KR20100049087A - Deteriorated portion reproducing method and deteriorated portion reproducing device - Google Patents

Abstract

An object is to provide a deteriorated portion reproducing method and a deteriorated portion reproducing device for easily and certainly repairing and reproducing a deteriorated portion generated in a metal member and certainly extending the life of the metal member. A local heating process for locally heating a deteriorated portion (C) using a main heater (25) and allowing the deteriorated portion (C) to be pressure-welded using compression force generated by heat expansion and a periphery heating process for heating the neighborhood of the periphery of a region (HA1) heated in the local heating process using a sub heater (26) are performed. Then, a cooling process for simultaneously cooling the region (HA1) heated by use of the main heater (25) and a region (HA2) heated by use of the sub heater (26) is performed.

Description

Regeneration method of deterioration part and regeneration device of deterioration part {DETERIORATED PORTION REPRODUCING METHOD AND DETERIORATED PORTION REPRODUCING DEVICE}

The present invention relates to a regeneration method which is very suitable for regenerating a deterioration part due to creep generated in a metal member constituting a high-temperature pipe used for a boiler or a turbine of, for example, a thermal power plant or a nuclear power plant.

In recent years, for example, in high-temperature piping used in boilers and turbines of thermal and nuclear power plants, chemical plants, and the like, the operation time is long, depending on the name of the equipment. Due to the thermal fatigue due to sufficient maintenance management becomes more and more important.

For example, in large-diameter thick pipes in which a high temperature resistant metal member is used, nondestructive inspection such as a histological examination and an ultrasonic examination is regularly performed in order to detect degradation early in the metal member and the welded portion thereof. And the deterioration part is repaired based on the result of the non-destructive inspection.

Here, as a technique for repairing a metal member, a technique in which a heat treatment is locally performed using a high frequency heating coil for a creep void or a cracked deterioration part, and the creep void or crack is pressed against and regenerated by the internal pressure of thermal expansion (for example, For example, refer patent document 1).

Japanese Patent Laid-Open No. 2003-253337

As shown in FIG. 8A, the regeneration technique described in Patent Document 1 locally heats the region including the deterioration portion C by the heater 1 made of a high frequency heating coil. The region where the temperature rises by this heating is called the heating region 3. At this time, since the temperature rise does not occur around the heating area 3 of the metal member 2, the heating area 3 can interfere with the thermal expansion, and a compressive stress is generated. Therefore, the deterioration part C, such as a creep void and a crack which exist in the heating area | region 3, extinguishes by being crimped | bonded by this compressive stress. In order to enlarge the compressive stress of this void welding process, it is effective to make the temperature of the heating area | region 3 as high as possible. However, when the temperature of the heating region 3 is increased, the outer surface of the metal member 2 in the vicinity of the heater 1 dissolves, and thus the heating temperature cannot be arbitrarily increased. In addition, as shown in FIG. 8B, in the process of cooling the region after the heat treatment, the heating region 3 shrinks. At this time, since the circumference | surroundings of the heating area | region 3 restrains shrinkage | contraction of the heating area | region 3, tensile stress arises in the heating area | region 3. Therefore, the deterioration part C once crimped may open. Moreover, there exists a possibility that tension residual stress may generate | occur | produce in the heating area | region 3 after repair, and it cannot wish to maintain a repair state for a long term. In addition, although the crystal structure is coarsened by the void welding process, there is a fear that the coarse hardened structure may remain only in the heat cycle of raising and lowering the temperature along the transformation point in the subsequent recrystallization heat treatment, and it is necessary to perform sufficient recrystallization. There is.

Therefore, in order to reliably regenerate the deterioration part C, the pressure contact stress at the time of heating is taken large enough, the residual tensile stress at the time of cooling is reduced, and the coarse hardened structure is fully recrystallized to the structure equivalent to a base material. It is necessary.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method for regenerating a deterioration portion capable of easily and reliably maintaining, repairing, and repairing a deterioration portion formed on a metal member over a long period of time to extend the life of the metal member. It aims to provide. In addition, an object of the present invention is to provide a regeneration device of the deterioration unit that can perform the regeneration method of the deterioration unit.

