 itself is not preheated, it is possible to improve the workability of welding the joining material of the dissimilar metal to the low alloy steel.

  Further, in the joining method of the present embodiment, in the step of welding and joining the metal fitting 2, the dissimilar metal positioning member 4 is welded and joined to the overlay welding of the dissimilar metal with the filler metal 3 c of the dissimilar metal. It is preferable to weld-join the metal fitting 2 to the positioning member 4 with a filler metal 3d of a dissimilar metal.

  According to this joining method, preheating is not required when the positioning member 4 is welded and joined to the overlay welding of the dissimilar metal, and when the joining hardware 2 is welded and joined to the positioning member 4. As a result, since the positioning member 4 and the metal joint 2 are not preheated, it is possible to improve the workability of welding the metal alloy joint metal to the low alloy steel. In addition, it is possible to position the joining position of the joint hardware 2 by the positioning member 4. Furthermore, when removing the metal joint 2 from the base material 1, the metal joint 2 is easily removed from the base material 1 by deleting the filler material 3 c portion, which is the welded portion of the positioning member 4 for the overlay welding of the dissimilar metal. It is possible.

  Moreover, the joining structure of this Embodiment is build-up welding to the joining surface 1a by the side of the base material 1 in the joining structure which welds and joins the dissimilar metal joint metal 2 with a different material with respect to the base material 1 of low alloy steel. A low alloy steel layer 3a and a dissimilar metal layer 3b welded on the low alloy steel layer 3a. The metal joint 2 is welded to the dissimilar metal layer 3b by a filler metal of the dissimilar metal. It is joined.

  According to this joining structure, preheating is necessary for overlay welding of the low alloy steel layer 3a to the joining surface 1a on the base material 1 side and overlay welding of the dissimilar metal layer 3b to the low alloy steel layer 3a. However, no preheating is required for the welded joint of the metal joint 2 to the dissimilar metal layer 3b. As a result, since the joining hardware 2 itself is not preheated, it is possible to improve the workability of welding the joining material of the dissimilar metal to the low alloy steel.

  Further, in the joining structure of the present embodiment, the dissimilar metal positioning member 4 is welded to the dissimilar metal layer 3b by the dissimilar metal filler material 3c, and the dissimilar metal filler material is joined to the positioning member 4. The metal joint 2 is preferably welded and joined by 3d.

  According to this joining structure, preheating is not required for welding joining of the positioning member 4 to the dissimilar metal layer 3b and welding joining of the metal fitting 2 to the positioning member 4. As a result, since the positioning member 4 and the metal joint 2 are not preheated, it is possible to improve the workability of welding the metal alloy joint metal to the low alloy steel. In addition, it is possible to position the joint position of the joint hardware 2 by the positioning member 4. Furthermore, when removing the metal joint 2 from the base material 1, it is possible to easily remove the metal joint 2 from the base material 1 by deleting the portion of the filler material 3 c that is the welded portion of the positioning member 4 to the dissimilar metal layer 3 b. Is possible.

  Note that, in the above-described joining method and joining structure, when manufacturing the barrel 102 of the steam generator 101, the fan-shaped reinforcing plate, which is the joint hardware 2, is welded to the lower half barrel 102A, which is the base material 1, by welding. In particular, it is not limited to the base material 1 and the joint metal 2 as long as the joint metal 2 made of different materials of different materials is welded to the base material 1 of the low alloy steel. The production of the body 102 of the steam generator 101 is not limited.

DESCRIPTION OF SYMBOLS 1 Base material 1a Joining surface 2 Joined metal 3 Joining part 3a Low alloy steel layer 3b Dissimilar metal layer 3c, 3d Filler material 4 Positioning member

Claims (2)

In the joining method of welding joints of dissimilar metals of different materials to the base material of low alloy steel,
Performing overlay welding of low alloy steel on the joint surface on the base material side;
Next, a process of overlay welding of a dissimilar metal on the overlay welding surface of the low alloy steel,
Next, the step of welding and joining the joint metal with the filler metal of the dissimilar metal for the overlay welding of the dissimilar metal,
Including
In the step of welding and joining the metal fittings, the dissimilar metal positioning member is welded and joined to the dissimilar metal overlay welding with the dissimilar metal filler material, and the dissimilar metal filler material is welded to the positioning member. junction how to characterized by welding the joining hardware. Low alloy steel base material,
A low alloy rope layer bonded to the bonding surface on the base material side;
A dissimilar metal layer composed of dissimilar metals of different materials with respect to the low alloy steel and joined on the low alloy steel layer;
A dissimilar metal positioning member joined to the dissimilar metal layer with a dissimilar metal filler material ;
A metal joint made of a dissimilar metal joined to the base material via the positioning member, the dissimilar metal layer, and the low alloy steel layer by joining the positioning member with a filler metal of a dissimilar metal ,
Junction structure, characterized in that it comprises a.

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