JP2015155110A - Laser build-up weld device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide laser build-up weld device and method capable of suppressing weld crack, such as solidification crack and liquifaction crack when performing build-up weld by using a laser.

SOLUTION: A laser build-up weld device 10 of an embodiment comprises: an optical path part for radiating laser beam emitted from a laser oscillator 29 as laser beam 28 to a build-up object 40 formed of an Ni-based superalloy; an energy profile conversion part 30 disposed on the optical path part, and forming the laser beam 28 having a top hat shaped energy profile; and a filler material supply part for supplying powders of filler material to the laser beam radiation part of the build-up object 40.

COPYRIGHT: (C)2015,JPO&INPIT

Description

  Embodiments described herein relate generally to a laser overlay welding apparatus and a laser overlay welding method.

  In a gas turbine, thermal efficiency can be improved by raising the combustion temperature. Therefore, in the 1990s, the mainstream of the stationary blade inlet gas temperature was 1100 ° C., but since the 2000s, models of 1300 ° C. and 1500 ° C. have been developed.

  A tip squealer for a moving blade of a gas turbine is provided at the tip of the moving blade, and suppresses a decrease in efficiency due to leakage of combustion gas from the tip of the blade. In addition to being exposed to hot combustion gases, the tip squealer may come into contact with opposing shroud segments. Therefore, it is easily damaged by high temperature oxidation and erosion.

When the tip squealer is worn in this way, repair by laser overlay welding is performed. A Ni-base superalloy used as a moving blade material for a gas turbine is a precipitation-strengthened Ni-base superalloy strengthened by precipitation of a Ni ₃ Al phase called a γ ′ phase in a Ni matrix. When overlay welding is performed on the precipitation-strengthened Ni-base superalloy using the same material, it is difficult to obtain excellent weldability.

  The weldability in the precipitation-strengthened Ni-base superalloy is qualitatively arranged by the contents of Al and Ti. When the concentrations of Al and Ti are high, the weldability is poor, and welding cracks such as solidification cracks, liquefaction cracks, and ductility deterioration cracks are caused during welding. For example, single crystal superalloys such as GTD-111 (manufactured by General Electric, USA) and ReneN5 (manufactured by General Electric, USA) that are currently used as the first stage blades of gas turbines are classified as difficult-to-weld materials. Therefore, it is considered that weld cracks are likely to occur.

  These weld cracks are suppressed by reducing the welding residual strain introduced during welding. For this reason, laser overlay welding with low welding heat input is adopted mainly for aircraft gas turbines.

  FIG. 7 is a view showing a cross section perpendicular to the irradiation direction of a laser beam used in conventional laser overlay welding. FIG. 8 is a diagram schematically showing the energy profile of the laser beam in the XX section of FIG. FIG. 9 is a diagram schematically showing an integrated energy distribution during the passage of the laser beam of the XX cross section in FIG.

  As shown in FIG. 7, the cross section of the laser beam used in conventional laser overlay welding is circular. As shown in FIG. 8, this laser beam has an energy profile called a Gaussian type. When such a Gaussian type laser beam is used, as shown in FIG. 9, the distribution of accumulated energy (heat input) is high in the central portion and low in the peripheral portion.

Journal of the Gas Turbine Society of Japan Vol.40, No.4, p.130

  As described above, in a Gaussian laser beam used for conventional laser overlay welding, heat input is high at the center and low at the periphery. Therefore, when heat input is set according to the peripheral part, the heat input at the center part becomes excessive, and solidification cracking or liquefaction cracking may occur.

  The problem to be solved by the present invention is to provide a laser overlay welding apparatus and a laser overlay welding method capable of suppressing weld cracking such as solidification cracking and liquefaction cracking when overlay welding is performed using a laser. It is.

  The laser build-up welding apparatus of the embodiment is provided with an optical path unit for irradiating a build-up target made of a Ni-based superalloy with a laser beam emitted from a laser oscillator as a laser beam, and a top hat type. An energy profile conversion unit that constitutes the laser beam having the energy profile, and a filler material supply unit that supplies powder of the filler material to the laser beam irradiation unit of the build-up object.