In order to achieve the above object, the regeneration method of the deterioration portion of the present invention, in the method for regenerating the deterioration portion formed on the metal member, heating the local region including the deterioration portion to form a first heating region, The predetermined time from the start of the heating in the first heating step during the first heating step of pressing the deterioration part by the compressive stress to the first heating area due to the restraint of thermal expansion and the first heating area After passing, the 2nd heating process of forming a 2nd heating area | region by heating the periphery of a 1st heating area | region is characterized by including the.

According to the present invention, by heating the deterioration part locally by the first heating step, and heating the periphery of the first heating area by the second heating step, the thermal expansion force of the heating portion around the first heating area is increased. Pressure acts on the first heating region, and compressive stress acting on the deterioration portion increases. Further, the deterioration portion is compared with the case where the first heating region and the second heating region are simultaneously heated by performing the second heating process after sufficiently creep relaxation of the compressive stress in the first heating region prior to the first heating process. The compressive stress increases, and the deterioration part is reliably pressed. That is, in this invention, the compressive stress is further provided to a 1st heating area | region by the thermal expansion of a 2nd heating area | region.

In this invention, it is preferable to continue a 1st heating process and a 2nd heating process for predetermined time. This is because the heat added from the outside by heating is sufficiently raised to the inside of the thick portion of the metal member by heat conduction, and the deterioration portion is reliably pressed.

The metal member aimed at by this invention prepares the base metal and the weld metal which connects a base material normally, and a deterioration part exists in the heat affected part of the base material produced by welding. In many cases, the base material portion except the heat affected portion does not deteriorate as much as the heat affected portion. In that case, the first heating zone is formed including the heat affected zone. And it is preferable that a 2nd heating area is formed in the base material part adjacent to a heat-affecting part. The base material portion other than the heat affected portion has less deterioration than the heat affected portion, and even if the residual tensile stress caused by the regeneration treatment acts, it usually has a sufficient lifetime. In addition, since the weld metal may have a void caused by creep damage, when this region is heated, there is a risk that tensile stress is applied during cooling to accelerate the damage. Therefore, it is preferable to avoid making the part of a weld metal the object of a 1st heating area | region and a 2nd heating area | region.

In the present invention, it is preferable to include a cooling step of synchronizing cooling of the first heating region and cooling of the second heating region. By doing in this way, in the area | region which matched the 1st heating area | region and the 2nd heating area | region, it receives the tensile stress which arises at the time of cooling. This is because the absolute tensile stress is lowered when the tensile stress is applied in the region where the first heating region and the second heating region are aligned as in the present invention as compared with the case of FIG. 8 that is subjected to the tensile stress only in the first heating region. Therefore, there is a low possibility that the deteriorated portion once pressed in is opened again, and the tensile residual stress acting on the deteriorated regenerated portion during unit operation after regeneration can be reduced.

After completion of the cooling step, it is preferable to perform recrystallization heat treatment on the regeneration treatment point where the first and second heat treatments are applied to the metal member. Recrystallization heat processing is a process which repeats the process which heats a metal member more than its transformation point, and cools below its transformation point multiple times. By performing this treatment, the voids, precipitates, or grain boundary segregation existing along the grain boundaries of the structure are trapped in the mouth, and the crack propagation speed is slowed, and the damage growth speed can be reduced. In addition, by performing the isothermal vacancy transformation process in this heating and cooling process, coarse hardened structures generated in the regeneration process can be lost. Therefore, in the place which performed the regeneration process, the factor which inhibits fracture ductility is suppressed and favorable ductility can be obtained.

