JPH0578812A - Formation of film - Google Patents

Abstract

PURPOSE:To withstand corrosion by low-temp. sensitizing and to prevent the stress corrosion racking during an operation period by thermally spraying a highly corrosion resistant alloy at a low temp. on the surface of an Fe- and Ni-based alloy member and irradiating the resulted film with a laser, thereby reforming the film. CONSTITUTION:The highly corrosion resistant alloy consisting of the Fe- and Ni-base alloy is thermally sprayed by a low-temp. thermal spraying device 13 on the surface of a member 10 consisting of the Fe- and Ni-base alloy, such as structural members of an atomic power plant deteriorated with age to form the low-temp. thermally sprayed film 12. This film 12 is thermally sprayed with a laser by a laser irradiation device 15 to melt the surface part. This molten part is thereafter resolidified at 10<4> to 10<6> deg. C/S cooling rate. The surface reformed layer 14 consisting of a molten and solidified layer of a cell structure having the inter-cell spacing in a 0.2 to 2.0mum range is formed in this way. The structure in the atomic reactor, etc., are repaired in this way and the stress corrosion resistance cracking in weld heat affected zones is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of corrosion resistance of austenitic stainless steel, nickel base alloy, etc. in contact with corrosive environment, and particularly to improvement of stress corrosion cracking resistance of structural material welds of light water reactor plant in contact with high temperature and high pressure water. ..

[0002]

2. Description of the Related Art In an austenitic stainless steel welded portion such as a boundary portion of a light water reactor pressure vessel, grain boundary precipitation of Cr carbide occurs in the weld heat affected zone, and a phenomenon called sensitization occurs. In a corrosive environment in a furnace, it is said that the formation of a Cr-deficient layer in the vicinity of grain boundaries due to sensitization may cause stress corrosion cracking, and countermeasures for it are urgently needed.

In order to prevent such stress corrosion cracking of the welded portion, a method of desensitizing only the surface portion of the member related to corrosion by surface modification is adopted, and by irradiating with a high energy beam. A method has been devised for desensitization by heating the sensitized portion on the surface of the member to a temperature above the solution temperature. A laser beam is considered to be an important energy source because it can suppress the precipitation of carbides during the cooling process by a thermal cycle of rapid heating and rapid cooling and can be installed in the atmosphere.

Known examples include heating of the surface of the member to a temperature above the solution temperature as described in JP-A-60-165323, JP-A-61-52315 and JP-A-61-96025. JPA
There is a case where the surface is remelted as described in JP 61-177325. In each case, the carbide precipitated on the surface of the sensitizing member is dissolved to form a solid solution by heating, and the rapid cooling thereafter suppresses the precipitation of the carbide, thereby desensitizing the material. Further, in Japanese Patent Laid-Open No. 63-53210, ferrite having a grain size of 0.5 μm or less is stainless steel by quantitative control of irradiation energy within the composition range of stainless steel capable of forming fine ferrite on the surface. An example of improving the stress corrosion cracking resistance by forming it on the surface of steel is known.

Further, in recent years, as a new anticorrosion spraying system, an anticorrosion coating using an arc spray gun is being developed. For example, anticorrosion management, Vol. 35, N
o. 2, 1991, a method of spraying zinc, Al, and alloys thereof onto a steel sheet at a low temperature after applying a surface roughening agent is under study.

[0006]

The above-mentioned prior art does not consider measures against sensitization after surface modification, and has a problem in maintaining high corrosion resistance of the surface-modified material. For example, a light water reactor plant tends to have a long service life for its effective use, and an operating period of 30 to 40 years is assumed. Therefore, the parts that come into contact with high-temperature and high-pressure water at approximately 288 ° C in the plant will continue to be exposed at 288 ° C for over 40 years even after being subjected to the modification treatment for desensitization of the weld heat affected zone. It is necessary to give sufficient consideration to low temperature sensitization. In this respect, in the prior art shown in the above-mentioned known example, although the corrosion resistance immediately after the surface modification is significantly improved, the durability of the modified part under the low temperature sensitization environment as described above is not considered. The repair work of the actual nuclear plant is very time-consuming and expensive, and considering the repair work during the operation period, it is desirable that the number of repairs is small, that is, the durability of the reforming section against the low temperature sensitization is long. It is preferable from the viewpoint of cost.

