JP5964256B2 - Duplex stainless steel structure manufacturing method and heat treatment apparatus - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method for manufacturing a duplex stainless steel structure and a heat treatment apparatus, and in particular, a method for manufacturing a duplex stainless steel structure and a heat treatment apparatus used when manufacturing a duplex stainless steel structure. About.

  Structures formed from duplex stainless steel are known. Such a structure is desired to have excellent corrosion resistance when used in, for example, a seawater pump, a seawater pipe, a valve, a casing, and the like. The welds of structures formed from duplex stainless steel are relatively inferior in corrosion resistance. It is known that the welded portion is improved in corrosion resistance by subjecting the structure to solution heat treatment (see, for example, Patent Documents 1, 2, and 3).

JP 61-212483 A JP-A-6-299234 JP 2012-172157 A

  Such a structure may be difficult to heat-treat when it is large. It is desired to improve the corrosion resistance of the welded portion of the duplex stainless steel structure more easily.

  An object of the present invention is to provide a method for producing a duplex stainless steel structure and a heat treatment apparatus that more easily produce a duplex stainless steel structure having excellent corrosion resistance.

The method for producing a duplex stainless steel structure according to the present invention provides a corrosion protection target structure formed from a duplex stainless steel, forms a part of the surface of the corrosion protection target structure, and provides a corrosion protection target structure. Solution heat treatment target part including a weld part and a heat affected part that are generated by welding an object, and there is a weld part and a heat affected part that are not solution heat treated at the lower side in the depth direction of the structure to be protected against corrosion. And heating the anticorrosion target structure so that the solution heat treatment target portion of the anticorrosion target structure is solution heat treated .

  According to such a two-phase stainless steel structure manufacturing method, the anticorrosion target structure is formed in the solution heat treatment target portion by the solution heat treatment target portion being subjected to the solution heat treatment target portion. The ratio of the γ phase and the γ phase can be formed within an appropriate range, and the σ phase can be reduced, and the surface formed by the solution heat treatment target portion of the surface of the anticorrosion target structure is prevented from corroding. be able to. Such a two-phase stainless steel structure manufacturing method further includes manufacturing another duplex stainless steel structure in which the entire structure to be protected against corrosion is solution heat-treated by solution heat treatment of only a part thereof. Compared to the method, it can be performed more easily.

The method for manufacturing a duplex stainless steel structure according to the present invention further comprises welding the corrosion-resistant structure. At this time, the solution heat treatment target portion includes a welded portion and a heat affected zone generated by welding the corrosion protection target structure, and is subjected to solution heat treatment after the corrosion protection target structure is welded.

  Such a two-phase stainless steel structure manufacturing method can prevent the heat-affected zone due to welding of the corrosion protection target structure from corroding even when the corrosion protection target structure is formed by welding. .

  The anticorrosion target structure is heated so that the solution heat treatment target portion is heated to 1050 ° C. or higher when the solution heat treatment target portion is subjected to solution heat treatment.

  According to such a two-phase stainless steel structure manufacturing method, the solution heat treatment target portion can more reliably reduce the amount of precipitation of precipitates such as σ phase on the solution heat treatment heat treatment target portion. It is possible to more reliably prevent the surface formed by the solution heat treatment target portion from being corroded.

  The anticorrosion target structure is heated so that the solution heat treatment target portion is heated to 1100 ° C. or lower when the solution heat treatment target portion is subjected to solution heat treatment.

  According to such a duplex stainless steel structure manufacturing method, the solution heat treatment target portion is formed so that the α / γ amount ratio is appropriate, and the surface formed by the solution heat treatment target portion is Corrosion can be more reliably prevented.

The solution heat treatment target portion is subjected to solution heat treatment by heating the structure to be protected against corrosion by induction heating or a laser heating device .

  According to such a two-phase stainless steel structure manufacturing method, the solution heat treatment target portion can be rapidly heated and rapidly cooled.