The present invention relates to a device for regenerating a deterioration portion formed on a metal member so that the above regeneration method can be implemented, the first heater being disposed at a position facing the deterioration portion and locally heating the deterioration portion, and heating by the first heater. A regenerator of the deterioration unit is provided, comprising a second heater for heating the circumference of the region.

In this apparatus, the heating by the first heater is preceded by the heating by the second heater, thereby heating and cooling the temperature of the deterioration portion and the surroundings of the metal member while appropriately controlling the temperature, thereby making it optimal for the deterioration portion. The heat treatment can be easily performed.

This invention performs the isothermal vacancy transformation process in the heating and cooling process which heats a metal member more than transformation point, and cools below transformation point, and repeats heating and cooling process several times, and raises and lowers the temperature along a transformation point, It is characterized by the above-mentioned. The recrystallization heat treatment method can be performed independently.

As a result, the portion regenerated by heat treatment becomes a ductile-rich structure by the heating and cooling step after the heat treatment, and the voids, precipitates or grain boundary segregation existing along the grain boundaries of the structure are trapped in the mouth and the crack propagation rate is increased. It slows down, a damage propagation rate falls, and coarse hardened structure disappears by an isothermal vacancy transformation process, the inhibition of fracture ductility is suppressed, and more favorable ductility can be obtained.

According to the regeneration method of the deterioration part of the present invention, a large compressive stress can be exerted on the deterioration part by heating the surroundings of the deterioration part later than the heating of the deterioration part. In addition, by cooling the deterioration part and its surroundings synchronously, it is possible to disperse the tensile stress generated in the deterioration part at the time of cooling widely, and the influence on the regeneration point of the tensile stress can be suppressed as much as possible.

As a result, the residual stress of tensile strength at the regeneration point can be reduced, and the life of the metal member can be extended.

In addition to the heating / cooling step of transforming the regeneration treatment point a plurality of times, an isothermal vacancy transformation step of holding the regeneration treatment point at a predetermined temperature for a predetermined time and continuing transformation is also present depending on the grain boundary of the structure. The voids, precipitates or grain boundaries that are present can be trapped in the mouth. Furthermore, coarse hardened structure can be dissipated, inhibition of fracture ductility can be suppressed, and good ductility can be obtained. As a result, the rate of damage propagation can be lowered by slowing down the crack propagation rate.

In addition, according to the regeneration device of the deterioration part of the present invention, since the first heater and the second heater are provided, the deterioration part formed in the metal member and its surroundings are appropriately controlled by controlling the temperature of the first heater and the second heater. It is possible to easily perform heat treatment that is optimal for heating, cooling, and regenerating a deterioration portion while controlling temperature.

1 is a perspective view showing a playback device according to an embodiment of the present invention;
2 is a diagram showing the positional relationship of heaters at the time of regeneration by the reproducing apparatus;
3 is a cross-sectional view showing an arrangement state of a heater with respect to a regeneration point;
4 is a graph showing a change in temperature during regeneration;
5 is a view for explaining a regeneration method of the deterioration unit, (a) is a cross-sectional view showing a state of heating by the main heater, (b) is a cross-sectional view showing a state of heating by the main heater and the sub-heater. ,
6 is a graph showing changes in temperature and changes in metal structure during recrystallization heat treatment in the regeneration method according to the present embodiment;
7 is a photomicrograph of the HAZ portion 15, (a) is a photomicrograph before regeneration heat treatment, (b) is a photomicrograph after regeneration heat treatment,
8 is a view for explaining a conventional regeneration method, (a) is a cross-sectional view showing a state of heating, (b) is a cross-sectional view showing a cooling process state.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the reproduction | regeneration method and apparatus of the deterioration part which concerns on this invention is described with reference to drawings.

1 is a perspective view showing a reproduction device according to an embodiment of the present invention. 2 is a diagram showing the positional relationship of heaters when a regeneration method is performed by a regeneration device. 3 is a cross-sectional view showing an arrangement state of a heater with respect to a regeneration point.