Further, in the known example described in Japanese Patent Laid-Open No. 63-53210, ferrite is generated and the irradiation condition is determined from the ferrite grain size. Intergranular corrosion cracking occurs under the influence of low-temperature sensitization when the irradiation energy is high even within the range determined by known examples, and even if the austenite single phase is modified to a fine cell structure, low temperature It has been found that intergranular corrosion cracking does not occur even under sensitized conditions. "

Further, it has been found that a homogeneous anticorrosion coating can be formed by spraying a high corrosion resistant Fe, Ni alloy at a low temperature and then irradiating with a laser.

An object of the present invention is to provide a surface modification treatment method capable of withstanding corrosion due to low temperature sensitization after the modification treatment and preventing stress corrosion cracking during the operation period.

[0010]

In order to achieve the above object, a laser beam is applied to the surface of an austenitic Fe-Cr-Ni alloy so that the irradiation energy density is 0.0.
Controlled within the range of 05 J / μm to 0.05 J / μm, the cooling rate is within the range of 10 ⁴ ° C / s to 10 ⁶ ° C / s, and the cell spacing is within the range of 0.2 to 2.0 μm on the surface portion. The corrosion resistance of the alloy is improved by forming the cell structure in (1). In addition, austenitic Fe-Cr-N
A cell in which the surface portion of the i alloy is irradiated with a pulsed laser beam, the cooling rate is in the range of 10 ⁴ ° C / s to 10 ⁶ ° C / s, and the cell interval is in the range of 0.2 to 2.0 µm on the surface portion. By forming a structure, the corrosion resistance of the alloy is improved.

Furthermore, in order to perform appropriate preventive maintenance repairs on structural materials that have deteriorated over time, it is necessary to form a corrosion resistant film without adversely affecting existing structures. For this reason, new high corrosion resistance Fe, N
By spraying the i alloy at low temperature and then irradiating it with laser, the existing structure is not adversely affected by heat due to thermal spraying, and the surface of the low temperature irradiation film is flattened and gas components in the film are volatilized. By this, a homogeneous alloy film composition can be obtained.

[0012]

[Function] The intergranular corrosion behavior due to sensitization does not proceed immediately with the formation of precipitation nuclei of Cr carbide, but when the Cr concentration near the grain boundaries decreases to below a certain amount as the precipitation nuclei grow, Intercalation occurs. When the surface is melted by the irradiation of the laser beam, an overlapping portion of the molten bead is generated in the modified layer. When the beads are overlapped and irradiated, due to the thermal effect of the adjacent beads, a portion held in the Cr carbide precipitation temperature region inevitably exists during the heating-cooling thermal cycle. When the irradiation energy of the beam is high, the cooling rate is low, so that the time for holding at the above-mentioned precipitation temperature becomes long, and the precipitation nuclei of Cr carbide are formed, and the frequency thereof is high. After reforming, the nucleated carbides grow under the temperature conditions that bring about low-temperature sensitization, and as described above, C
Since the r-deficient layer is formed, the modified layer is re-sensitized. Therefore, when the irradiation energy is large, even if the corrosion resistance immediately after the modification is good, the intergranular corrosion progresses due to the subsequent low temperature sensitization. In addition, if the irradiation energy is too low, the penetration will be poor and a sufficient desensitization layer cannot be obtained. In addition, the solidification structure of stainless steel changes depending on the difference in cooling rate. Considering the influence of the solidification structure on the precipitation nucleation of Cr carbides, in the structure where ferrite is present, the primary crystal is caused by the macroscopic non-uniformity of Cr concentration due to the presence of ferrite and the difference in the diffusion behavior of Cr between ferrite and austenite. It is considered that the ferrite / austenite two-phase structure has more precipitation nucleation sites than the primary austenite single-phase structure, and is likely to form nucleation.