  The duplex stainless steel structure manufacturing method according to the present invention is adjacent to the solution heat treatment target portion of the anticorrosion target structure in parallel with the solution heat treatment target portion being subjected to the solution heat treatment. It further comprises cooling the part.

  Such a duplex stainless steel structure manufacturing method can reduce the heat-affected zone generated by the heating and prevent the periphery of the solution heat treatment target portion from corroding.

  The method for producing a duplex stainless steel structure according to the present invention has a time from the time when the solution heat treatment target part is subjected to solution heat treatment to the time when the temperature of the solution heat treatment target part becomes 700 ° C. or less. The method further includes cooling the solution heat treatment target portion so as to be less than a second.

  Deviations in the appropriate range of the α / γ amount ratio and precipitation of precipitates and intermetallic compounds reduce the corrosion resistance of the structure to be protected against corrosion. According to such a method for manufacturing a duplex stainless steel structure, the solution heat treatment target portion has less precipitation / intermetallic compound precipitation, and the surface formed by the solution heat treatment target portion is corroded. Can be prevented more reliably.

The duplex stainless steel structure according to the present invention is formed from duplex stainless steel. Duplex stainless steel structure thereof, further, the heat-treated solution heat treatment target portion solution, in the depth direction lower side of the two-phase stainless steel structure prior Symbol solution heat treatment target portion, A welded portion and a heat-affected zone that have not been subjected to solution heat treatment and a portion that has not been subjected to solution heat treatment are provided. At this time, the solution heat treatment target part forms part of the surface of the duplex stainless steel structure.

  Such a duplex stainless steel structure is produced by the duplex stainless steel structure manufacturing method according to the present invention, and the ratio of the α phase to the γ phase in the solution heat treatment target portion is within an appropriate range. And preventing the surface formed on the solution heat treatment target portion of the surface of the anticorrosion target structure from being corroded by reducing the σ phase formed on the solution heat treatment target portion. Can do.

The heat treatment apparatus according to the present invention is formed by forming a part of the surface of the anticorrosion target structure among the anticorrosion target structures formed of duplex stainless steel and welding the anticorrosion target structure. The solution heat treatment target portion including the welded portion and the heat affected zone is subjected to solution heat treatment on the lower side of the solution heat treatment portion in the thickness direction of the structure to be protected against corrosion. A heating device for heating so as to include the heat-affected zone and the weld zone that are not subjected to hydrothermal treatment, and a cooling device fixed to the heating device. At this time, the solution heat treatment target part forms part of the surface of the anticorrosion target structure. The anticorrosion target structure further includes a portion that is not subjected to solution heat treatment when the solution heat treatment target portion is subjected to solution heat treatment. The cooling device cools another part of the anticorrosion target structure adjacent to the solution heat treatment target part.

  Such a heat treatment apparatus can easily cool other portions adjacent to the solution heat treatment target portion of the structure to be subjected to solution heat treatment when the solution heat treatment target portion is subjected to solution heat treatment. For this reason, in such a heat treatment apparatus, the structure to be subjected to solution heat treatment is subjected to solution heat treatment by cooling the part of the anticorrosion target structure in parallel with heating the part to be subjected to solution heat treatment. The amount of the heat-affected zone that is sometimes generated can be reduced, and the corrosion-resistant structure can be prevented from corroding.

The heating device heats the solution heat treatment target portion by induction heating or a laser heating device .

  In such a heat treatment apparatus, the heating apparatus can be manufactured in a shape corresponding to the shape of the anticorrosion target structure, and the solution heat treatment target portion of the anticorrosion target structure having various shapes can be solution heat treated. .

  The heat treatment apparatus according to the present invention further includes another cooling device for cooling the solution heat treatment target portion.