It is the figure which showed typically the structure of the laser overlay welding apparatus of embodiment. It is the figure which showed the cross section perpendicular | vertical to the irradiation direction of the laser beam currently used for the laser overlay welding of embodiment. It is the figure which showed typically the energy profile of the laser beam in the AA cross section of FIG. It is the figure which showed the cross section of the laser beam perpendicular | vertical to the irradiation direction in order to demonstrate the energy profile of the laser beam currently used for the laser overlay welding of embodiment. It is the figure which showed typically the accumulated energy distribution during the laser beam of the AA cross section of FIG. It is the figure which showed typically the side of the build-up part in order to demonstrate the length of the weld crack of the whole surface of the build-up part. It is the figure which showed the cross section perpendicular | vertical to the irradiation direction of the laser beam used for the conventional laser overlay welding. It is the figure which showed typically the energy profile of the laser beam in the XX cross section of FIG. It is the figure which showed typically the accumulated energy distribution during the laser beam of the XX cross section of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram schematically illustrating a configuration of a laser overlay welding apparatus 10 according to an embodiment. As shown in FIG. 1, the laser overlay welding apparatus 10 includes a laser oscillator 29, a welding laser head 20, and an optical fiber 21 that guides laser light generated by the laser oscillator 29 to the welding laser head 20.

  The laser overlay welding apparatus 10 includes a powder supply device 22 that supplies a powder 23 of the filler material, and a powder supply tube that guides the powder 23 of the filler material derived from the powder supply device 22 to the welding laser head 20. 24. Further, the laser overlay welding apparatus 10 includes a gas supply device 26 that supplies the shield gas 25 and a gas supply pipe 27 that guides the shield gas 25 from the gas supply device 26 to the welding laser head 20.

  As the laser oscillator 29, for example, a semiconductor laser, a YAG laser, a fiber laser, a disk laser, or the like can be used. The laser light emitted from the laser oscillator 29 has, for example, a Gaussian type energy profile.

  The welding laser head 20 is attached so as to be able to scan in the build-up direction, for example. In addition, you may comprise so that the build-up target 40 side may be scanned. In the welding laser head 20, for example, an optical path 20 b that irradiates the build-up object 40 with laser light from a laser oscillator 29 as a laser beam 28, and a filler material powder 23 from the powder supply device 22 are built-up object. A powder passage 20c for supplying the gas to 40 and a gas passage 20d for supplying the shielding gas 25 from the gas supply device 26 to the build-up object 40 are provided.

  The laser beam 28, the powder 23, and the shield gas 25 are irradiated or supplied to the build-up object 40 from the end surface 20 a of the welding laser head 20 facing the build-up object 40, for example. In the end face 20a, the ejection holes for ejecting the powder 23 and the ejection holes for ejecting the shield gas 25 are, for example, uniformly formed in the circumferential direction around the emission holes from which the laser beam 28 is emitted. Moreover, the ejection hole which ejects the powder 23 is formed inside the ejection hole which ejects the shield gas 25, for example.

  For example, the optical path 20b in the welding laser head 20 is provided with an energy profile conversion unit 30 in which the energy profile of the laser beam 28 emitted from the welding laser head 20 is a top hat type. The energy profile conversion unit 30 will be described in detail later.

  Here, the optical path 21b in the optical fiber 21 and the welding laser head 20 functions as an optical path portion. The powder supply device 22, the powder supply pipe 24, and the powder passage 20c in the welding laser head 20 function as a filler material supply unit. The gas supply device 26, the gas supply pipe 27, and the gas passage 20d in the welding laser head 20 function as a seal gas supply unit.

  Here, an example is shown in which a system for supplying the shield gas 25 is provided in order to suppress oxidation of the built-up portion 50 and the like, but a system for supplying the shield gas 25 may not be provided.

The build-up object 40 on which build-up welding is performed is made of, for example, a precipitation-strengthened Ni-base superalloy obtained by precipitation strengthening Ni ₃ Al (γ ′ phase). It is difficult from the viewpoint of weldability to build-up weld the same precipitation-strengthening Ni-base superalloy with the same material. Therefore, as the filler material, it is preferable to use solid solution strengthened Ni-base superalloy powder among the Ni-base superalloys.

  Examples of the solid solution strengthened Ni-base superalloy include a Ni-base superalloy having lattice strain such as Co, Cr, Mo, and W whose main strengthening factor is a solid solution in Ni. Although it does not specifically limit as a solid solution strengthening type Ni base superalloy, Specifically, for example, IN625 (made by Special Metal), IN617 (made by Special Metal), HA230 (made by Haynes Alloy), etc. Is mentioned.