As shown in FIG. 1, this regeneration apparatus 11 is attached to the piping 12 which becomes a low alloy steel pipe, for example.

Here, as shown in FIG. 2 and FIG. 3, in the high-temperature pressure-resistant welding part (metal member) 14 in which the pipes 12 are welded to each other by the weld metal 13, the weld metal 13 and each pipe ( The HAZ portion (heat affected zone: Heat Affected Zone) 15 is generated by the heat effect when the weld metal 13 is welded to the boundary with 12). And in this high temperature-resistant welding part 14, deterioration part C, such as a creep void and a crack, may generate | occur | produce in the HAZ part 15 by long-term use. For this reason, especially the intensity | strength of the HAZ part 15 falls, and it becomes a factor, such as a break in the high temperature proof pressure welding part 14.

Here, as the material of the pipe 12, for example, low alloy steels having a Cr content of 3% or less (not including 0) and a Mo content of 2% or less (not including 0) (STPA22, STPA23) , STPA24). As the material of the weld metal 13, for example, the Cr content of the material of the pipe 12 and the metallurgy is 3% or less (not including 0), and the Mo content is 2% or less (not including 0). There is no). Of course, the present invention is not limited to the materials listed above, and can be applied to various other materials.

Here, in this embodiment, a case where the regeneration device 11 is attached to the pipe 12 and the high temperature withstand pressure welding part 14 in which the deterioration part C was formed in the HAZ part 15 is demonstrated as an example is demonstrated. do.

In the regeneration device 11, a main heater (first heater) 25 and a sub heater (second heater) 26 each made of a high frequency heating coil are arranged in parallel with an interval therebetween. These main heater 25 and the sub heater 26 are flat plate shape, and are arrange | positioned along the outer peripheral surface of the piping 12, with the regeneration apparatus 11 attached to the piping 12. FIG.

The main heater 25 has the position (deterioration part C) which opposes the boundary part of the piping 12 and the welding metal 13 in the state in which the regeneration device 11 is arrange | positioned along the outer peripheral surface of the piping 12. Facing position). In addition, the sub heater 26 is disposed to face the pipe 12 at a position deviating from the boundary between the pipe 12 and the weld metal 13. That is, the sub heater 26 is arrange | positioned so that it may face the part deviating from the boundary part of the piping 12 and the welding metal 13 around the heating area by the main heater 25. As shown in FIG. Thereby, the regeneration device 11 can heat the high temperature withstand pressure welding part 14 including the heating area HA1 (FIG. 5) by the main heater 25, and the wide range around it. In addition, these main heater 25 and the sub heater 26 are not limited to flat plate shape, but may be ring-shaped or circular arc shape which reach the periphery of the piping 12 whole.

In addition, the regeneration device 11 includes a water cooling tube 27 and a power cable 29 for coil cooling. The main heater 25 and the sub heater 26 are controlled so that the member surface temperature detected by the thermocouple mounted on the member surface immediately below each heater becomes a predetermined temperature.

Next, the procedure for regenerating the high temperature withstand pressure welding part 14 of the piping 12 using the said regeneration device 11 is demonstrated.

In the present embodiment, the regeneration heat treatment and the recrystallization heat treatment are performed by the regeneration apparatus 11.

(Regeneration heat treatment)

First, the regenerative heat treatment will be described. 4 is a graph showing a temperature change during regeneration heat treatment, and FIG. 5 is a cross-sectional view illustrating a regeneration method of the deterioration portion.

(1) pretreatment process

First, the oxide film of the high temperature withstand pressure welding part 14 which is a maintenance target part is removed as needed.

Next, the main heater 25 is disposed at a position facing the boundary between the pipe 12 and the weld metal 13. In this way, the sub heater 26 is disposed so as to face the pipe 12 at a position deviating from the boundary between the pipe 12 and the weld metal 13.