  Such a heat treatment apparatus can cool the solution heat treatment target portion immediately after the solution heat treatment target portion is heated. For this reason, such a heat treatment apparatus can form the ratio of the α phase and the γ phase of the solution heat treatment target portion in an appropriate range, and more appropriately reduce the amount of σ phase precipitation, so that the solution treatment It can prevent more reliably that the surface which the heat treatment object part forms corrodes.

  The method for producing a duplex stainless steel structure and the heat treatment apparatus according to the present invention can more easily produce a duplex stainless steel structure having excellent corrosion resistance.

It is sectional drawing which shows the heat processing apparatus and shows the anticorrosion object structure. It is a graph which shows the influence of the ferrite content which has on the corrosion resistance of a duplex stainless steel. It is a graph which shows the structure | tissue change by the heat processing of a duplex stainless steel. It is a graph which shows the influence of the amount of precipitation of (sigma) phase on the corrosion resistance of a duplex stainless steel. It is a graph which shows the TTT curve which shows the precipitation area | region of the (sigma) phase in a duplex stainless steel.

  With reference to the drawings, an embodiment of a heat treatment apparatus will be described below. As shown in FIG. 1, the heat treatment apparatus 1 includes a support member 2, a high frequency induction heating device 3, a first cooling device 5, and a second cooling device 6. The high frequency induction heating device 3 is supported by the support member 2 by being joined to the support member 2. The high-frequency induction heating device 3 is formed of a coil, and generates predetermined magnetic field lines whose intensity changes by supplying predetermined AC power from a power source (not shown). When the high-frequency induction heating device 3 is arranged at a predetermined position with respect to the solution heat treatment target portion 8 of the structure 7 to be protected against corrosion, the solution heat treatment target portion 8 is generated by generating the magnetic lines of force. Heat.

  The 1st cooling device 5 is formed in a nozzle, and injects the compressed air and inert gas which were prepared by the cooling mechanism which is not shown in figure by being operated by the user. The first cooling device 5 is adjacent to the solution heat treatment target portion 8 in the anticorrosion target structure 7 when the high frequency induction heating device 3 is disposed at a predetermined position with respect to the solution heat treatment target portion 8. It arrange | positions in the predetermined | prescribed relative position with respect to the high frequency induction heating apparatus 3 so that the compressed air may be injected into the area | region to perform. The first cooling device 5 is supported by the support member 2 and is fixed to the high-frequency induction heating device 3 by the support member 2 so as to be disposed at a predetermined relative position.

  The 2nd cooling device 6 is formed in a nozzle, and injects the compressed air and inert gas which were produced | generated by the cooling mechanism by a user's operation or a predetermined program. The second cooling device 6 injects the compressed air or inert gas into the solution heat treatment target portion 8 when the high frequency induction heating device 3 is disposed at a predetermined position with respect to the solution heat treatment target portion 8. In this way, it is arranged at a predetermined relative position with respect to the high frequency induction heating device 3. The second cooling device 6 is supported by the support member 2 and is fixed to the high-frequency induction heating device 3 by the support member 2 so as to be disposed at a predetermined relative position thereof.

  Such a heat treatment apparatus 1 is a solution heat treatment so that only the solution heat treatment target portion 8 is heated by the high frequency induction heating device 3 based on the shapes of the anticorrosion target structure 7 and the solution heat treatment target portion 8. It is produced so that the part adjacent to the target part 8 is cooled by the first cooling device 5, and the solution heat treatment target part 8 is cooled by the second cooling device 6. Such a heat treatment apparatus 1 can be produced by producing the support member 2 in an appropriate shape, and is produced more easily than a heat treatment furnace that heats the entire structure 7 to be protected against corrosion. Can.

  The embodiment of the method for producing a duplex stainless steel structure is executed using the heat treatment apparatus 1 and includes an operation of preparing the corrosion protection target structure and an operation of heat treating the corrosion protection target structure.