  Here, in a solid solution strengthened Ni-base superalloy, components such as Nb, Si, and Hf may lower the local melting point. Although the effects of the present embodiment can be obtained even if a solid solution strengthened Ni-base superalloy containing these components is used, a solid solution strengthened Ni-base superalloy that does not contain these components is used. May be.

  The average particle diameter of the filler powder 23 is preferably 45 μm to 110 μm, for example, so as to be supplied to the molten pool 51 and melted reliably. The average particle diameter is a median diameter, and is measured by, for example, a laser diffraction scattering method.

  The shield gas 25 is composed of, for example, an inert gas. As this inert gas, helium, argon, nitrogen etc. can be used, for example.

  Next, the pattern of the laser beam 28 will be described.

  FIG. 2 is a view showing a cross section perpendicular to the irradiation direction of the laser beam 28 used for laser overlay welding according to the embodiment. FIG. 3 is a diagram schematically showing the energy profile of the laser beam 28 in the AA cross section of FIG. FIG. 4 is a view showing a cross section of the laser beam 28 perpendicular to the irradiation direction in order to explain the energy profile of the laser beam 28 used in the laser overlay welding of the embodiment. FIG. 5 is a diagram schematically showing an integrated energy distribution during the passage of the laser beam 28 of the AA cross section of FIG.

  The shape of the laser beam 28 used for laser overlay welding in the embodiment in a cross section perpendicular to the irradiation direction (hereinafter referred to as a laser beam cross section) is, for example, a substantially square shape as shown in FIG. In this case, the shape of the laser spot is substantially square.

  Here, in addition to the rectangle and the square, the substantially square includes a configuration in which four corners are R portions as shown in FIG. Further, the substantially quadrangular shape includes a configuration in which four corners are cut in a straight line shape, for example, C chamfering.

  Note that, from the viewpoint of making the integrated energy distribution uniform during the passage of the laser beam 28, the shape of the laser beam cross section is preferably substantially rectangular, but the laser beam cross section may be circular, for example. . In this case, the shape of the laser spot is circular.

  As shown in FIG. 3, the laser beam 28 has an energy profile called a top hat type. As the top hat type energy profile, as shown in FIG. 3, it is preferable that the energy is uniform over the cross section of the laser beam. The top-hat type energy profile here includes the following cases in addition to the case where the energy is uniform over the laser beam cross section.

  In the laser beam cross section shown in FIG. 4, the energy of the laser beam 28 is accumulated outward with the cross-sectional center as the center O, and an area inside the boundary 60 that is 87% of the total energy of the laser beam 28 in the cross section is an area 61. And On the boundary 60, the distance from the center O is equal, and the shape of the boundary 60 is circular. In the region 61, the minimum value of energy is 80% or more of the maximum value of energy. That is, in the region 61, when the maximum energy value is 1, the minimum energy value is 0.8 or more. A laser beam cross section having such an energy profile is also included in the top hat type energy profile.

  Here, the energy amount in the beam waist of the Gaussian beam is about 87% of the energy amount in the entire cross section, and accordingly, the boundary 60 in the top hat type is set to 87 of the total energy as described above. % Position. In addition, the reason why the minimum energy value is 80% or more of the maximum energy value is that, within this range, substantially uniform heat input is obtained and weld cracking is suppressed.

  Here, the boundary 60 which is 87% of the total energy of the laser beam 28 in the cross section is determined by measuring the energy distribution of the laser beam using, for example, a Primes focus monitor. Also, the maximum value and the minimum value of the energy within the boundary 60 are determined by measuring the energy distribution of the laser beam using, for example, a Primes focus monitor.

  When the laser beam 28 having such a top hat type energy profile is used, as shown in FIG. 5, the distribution of accumulated energy (heat input) is uniform in the central portion and the peripheral portion. Thereby, since the heat input supplied to the build-up surface 41 becomes uniform, the occurrence of solidification cracking and liquefaction cracking can be suppressed.

  Here, an energy profile conversion unit 30 that converts a laser beam having a Gaussian type energy profile into a laser beam 28 having a top hat type energy profile will be described.

  The energy profile conversion unit 30 is configured by, for example, a beam homogenizer that makes the energy profile uniform. A laser beam having a Gaussian type energy profile passes through this beam homogenizer to become a laser beam having a top hat type energy profile. This beam homogenizer is provided, for example, in the optical path 20b through which the laser light in the welding laser head 20 passes. A beam homogenizer may be interposed in the optical fiber 21.