(2) Local heating step (first heating step)

In this state, first, as shown by the solid line in FIG. 4, the surface of the boundary member of the piping 12 of the high temperature-pressure-resistant welding part 14, and the welding metal 13 by the main heater 25 is temperature T1. Rapid heating to (for example, heating to 1050 to 1250 ° C, preferably 1200 ° C in 10 minutes). Moreover, it is preferable to make this temperature T1 higher than the transformation point of a material (for example, transformation point A3 transformation point of (alpha) -Fe and (gamma) -Fe).

Thereby, thermal expansion of a heating part arises in the heating area | region (1st heating area | region) HA1 by the main heater 25 in the high temperature-pressure-resistant welding part 14. At this time, since the circumference | surroundings of the heating area | region HA1 are not thermally expanding, a restraint force is exhibited with respect to the thermal expansion of the heating area | region HA1. Therefore, the compressive stress acts on the heating region HA1 due to its thermal expansion and restraint around. By this compressive stress, the deterioration part C which consists of creep voids etc. is press-contacted. The compressive stress acting on the heating area HA1 is shown by the arrow in FIG.

(3) ambient heating process (second heating process)

After the heating by the main heater 25 is started and a predetermined time has elapsed, the heating by the sub heater 26 is started while the heating by the main heater 25 is continued, and the main heater 25 is started. The vicinity of the heating area HA1 by is heated to the temperature T1 by the profile shown by the broken line in FIG. Heating by the sub heater 26 is started after 300 second, for example, after the member surface immediately under the main heater 25 reaches the target temperature (temperature T1).

In this manner, thermal expansion occurs in the heating region (second heating region) HA2 of the pipe 12 heated by the sub heater 26. And the heating part of the heating area | region HA2 is restrained because the base material part on the opposite side (right side in FIG. 5) to the side adjacent to the heating area | region HA1 does not thermally expand. Thereby, the pressure by the thermal expansion force of the heating part of this heating area | region HA2 acts as a compressive stress on the heating area | region HA1 softened by the heating by the main heater 25. As shown in FIG. Therefore, the pressure contact effect of the deterioration part C can be improved. In order to acquire this effect, it is necessary to continue local heating process and ambient heating process for predetermined time. The compressive stress acting on the heating area HA1 is shown by the arrow in FIG.

In addition, the high temperature breakdown pressure including the heating area HA1 of the repair point by the main heater 25 by the synergistic effect of the heating by the main heater 25 by performing heating by this sub heater 26 is performed. The weld 14 and the wide area around it are heated. As the heating range is widened in this manner, the tensile stress in the subsequent cooling process is reduced.

(4) cooling process

As described above, if the heating of the surrounding heating region HA2 by the sub heater 26 is continued for a predetermined time after the local heating of the heating region HA1 by the main heater 25, the illustrated in FIG. 4 is shown. As described above, the heating temperature by the main heater 25 and the sub heater 26 is lowered in synchronization. In addition, the cooling rate is preferably about 50 ° C / hr, for example. In this way, a wide range including the regeneration point of the high temperature withstand pressure welding part 14 is cooled slowly.

Thereby, since the tensile stress which arises at the time of cooling is disperse | distributed to the wide range of the high temperature-pressure-resistant welding part 14, ie, the area containing at least the heating area | region HA1 and the heating area | region HA2, the absolute value is heated area | region HA1. ) Is lower than if only exist. Therefore, the influence on the regeneration point of the tensile stress by heat shrink in a cooling process is suppressed as much as possible.

This eliminates the inconvenience that the deteriorated portion C which is press-contacted is opened or the tensile residual stress is generated in the high temperature withstand pressure welded part 14, and the maintenance state of the high temperature withstand pressure welded part 14 is maintained for a long period of time. It is possible to extend the life of 12).

(Recrystallization heat treatment)

Next, the recrystallization heat treatment will be described. 6 is a graph showing changes in temperature and changes in metal structure during recrystallization heat treatment in the regeneration method according to the present embodiment.