  In the operation of preparing the anticorrosion target structure, first, the anticorrosion target structure 7 is produced by welding. For this reason, the base material part 10, the welded part 11, and the heat affected part 12 are formed in the anticorrosion target structure 7. The base material portion 10 is formed from a portion that is hardly affected by the heat generated by the welding. The welded portion 11 is formed of a weld metal added to the anticorrosion target structure 7 by the welding. The heat affected zone 12 is formed from a portion affected by the welding. For this reason, the heat affected zone 12 forms a region disposed between the base material portion 10 and the welded portion 11 and forms a part of the surface of the anticorrosion target structure 7. The heat-affected zone 12 has an α / γ amount ratio that falls outside the appropriate range due to the effect of heat from the welding, and a σ phase is precipitated, resulting in lower corrosion resistance than the base material portion 10. Compared to corrosion resistance is low.

  In the operation of heat-treating the anticorrosion target structure, first, the heat treatment apparatus 1 is arranged at a predetermined position so that the solution heat treatment target part 8 of the anticorrosion target structure 7 is heated by the high frequency induction heating apparatus 3. The The solution heat treatment target portion 8 is set so as to include a part of the surface formed by the anticorrosion target structure 7, and the surface formed by the solution heat treatment target portion 8 is formed by the heat affected zone 12. Set to include surface 16.

  The high frequency induction heating device 3 generates a predetermined line of magnetic force in the solution heat treatment target portion 8 by being supplied with a predetermined AC power when the heat treatment device 1 is disposed at the predetermined position. The solution heat treatment target portion 8 is heated by the generation of the magnetic lines of force to cause an eddy current to flow. When the solution heat treatment target part 8 is heated by the high-frequency induction heating device 3, the first cooling device 5 injects compressed air into a part of the anticorrosion target structure 7 adjacent to the solution heat treatment target part 8. To cool the part.

  The heat treatment apparatus 1 is heated so that the temperature of the solution heat treatment target portion 8 is included in the range of 1050 ° C. to 1100 ° C. for a predetermined time, and then the heating by the high frequency induction heating apparatus 3 is stopped. The second cooling device 6 is configured so that after the heating of the solution heat treatment target portion 8 is stopped, the time for which the temperature of the solution heat treatment target portion 8 becomes 1050 ° C. to 700 ° C. or less is less than 100 seconds. Is injected onto the solution heat treatment target portion 8 to cool the solution heat treatment target portion 8.

  As the anticorrosion target structure 7 is heated in this manner, the solution heat treatment target portion 8 is subjected to solution heat treatment. The surface formed by the solution heat treatment target portion 8 is formed on the surface formed by the heat affected zone 12 by reducing the amount of the σ phase and the like by the solution heat treatment target portion 8 being solution heat treated. In comparison, the corrosion resistance is excellent. For this reason, according to such a duplex stainless steel structure manufacturing method, the corrosion resistance of the anticorrosion target structure 7 is improved.

  When performing the solution heat treatment on the entire structure 7 to be protected, it is necessary to prepare a large heat treatment furnace capable of arranging the entire structure 7 to be protected. Furthermore, the anticorrosion target structure 7 needs to be treated so as not to be thermally deformed when the whole structure is heated. Such a duplex stainless steel structure manufacturing method heats the solution heat treatment target part 8 so that the part 14 different from the solution heat treatment target part 8 of the corrosion prevention target structure 7 is not subjected to the solution heat treatment. Therefore, it is not necessary to prepare such a large heat treatment furnace, and the labor for making care to prevent thermal deformation is reduced. For this reason, such a duplex stainless steel structure manufacturing method is more easily executed as compared with other duplex stainless steel structure manufacturing methods that heat the entire corrosion-resistant structure 7. Can.