The inventors have an irradiation energy density of 0.00
When controlled within the range of 5 J / μm to 0.05 J / μm, a cell structure having a cooling rate of 10 ⁴ ° C./s to 10 ⁶ ° C./s and a cell spacing of 0.2 to 2.0 μm is obtained. Has a surface part formed. In that case, it was found that, because the above-mentioned carbide precipitation temperature holding time was short, precipitation nuclei were not formed or the frequency was low, and intergranular corrosion did not occur even under low-temperature sensitization conditions. In addition, the irradiation with the pulsed beam completes the solidification by forming the beam spot, and the cooling rate is 10 ⁵ ° C.
It has been found that there is almost no heat-affected zone in the relevant area because the heat-affected zone is extremely fast at / s to 10 ⁶ ° C / s and the thermal effect of the adjacent spot is small. Furthermore, without moving the laser torch linearly, the beam spots were discontinuously formed in the modified region, and finally all the spots were partially overlapped to form a surface-modified layer having no gap. In this case, it was found that the influence of the adjacent spots described above was further reduced.

Further, a new high corrosion resistance Fe / Ni alloy, that is, P / N of a low carbon system in which precipitation of Cr carbide is small.
At a temperature lower than the operating temperature of the plant, for example, 288 ° C., such as stainless steel whose content is reduced to 0.01% or less, or Inconel 600 containing 1-3% niobium.
In the following, the low-temperature spray coating is subjected to low-temperature spraying, without adversely affecting the existing structure by the heat of spraying, and thereafter, by laser irradiation, the surface of the low-temperature spray coating is rapidly heated and flattened by cooling. It was also found that a homogeneous alloy coating composition can be obtained by volatilizing the gas component in the coating.

[0015]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows an example in which a typical austenitic stainless steel, SUS304 stainless steel, is applied to a part of the internal structure of a light water reactor plant when the irradiation energy is changed. Irradiation energy density is 0.005J /
Under conditions of μm or less, poor penetration or solidification cracking occurred. Each of the test pieces was simulated by accelerating the low-temperature sensitization condition of 288 ° C for 40 years, which is the operating period of the light water reactor plant.
Boiled H ₂ SO ₄ -CuS with heat history of 00 ° C, 24h
After being dipped in the O ₄ solution for 72 h, it was bent to 50 R and the state of cracking was observed. As a comparative material, the intergranular corrosion test was carried out in the state of being modified without giving a thermal history of low temperature sensitization (LTS). No intergranular cracks were observed on the surface of the as-modified surface without applying the LTS conditions, whereas LT
Irradiation energy density is 0.0 in the reformed part under S condition.
Irradiation conditions controlled within the range of 05 J / μm to 0.05 J / μm, that is, cooling rate of 10 ⁴ ° C / s to 10 ⁶ ° C / s
And the cell spacing is in the range of 0.2 to 2.0 μm, only under the condition that the cell structure is formed, solidification crack does not occur, and the surface modified layer that can withstand the low temperature sensitization condition is formed. It Therefore, as an appropriate irradiation condition for surface modification, the irradiation energy density is 0.005 J / μm to 0.05 J / μm.
It is necessary to control within the range of.

(Embodiment 2) FIG. 2 is a sectional view of a low temperature spray coating. This is a cross section of a coating sprayed on a member by melting a high corrosion resistant alloy by an arc, and is an example in which a rough surface forming agent is applied in order to enhance the adhesion of the sprayed coating. The rough surface forming agent is an example in which a commercially available coating type rough surface forming agent, which is a two-liquid solvent type sprayed room temperature dry type and contains ceramics fine powder and a special epoxy resin as main components. In the case of low temperature thermal spraying of stainless steel, if the fine ceramic powder or special epoxy resin remains undesirably, high corrosion resistance Fe, Ni
A roughening agent containing a base alloy powder and a special adhesive is used. In the film thus formed, bubbles are generated and the surface of the film is roughened, but it can be used as it is in normal use.

(Embodiment 3) FIG. 3 schematically shows a method of forming a surface-modified portion formed by low-temperature spraying a highly corrosion-resistant Fe-Ni-based alloy and then irradiating a pulsed laser. On the surface of the existing in-core structure 10, a high corrosion resistance Fe, Ni-based alloy is supplied from the low temperature spray nozzle 13 to a cooling air flow, air or, preferably, an inert gas such as argon,
The low temperature sprayed coating 12 is formed by spraying the surface of the member together with nitrogen and helium. After that, the surface of the low temperature sprayed coating 12 is rapidly heated and cooled by laser irradiation 15 to form the laser surface modified portion 14. When the surface modifier thus formed was subjected to an intergranular corrosion test similar to that of Example 1, no intergranular cracks were observed even in the modified part subjected to the LTS condition, and the surface modifier endured the low temperature sensitization condition. It was found that a surface-modifying layer was formed.