The metal structure of the regeneration point cooled gently by the above-mentioned regeneration heat treatment becomes a bainite structure in which a part contains ferrite, as indicated by a1 in FIG. 6.

(1) heating process

In the recrystallization heat treatment, the regeneration point is first heated by the main heater 25 to a temperature T3 (for example, 900 to 950 ° C, preferably about 930 ° C) exceeding the A3 transformation point, and a predetermined time (for example, 30 to 120 minutes, preferably 60 minutes). This heat treatment causes the metal structure of the regeneration point to become an austenite structure, as indicated by reference numeral a2 in FIG. 6. At this time, a coarse hardened structure formed at the time of regeneration heat treatment remains in the metal structure. And this coarse hardened structure may impair ductility at break.

(2) isothermal vacancy transformation process

Next, the temperature control of the main heater 25 is carried out, and the regeneration point is cooled to a temperature T4 (for example, 680 to 730 ° C, preferably about 700 ° C) lower than the A3 transformation point, and a fixed time ( For example, the isothermal vacancy transformation process is carried out by holding for 180 minutes to 600 minutes, preferably 300 minutes. This heat treatment transforms the austenite structure into a vacancy. Therefore, as shown by a3 in FIG. 6, the metal structure at the regeneration point becomes a ferrite pearlite structure in which ferrite and pearlite are vacated, and coarse hardened structure disappears.

Here, if the holding temperature of the isothermal vacancy transformation is lower than the nose of the isothermal vacancy transformation, the isothermal vacancy transformation requires a long time for the isothermal vacancy transformation, and if it exceeds this greatly, the isothermal vacancy transformation becomes difficult at the regeneration point. Therefore, as temperature T4 hold | maintained in an isothermal vacancy transformation process, the temperature which can smoothly isothermal vacancy transformation of the metal structure of a regeneration point is preferable.

In addition, as time to hold | maintain with temperature T4 in an isothermal vacancy transformation process, what is necessary is just time to complete the isothermal vacancy transformation in the area | region where the crystal grain coarsened in the said 1st heating process and the 2nd heating process.

(3) heating process

The regeneration point is heated again by the main heater 25 to the temperature T3 exceeding the A3 transformation point, and held for a predetermined time (for example, 30 to 120 minutes, preferably 60 minutes). In this heat treatment, the metal structure at the regeneration point is again austenite structure, as indicated by a4 in FIG. 6. At this time, since the coarse hardened structure disappears in the previous isothermal vacancy transformation process, the metal structure becomes an austenite structure without this coarse hardened structure.

(4) cooling process

Next, the regeneration point is cooled to a temperature T5 sufficiently lower than the A3 transformation point (for example, 550 to 650 ° C, preferably about 500 ° C). By this heat treatment, the regeneration point is a metal structure in which a part of the austenite structure is vacated by ferrite and pearlite, as indicated by reference numeral a5 in FIG. 6.

(5) heating process

The regeneration point is heated again by the main heater 25 to the temperature T3 exceeding the A3 transformation point, and held for a predetermined time (for example, 30 to 120 minutes, preferably 60 minutes). In this heat treatment, the metal structure at the regeneration point is again austenite structure, as indicated by a6 in FIG. 6.

(6) cooling process

Thereafter, the main heater 25 is temperature controlled, and the regeneration point is cooled at a predetermined cooling rate (for example, about 50 ° C./hr).

By cooling in this way, as shown by aa in FIG. 6, as for the metal structure of a regeneration point, austenite structure is continuously cooled and transformed, and as shown by aa in FIG. And ferrite pearlite structure including bainite.