  As the anticorrosion target structure 7 is heated in this way, a heat affected zone 15 is formed between the solution heat treatment target portion 8 and the portion 14 not subjected to the solution heat treatment. The heat-affected zone 15 is formed from a portion affected by heat due to the heating, and has a low corrosion resistance in the same manner as the heat-affected zone 12. When the solution heat treatment target portion 8 is being heated, the portion 7 adjacent to the solution heat treatment target portion 8 is cooled by the first cooling device 5 so that the solution heat treatment target portion 8 is The temperature gradient around the area becomes steep, and the heat affected zone 15 becomes smaller. For this reason, as for the corrosion prevention object structure 7, the area of the surface 17 formed of the heat affected zone 15 becomes small, and corrosion resistance improves.

  The duplex stainless steels of steel types SUS329J1, steel type SUS329J3L, steel type SUS329J4L, steel type UNS S82122, and steel type UNS S32304 are subjected to solution heat treatment by heating to 950 ° C. to 1100 ° C. and then rapidly cooling. The duplex stainless steel further has a temperature at which the α phase precipitates at 600 ° C to 1000 ° C, a temperature at which the nitride precipitates at 700 ° C to 1000 ° C, and a temperature at which the carbide precipitates at 600 ° C to 1050 ° C. It is. For this reason, in such a method for producing a duplex stainless steel structure, the solution heat treatment target portion 8 is solution formed by heating the solution heat treatment target portion to 1050 ° C. or more and 1100 ° C. or less. Heat treatment can be performed, and the amount of α phase, nitride, and carbide precipitated in the solution heat treatment target portion 8 can be reduced. As a result, such a method for producing a duplex stainless steel structure can improve the corrosion resistance of the surface formed by the solution heat treatment target portion 8, and the α / γ amount ratio is in an appropriate range. It becomes possible to improve the corrosion resistance of the anticorrosion target structure 7 as compared with other welding materials in which the method for producing a duplex stainless steel structure is not executed.

  FIG. 2 shows a relationship indicating the effect of the amount of ferrite (α) on the corrosion resistance of the duplex stainless steel. The relation 31 indicates the pitting corrosion speed with respect to the ferrite content. The pitting corrosion rate corresponding to a certain amount of ferrite indicates a rate at which pitting corrosion proceeds in a duplex stainless steel when a ferrite phase having the ferrite amount is precipitated in a certain duplex stainless steel. The relation 31 indicates that the pitting corrosion rate is smaller as the ferrite amount is approximately 50%. The relation 31 further indicates that the duplex stainless steel has a predetermined corrosion resistance when the ferrite content is included in a range of 50% to 75% in the duplex stainless steel.

  FIG. 3 shows a relationship showing the structural change of the duplex stainless steel by heat treatment. The relationship 32 indicates the ferrite content (α / γ content ratio) corresponding to the heating temperature at which the solution heat treatment is performed on the duplex stainless steel of the steel type SUS329J1. The relation 32 shows that the amount of ferrite in which the ferrite phase precipitates in the duplex stainless steel is included in the range of 50% to 75% by solution heat treatment of the duplex stainless steel at 1100 ° C. or less. . That is, the relation 31 and the relation 32 indicate that the duplex stainless steel has a predetermined corrosion resistance by subjecting the duplex stainless steel of the steel type SUS329J1 to solution heat treatment at 1100 ° C. or less.

  FIG. 4 shows the relationship indicating the influence of the σ phase precipitation amount on the corrosion resistance of the duplex stainless steel. The relationship 34 shows the σ phase area ratio corresponding to the aging time at 800 ° C. The σ phase area ratio corresponding to a certain aging time indicates the amount of σ phase precipitated in the duplex stainless steel when the duplex stainless steel of the steel type SUS329J4L is held at 800 ° C. for the aging time. When the phase stainless steel is cut in a plane, the ratio of the cross-sectional area of the cross section where the σ phase precipitated in the duplex stainless steel is cut by the area of the cut surface where the duplex stainless steel is cut is shown. ing. Relation 34 shows that the longer the aging time is, the larger the σ phase area ratio is, and the longer the aging time is, the larger the amount of σ phase precipitated in the duplex stainless steel.