(Embodiment 4) FIG. 4 shows a powdery tape 16 with a powdery alloy element, which is a component capable of forming an austenite single-phase cell structure, and is added to the powdery tape 16.
7 shows a state when the member 10 is brought into close contact with the member 10 and then a laser beam is irradiated to form the alloy phase structure on the surface portion. As the alloy component, JIS standard SUS3
04, 316, 304L, 316L, 348, NCF60
0, NCF800, NCF690, etc. are suitable. Furthermore, among these, it is desirable to limit P and N as impurity elements that cause segregation during solidification to at least 0.01% or less. An intergranular corrosion cracking test was performed under the conditions at this time. The base material is SUS312 stainless steel, which is an austenite / ferrite dual phase alloy, and SUS30, which is also an austenite / ferrite dual phase alloy.
8 stainless steel, austenite single phase Inconel 600, also austenite single phase SUS316
Stainless steel was used. In both alloys, the solidification structure remains in an austenite / ferrite two-phase state only by melting and rapid solidification by laser irradiation, and there are many Cr carbide nucleation sites, and it is difficult to suppress low-temperature sensitization. Also, Inconel 600, S used as a structural material in the furnace
Since US316 stainless steel has a low solid solubility of carbon, desorption sensitization can be achieved only by melt-quenching and solidification by laser irradiation. Under irradiation conditions, the residual stress is concentrated due to an extremely fast solidification rate and cracking can be suppressed. Have difficulty. 0.12
29Cr-9Ni SUS308 stainless steel with C content of wt%, 20Cr-1 with C content of 0.12wt%
0Ni SUS308 stainless steel, 74Ni-16Cr Inconel 600 with C content of 0.07wt%,
20Cr-12Ni SU with 0.07 wt% C content
After solutionizing both S316 stainless steel at 1250 ° C, 6
Sensitization heat treatment at 00 ℃, 0.5h
The surface portion irradiated with the laser beam from the top of the tail coated with the powder at the ratio of 8Cr-8Ni-74Fe was used as the test material for the intergranular corrosion cracking test. Each test piece was subjected to a thermal history of 500 ° C. for 24 hours, which was simulated by accelerating the low temperature sensitization condition, immersed in a boiling H ₂ SO ₄ —CuSO ₄ solution for 72 hours, and then bent at 50 R to see the cracks. .. still,
As a comparative material, a base material not surface-modified was subjected to the low temperature sensitization heat history and subjected to the above-mentioned intergranular corrosion test. As a result, intergranular cracks occurred in all the base materials, whereas no intergranular cracks were seen in the modified material. According to these new findings, the cell spacing on the surface portion is in the range of 0.2 to 2.0 μm by irradiation of the laser beam under the proper condition that the cooling rate is in the range of 10 ⁴ ° C / s to 10 ⁶ ° C / s. It was found that when a cell structure is formed, the intergranular corrosion cracking resistance is improved even in different materials.

(Embodiment 5) FIG. 5 is a diagram showing a main part of a low temperature thermal spraying apparatus. The highly corrosion resistant alloy is made into a linear shape 20 and supplied by an automatic supply device. Each of the at least two wires 20 is connected to a conductive terminal 19 connected to a power source 21, and an arc 24 is generated at the end of the nozzle 18. The alloy melted in the arc portion causes the compressed gas 22 accumulated in the cylinder 23 to form a conical airflow so as to enclose the arc portion 24. In the arc portion 24, the molten lower alloy is attracted by the negative pressure of the blowing air current 25 to form droplets 26,
It is sprayed on the surface of the target member together with the spray airflow 25.

As a result of examining various gases as the compressed gas, the present inventors have found that the inert gas can prevent the oxidation of the sprayed coating more than the air. Argon is most preferable as the inert gas, and helium and nitrogen are preferable as the next. In addition, in order to apply the present invention to a narrow portion such as the inside of a reactor pressure vessel, it is desirable that the flight distance of a droplet is short. For this reason, the present inventors grasped the relationship between the optimum arc current and the blowing air flow rate and the relationship between the member surface temperature by various experiments, and determined these control factors by the automatic detection device and the current and air flow rate. The control device enables automatic monitoring so that the surface of the member does not exceed the target value. For example, by setting the temperature in the furnace so that it does not exceed 288 ° C., it is possible to prevent the target member SUS304 from becoming sensitized. Further, liquid helium or nitrogen can be used to enhance the cooling effect of lowering the temperature and to reduce the amount of gas used.