In the recrystallization heat treatment, by controlling the temperature of the main heater 25, the regeneration point is heated and cooled, and the transformation process is repeated a plurality of times, so that the regeneration point is the same as that of the piping 12 having the base metal. It becomes rich ferrite pearlite structure. In addition, by the recrystallization heat treatment, voids, precipitates or grain boundary segregation existing in the mouth at the time of welding are trapped in the mouth, so that the crack propagation speed is slowed and the damage growth speed can be decreased. In addition, since the coarse hardened structure disappears by the isothermal vacancy transformation step performed in the recrystallization heat treatment process, inhibition of fracture ductility is suppressed, and good ductility can be obtained.

As described above, according to the regeneration method of the deterioration portion according to the present embodiment, the pressure due to the thermal expansion force of the heating portion formed of the heating region HA2 around the deterioration portion C is reduced. It can act on the heating area | region HA1. Thereby, the deterioration part C can be reliably crimped | bonded by a high compressive force, and it can regenerate well over the thickness of the heating area HA1 of the deterioration part C, and can aim at the improvement of regeneration quality. Can be.

Moreover, since the deterioration part C and its surroundings are simultaneously cooled, it is possible to disperse the tensile stress generated in the deterioration part C at the time of cooling extensively, and the influence on the regeneration point of the tensile stress can be suppressed as much as possible. . In addition, the inconvenience of generating tensile residual stress at the regeneration point is eliminated, and it is possible to maintain the maintenance state of the high-temperature-pressure-resistant welding portion 14 for a long time, and the life of the pipe 12 can be extended. In addition, in this embodiment, although the 2nd heating of the 1st heating and the 2nd heating was shown, if the number of times of heating is plural, it is not limited to 2 times.

In addition, by performing the heating / cooling step of transforming a plurality of times in the regeneration point and the isothermal vacancy transformation step of continuing the transformation by holding the regeneration point at a predetermined temperature for a predetermined time, the regeneration point is formed by the pipe 12. It can be set as the organization with the ductility which is equal to a base material. In addition, when the voids, precipitates, or grain boundary segregation that are present along the grain boundaries of the structure are trapped in the mouth, the crack propagation rate is slowed down and the damage growth rate can be lowered. In addition, by extinguishing the coarse hardened structure, inhibition of fracture ductility is suppressed and good ductility can be obtained.

In addition, according to the regeneration device 11 of the deterioration unit C according to the present embodiment, since the main heater 25 and the sub heater 26 are provided, the main heater 25 and the sub heater 26 are provided. By temperature control, it can heat and cool, deteriorating the deterioration part C created in the high temperature-resistant pressure-resistant welding part 14, and its surroundings suitably, and can perform the optimal heat processing in the deterioration part C easily.

In the recrystallization heat treatment, 3 to 5 times are preferable as the repetition number of transformation of the regeneration point by the heating and cooling step.

In addition, in this embodiment, although the apparatus provided with two heaters of the main heater 25 and the sub heater 26 was demonstrated, for example, the quantity of heaters is not limited to two, if it is plural.

In addition, as the main heater 25 and the sub heater 26, not only a high frequency heating coil but various heaters which can control temperature can be used.

Example

The method described above is confirmed.

The pipe 12 is made of STAP24 material (2.25% Cr-1% Mo steel), and a pipe diameter of 355 mm and a thickness of 77 mm are used. In addition, the welding metal 13 also uses the same material as the piping 12. 7A is a micrograph of the HAZ portion 15 before the regeneration heat treatment, and the number density of the voids (deterioration portion C) is 930 pieces / mm 2.

The main heater 25 is separated from the surface of the pipe 12 and disposed 10 mm in the radial direction at a position facing the boundary between the pipe 12 and the weld metal 13. The sub heater 26 is disposed at a position 50 mm away from the boundary between the pipe 12 and the weld metal 13 in the circumferential direction of the pipe 12 and 10 mm in the radial direction.

And the main heater 25 rapidly heats the surface of the boundary member of the piping 12 of the high temperature-pressure-resistant welding part 14, and the welding metal 13 to temperature T1 = 1200 degreeC.