  FIG. 4 further shows the relationship between the aging time and the pitting potential. The relationship 35 shows the pitting potential corresponding to the aging time. The pitting potential corresponding to a certain aging time is such that when a duplex stainless steel of SUS329J4L, which is kept at 800 ° C. only for that aging time, is immersed in artificial seawater at 80 ° C., the pitting corrosion occurs in the duplex stainless steel. The potential generated is shown. Relation 35 indicates that the longer the aging time is, the smaller the pitting potential is, and the longer the aging time is, the more easily the duplex stainless steel is corroded. That is, the relationship 34 and the relationship 35 indicate that the smaller the amount of the σ phase precipitated on the duplex stainless steel, the better the corrosion resistance of the duplex stainless steel.

  FIG. 5 shows the precipitation region of the σ phase in the duplex stainless steel of the steel type SUS329J4L. The precipitation region 36 more reliably prevents the σ phase and the like from precipitating in the solution heat treatment target portion 8 by rapidly cooling the solution heat treatment target portion 8 from 1100 ° C. to 700 ° C. in less than 100 seconds. It shows that you can. That is, the relationship 34, the relationship 35, and the precipitation region 36 are obtained by rapidly cooling the solution heat treatment target portion 8 from 1100 ° C. to 700 ° C. in less than 100 seconds, that is, the above-described duplex stainless steel product. It shows that the surface formed by the solution heat treatment target portion 8 can be prevented from corroding by the structure manufacturing method.

  The precipitation region varies depending on the type of duplex stainless steel. For this reason, even if the solution heat treatment target portion 8 is slowly cooled to 700 ° C. over 100 seconds, there may be a steel type in which the σ phase or the like does not precipitate in the solution heat treatment target portion 8. The two-phase stainless steel structure manufacturing method can slowly cool the solution heat treatment target portion 8 over 100 seconds when the corrosion protection target structure 7 is formed of such a steel type. Also in this case, the corrosion resistance of the anticorrosion target structure 7 is improved by the solution heat treatment target portion 8 being solution heat treated.

  FIG. 3 further shows the relationship showing the structural change due to the heat treatment of the steel type SUS329J4L. The relationship 33 indicates the amount of ferrite corresponding to the heating temperature at which a solution heat treatment is performed on the duplex stainless steel of the steel type SUS329J4L. Relation 33 shows that even when the duplex stainless steel is subjected to solution heat treatment at 1100 ° C. or higher, the ferrite content in which the ferrite phase precipitates in the duplex stainless steel is included in the range of 50% to 75%. . That is, the relationship 32 and the relationship 33 indicate that the heating temperature appropriate for the steel type of the duplex stainless steel is different. Even when the solution heat treatment target portion 8 is heated to 1100 ° C. or higher, the corrosion prevention target structure 7 It shows that the corrosion resistance can be improved. The duplex stainless steel structure manufacturing method includes a solution heat treatment target by heating the solution heat treatment target portion 8 to 1100 ° C. or higher when the corrosion prevention target structure 7 is formed of such a steel type. The part 8 can also be solution heat treated. Also in this case, the corrosion resistance of the anticorrosion target structure 7 is improved by the solution heat treatment target portion 8 being solution heat treated.

  In another embodiment of the heat treatment apparatus, the high-frequency induction heating apparatus 3 in the above-described embodiment is replaced with another heating apparatus that heats the solution heat treatment target portion 8 using a method other than induction heating. be able to. Examples of the heating device include a laser heating device that heats the solution heat treatment target portion 8 by irradiating the solution heat treatment target portion 8 with a laser. The heat treatment apparatus provided with such a heating apparatus can perform solution heat treatment on the solution heat treatment target portion 8 more easily and in the same manner as the heat treatment apparatus 1 in the above-described embodiment, and has excellent corrosion resistance. A structure made of phase stainless steel can be more easily produced.