(Sixth Embodiment) FIG. 6 is an example in which the present invention is further applied. In the case of a wide range of target members, we have developed a multi-type nozzle that can combine multiple nozzles to form a droplet-shaped range in order to increase the efficiency of low-temperature spraying. Also in this case, the automatic monitoring system shown in the sixth embodiment can be applied.
That is, by grasping the relationship between the optimum arc current and the blowing air flow rate and the relationship between the member surface temperature, these control factors are detected by the automatic detection device and the current and air flow rate control device.
It is now possible to monitor automatically so that the surface of the member does not exceed the target value. For example, by setting the temperature in the furnace so that it does not exceed 288 ° C., it is possible to prevent the target member SUS304 from becoming sensitized. Furthermore, liquid helium or nitrogen can be used at a low temperature to reduce the amount of gas used.

(Embodiment 7) FIG. 7 shows an example in which the present invention is applied to a narrow portion of a reactor internal structure of a shroud 30 which is an internal structure of a light water reactor pressure vessel 27. The shroud is a structure that supports the fuel assembly, and like the core support plate 29,
Made of stainless steel. It should be noted that the present invention is naturally applicable to the reactor internal structure made of stainless steel or nickel-based alloy other than the shroud. Further, the shroud support leg 31 and the shroud support plate 32 are made of a nickel base alloy. In particular, the shroud 30 is irradiated with neutrons, and the characteristics of the material change due to long-term operation. In order to extend the service life of the plant, the reliability of the structure can be further improved by forming a high corrosion resistant alloy film on these existing structures in advance, if necessary. This embodiment is an example in which the low temperature spraying and laser irradiation of the present invention are applied to an operating plant. Since the reactor internal structure has a high radiation equivalent rate, the water seal 39 stores water for shielding at the upper portion and shields the water.
In addition, it is possible to work in the drained state around the shroud. The low temperature spraying and laser irradiation device is attached to the head 35, and by means of the opening / closing bar 34 and the opening / closing pin 36, the pole 3
It is fixed at 3. 42 is a drive mechanism, and the hose 46,
A cable 45 is a low temperature spraying apparatus control unit and a gas cylinder 44. A gas supply pipe 38 and a hole 27 are provided to control the atmosphere around the shroud.

According to this embodiment, after the structural material of the existing plant is modified, it is possible to prevent stress corrosion cracking under the low temperature sensitization condition corresponding to the operating temperature.
It has a great effect on prolonging the life of the light water reactor plant that comes into contact with the high temperature and high pressure water.

[0024]

According to the present invention, after the structural material of the existing plant is modified, stress corrosion cracking under the low temperature sensitization condition corresponding to the operating temperature can be prevented.
It has a great effect on prolonging the life of the light water reactor plant that comes into contact with the high temperature and high pressure water. Further, it is possible to prevent stress corrosion cracking during the 40-year operation period of the above-mentioned plant which is currently assumed, so that there is an effect of greatly reducing the construction cost.

[Brief description of drawings]

FIG. 1 is a schematic view of a surface modified portion formed by irradiation with a pulse laser.

FIG. 2 is a sectional view of an anticorrosion coating formed by low temperature spraying.

FIG. 3 is a schematic view of an anticorrosion coating formed by irradiating a member at low temperature and then irradiating with laser.

FIG. 4 is a diagram illustrating a process of bringing a highly corrosion resistant alloy powder tape into close contact and irradiating with a laser beam to form an anticorrosion coating.

FIG. 5 is a diagram schematically showing a low temperature spraying apparatus.

FIG. 6 is a diagram schematically showing an apparatus for forming a high corrosion resistant coating on a member by using a plurality of low temperature spray nozzles.

FIG. 7 is a diagram showing an example in which low temperature spraying and laser irradiation of the present invention are applied to a shroud for the internal structure of a furnace.

FIG. 8 is a diagram illustrating an example in which low temperature spraying and laser irradiation of the present invention are applied to a shroud.