By the heating by the main heater 25, 300 seconds after the surface of the boundary member of the piping 12 of the high temperature-pressure-resistant welding part 14, and the welding metal 13 reached temperature T1 = 1200 degreeC, the main heater While heating by (25) is continued, heating by the sub heater 26 is started and the vicinity of the heating area | region HA1 by the main heater 25 is heated to temperature T1 = 1200 degreeC.

After the heating of the surrounding heating area HA2 by the sub heater 26 is continued for 1200 seconds, the heating temperature by the main heater 25 and the sub heater 26 is lowered in synchronization with a cooling rate of 50 ° C / hr. Let's do it.

Thereafter, the regeneration point is heated to 930 ° C by the main heater 25 and held for 60 minutes.

Next, the temperature control of the main heater 25 is carried out, the regeneration part is cooled to 700 degreeC, it hold | maintains for 300 minutes, and isothermal vacancy transformation process is performed.

Subsequently, the regeneration point is heated to 930 ° C by the main heater 25 and held for 60 minutes, and then the regeneration point is cooled to 500 ° C.

Further, the regeneration point is heated to 930 ° C by the main heater 25, and held for 60 minutes, and then the regeneration point is cooled to about 50 ° C / hr.

7B is a micrograph of the HAZ portion 15 after the regeneration heat treatment, and the number density of the voids (deterioration portion C) is 140 pieces / mm 2, and the void number density is 85% as compared with before the regeneration heat treatment. It was confirmed that it was decreasing. In addition, it was confirmed that the voids were located in the grain boundary before the regeneration heat treatment, and were trapped in the mouth after the regeneration heat treatment.

11: playback device
14: high temperature resistant welding part (metal member)
15: HAZ part (heat influence part)
25: main heater (first heater)
26: sub heater (second heater)
C: deterioration
HA1: heating zone (first heating zone)
HA2: heating zone (second heating zone)

Claims (10)

In the method of regenerating a deterioration part which arose in the metal member,
A first region in which a local region including the deterioration portion is heated to form a first heating region and press-contact the deterioration portion by compressive stress to the first heating region due to the restraint around the thermal expansion of the first heating region. Heating process,
A second heating step of forming a second heating area by heating the periphery of the first heating area after a predetermined time has elapsed from the start of heating by the first heating step while heating the first heating area. Characterized by
Regeneration method of deterioration part. The method of claim 1,
Characterized in that the first heating process and the second heating process are continued for a predetermined time.
Regeneration method of deterioration part. The method of claim 1,
The said metal member is equipped with a base material and the welding metal which connects the said base material,
The deterioration portion is present in the heat affected portion of the base material produced by welding,
The first heating zone is formed including the heat affected zone.
Regeneration method of deterioration part. The method of claim 3, wherein
Wherein the second heating zone is formed in the base material proximate the heat affected zone.
Regeneration method of deterioration part. The method of claim 1,
And a cooling step of synchronously cooling the first heating zone and the cooling of the second heating zone.
Regeneration method of deterioration part. The method of claim 5, wherein
After completion of the cooling step, recrystallization heat treatment is performed on the first and second heating regions.
Regeneration method of deterioration part. The method according to claim 6,
In the recrystallization heat treatment, a process of heating the metal member above its transformation point and cooling below the transformation point is repeated a plurality of times.
Regeneration method of deterioration part. The method according to claim 6,
In the process of performing the recrystallization heat treatment, isothermal vacancy transformation treatment is characterized in that
Regeneration method of deterioration part. In the apparatus for regenerating the deterioration portion generated in the metal member,
A first heater disposed at a position facing the deterioration portion and locally heating the deterioration portion;
And a second heater for heating the circumference of the heating area by the first heater.
Regeneration unit of deterioration part. The method of claim 9,
The heating by the first heater is preceded by the heating by the second heater.
Regeneration unit of deterioration part.

Images