  In addition, the 1st cooling device 5 and the 2nd cooling device 6 can also cool the anticorrosion object structure 7 using the other cooling gas different from compressed air. As the cooling gas, an inert gas exemplified by nitrogen and the atmosphere are exemplified. Even when such a cooling gas is used, the first cooling device 5 and the second cooling device 6 can appropriately cool the anticorrosion target structure 7 as described above.

  In addition, the duplex stainless steel structure manufacturing method can also be used to improve the corrosion resistance of other regions different from the heat-affected zone by welding. An example of the region is a portion that has undergone phase transformation due to the application of stress. In the method for producing a duplex stainless steel structure, the solution heat treatment target part 8 is set so that the solution heat treatment target part 8 includes such a region, so that the region is more easily subjected to solution heat treatment. And the corrosion resistance of the surface formed by the region can be improved more easily.

1: Heat treatment device 3: High frequency induction heating device 5: First cooling device 6: Second cooling device 7: Corrosion protection target structure 8: Solution heat treatment target portion 10: Base material portion 11: Welded portion 12: Heat affected zone

Claims (8)

Preparing an anticorrosion target structure formed from duplex stainless steel;
Welding the anticorrosion target structure;
A part of the surface of the anticorrosion target structure is formed, and includes a welded portion and a heat-affected zone generated by welding the anticorrosion target structure, and the depth direction lower side of the anticorrosion target structure Setting a solution heat treatment target part so that there is a welded part and a heat-affected part that are not solution heat-treated, and
The anticorrosion target structure is heated using an induction heating device or a laser heating device so that a solution heat treatment target portion of the anticorrosion target structure is subjected to solution heat treatment after the corrosion protection target structure is welded. duplex stainless steel structure production method and a this. The anticorrosion objective structure, when the solution heat treatment target portion is solution heat treated, the so solution heat treatment target portion is heated above 1050 ° C., two as described in claim 1 is heated Phase stainless steel structure manufacturing method. The anticorrosion objective structure, when the solution heat treatment target portion is solution heat treated, the so solution heat treatment target portion is heated to 1100 ° C. or less, in claim 1 or claim 2 is heated A method for producing a duplex stainless steel structure as described. In parallel to the solution heat treatment target portion is solution heat treated, the claims 1 to 3, further comprising cooling the portion adjacent to the solution heat treatment target part of the anticorrosion objective structure A method for producing a duplex stainless steel structure according to any one of the above. The solution heat treatment target part is cooled so that the time from the time when the solution heat treatment target part is subjected to solution heat treatment to the time when the temperature of the solution heat treatment target part becomes 700 ° C. or less is less than 100 seconds. The duplex stainless steel structure manufacturing method according to any one of claims 1 to 4 , further comprising: It is a structure made of duplex stainless steel formed from duplex stainless steel,
A solution heat treatment target portion that has been solution heat treated, and
On the lower side in the depth direction of the two-phase stainless steel structure of the solution heat treatment target part, a welded portion and a heat affected zone that were not solution heat treated,
The solution heat treatment target part is a duplex stainless steel structure that forms part of the surface of the duplex stainless steel structure. Among the anticorrosion target structures formed from duplex stainless steel, a welded portion and a heat affected zone that are formed by forming a part of the surface of the anticorrosion target structure and welding the anticorrosion target structure. A heat-affected zone that is not subjected to a solution heat treatment when the solution heat treatment target portion is subjected to a solution heat treatment on the lower side in the thickness direction of the structure to be protected against corrosion. A heating device for heating to include a weld ,
A cooling device fixed to the heating device,
The cooling device cools another part of the anticorrosion target structure adjacent to the solution heat treatment target part ,
The heating apparatus is a heat treatment apparatus that is an induction heating apparatus or a laser heating apparatus. The heat treatment apparatus according to claim 7 , further comprising another cooling device that cools the solution heat treatment target portion.

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