[Explanation of symbols]

1 ... Base material, 2 ... Welding part, 3 ... Laser beam, 4 ... Laser processing head, 5, 7, 8 ... Bending mirror, 6 ...
Beam guide tube, 7 ... Water seal cylinder, 8 ... Stopper, 9 ...
Laser oscillator, 10 ... Member, 11 ... Rough surface forming material, 12 ...
Low temperature sprayed coating, 13 ... Low temperature spraying device, 14 ... Laser surface modification part, 15 ... Laser irradiation device, 16 ... Tape with powder,
17 ... Powder pressing tape pressing device, 18 ... Nozzle, 19
... Conductive terminals, 20 ... Wires, 21 ... Power source, 22 ... Compressed gas, 23 ... Cylinder, 24 ... Arc, 25 ... Spraying airflow, 26 ... Droplets, 27 ... Reactor pressure vessel, 28 ... Upper lattice plate, 29 ... Core support plate, 30 ... Shroud, 31 ... Shroud support leg, 32 ... Shroud support plate, 33 ... Pole, 34 ... Opening bar, 35 ... Head, 3
6 ... Open / close pin, 37 ... Gas supply hole, 38 ... Gas supply pipe, 39 ... Water seal, 40 ... Water supply sparger, 41 ... Core spray pipe, 42 ... Drive mechanism, 43 ... Low temperature spray control device, 44 ... Gas cylinder, 45 … Cables, 46… hoses.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasukata Tamai 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Koichi Kurosawa 3-cho, Hitachi-shi, Ibaraki No. 1 No. 1 Hitachi Ltd., Hitachi Plant (72) Inventor Kinya Aota 4026 Kujicho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd.

Claims (10)

[Claims] 1. A method for forming a film, which comprises spraying a highly corrosion-resistant alloy at a low temperature on the surface of a member made of an Fe, Ni-based alloy, and then irradiating a laser. 2. A high corrosion resistant alloy made of Fe, Ni-based alloy is sprayed at a low temperature on the surface of a nuclear power plant member made of Fe, Ni-based alloy, and then laser light is irradiated to melt the surface portion. It has a surface-modified layer consisting of a melt-solidified layer having a cell structure in which the cell spacing is in the range of 0.2 to 2.0 μm by resolidification having a cooling rate of 10 ⁴ ° C / s to 10 ⁶ ° C / s. A film forming method characterized by. 3. A nuclear reactor internal structure repaired by a film forming method characterized in that a high corrosion resistant alloy is sprayed at low temperature on the surface of a member made of Fe, Ni-based alloy, and then laser irradiation is carried out. 4. A method for forming a coating film, comprising: forming a tape of highly corrosion-resistant alloy powder on a surface of a member made of an Fe, Ni-based alloy, bringing the powder into close contact with the surface of the member, and then irradiating laser. 5. A coating forming method comprising spraying a high corrosion resistant alloy at low temperature on a surface of a member made of Fe, Ni-based alloy and then irradiating with laser. .. 6. An apparatus characterized in that a high-corrosion-resistant alloy is sprayed at low temperature on the surface of a member made of Fe, Ni-based alloy, and then laser irradiation is carried out to form a film. 7. A device for spraying a high corrosion resistant alloy at a low temperature onto a surface of a member made of an Fe, Ni-based alloy, and then irradiating a laser to form a film, as a blowing cooling air flow,
A device characterized by using an inert gas. 8. An apparatus for spraying a highly corrosion resistant alloy at a low temperature on a surface of a member made of an Fe, Ni-based alloy and then irradiating a laser to form a film, as an air flow for spray cooling,
An apparatus characterized by using liquid nitrogen. 9. In a device for spraying a high corrosion resistant alloy at a low temperature onto a surface of a member made of an Fe, Ni-based alloy and then irradiating a laser to form a film, liquid argon is used as a blowing cooling air flow of the low temperature spraying device. A device characterized by the above. 10. In an apparatus for spraying a high corrosion resistant alloy at low temperature on a surface of a member made of Fe, Ni-based alloy, and then performing laser irradiation to form a film, the temperature of the surface of the member of the blowing cooling air flow of the low temperature spraying device is controlled. A device that has a circuit that controls the flow rate of the blowing cooling airflow to detect and set the temperature.