  In addition, the energy profile conversion unit 30 may be configured with, for example, a rectangular core fiber. In this case, for example, the optical path 20b may be composed of a rectangular core fiber. Moreover, you may comprise the optical fiber 21 with a square core fiber. A laser beam having a Gaussian type energy profile passes through the rectangular core fiber, so that a laser beam having a top hat type energy profile is obtained.

  Note that the method of making the energy profile of the laser beam 28 the top hat type is not limited to the above-described method, and any method can be used as long as the top hat type energy profile defined above can be obtained.

  Next, the laser overlay welding method according to the embodiment will be described with reference to FIG.

  The laser beam emitted from the laser oscillator 29 is guided to the optical path 20 b of the welding laser head 20 through the optical fiber 21. The laser beam guided to the optical path 20 b is converted into a top hat type energy profile by the energy profile conversion unit 30.

  The laser beam converted into the top hat type energy profile is emitted from the center of the end face 20 a of the welding laser head 20 toward the build-up surface 41 of the build-up object 40 as a laser beam 28. Then, the emitted laser beam 28 is applied to the build-up surface 41 of the build-up object 40. In addition, when forming the build-up part 50 by laminating | stacking in multiple stages, the to-be-laid surface 41 becomes the already-formed build-up part 50.

  The filler material powder 23 supplied from the powder supply device 22 via the powder supply pipe 24 is supplied from the welding laser head 20 toward the build-up surface 41. For example, as shown in FIG. 1, the powder 23 is supplied along the laser beam 28 from the periphery of the laser beam 28.

  The powder 23 supplied to the build-up surface 41 is melted by the energy of the laser beam 28 to form a molten pool 51. At this time, since the energy profile of the laser beam 28 is a top hat type, the heat input is uniformly supplied to the build-up surface 41. The powder 23 is melted in the molten pool 51 by the energy of the laser beam 28 and then solidified to form the built-up portion 50.

  The shield gas 25 supplied from the gas supply device 26 via the gas supply pipe 27 is blown out from the welding laser head 20 toward the overlay surface 41 and the molten pool 51. Thereby, the molten pool 51 and its peripheral part are covered with the shield gas 25 and are cut off from the atmosphere. Therefore, when overlaying, the overlaying part 50 close to the molten powder 23 and the molten pool 51 is suppressed from being oxidized by the atmosphere. In addition, the shielding gas 25 may be blown out to the build-up surface 41 side so that the circumference | surroundings of the powder 23 supplied along the center laser beam 28 and the laser beam 28 may be covered, for example.

  As described above, in the build-up process, the filler material powder 23 is supplied to the build-up surface 41, the laser beam 28 is irradiated, and the build-up portion 50 is applied to the build-up surface 41 by the melted powder 23. Is formed.

  In addition, in the build-up process, for example, when a new build-up part 50 is formed on the already formed build-up part 50 to form a multi-layer build-up part 50, a new build-up part is formed. 50 is preferably laminated in a state in which the temperature (surface temperature) of the built-up portion 50 already formed is 400 ° C. or higher. By forming a new build-up part 50 on the build-up part 50 having a temperature of 400 ° C. or higher, weld cracking can be suppressed. In addition, the temperature of the build-up part 50 is measured using a thermocouple, a radiation thermometer, etc., for example.

  In the above description, an example is shown in which the filler powder 23 is supplied toward the build-up surface 41 via the welding laser head 20, but the present invention is not limited to this configuration. For example, the powder 23 of the filler material may be supplied to the build-up surface 41 from, for example, a separately provided supply pipe without using the welding laser head 20.

  According to the laser build-up welding apparatus and the laser build-up welding method of the above-described embodiment, heat input is uniformly supplied to the build-up surface 41 by using the laser beam 28 having a top hat type energy profile. Is done. Thereby, weld cracks such as solidification cracks and liquefaction cracks can be suppressed.

  The laser build-up welding apparatus and laser build-up welding method of the embodiment can be used as a laser build-up welding method for repairing wear and cracks of gas turbine high-temperature parts such as moving blades and stationary blades, for example. It is. Further, the present invention can be widely applied not only to gas turbine parts but also to laser overlay welding for a parent phase made of a Ni-base superalloy. Furthermore, even when the parent phase is made of a metal other than the Ni-base superalloy, the laser overlay welding apparatus and the laser overlay welding method of the embodiment can be applied. Also in these cases, heat input is uniformly supplied to the surface to be built, and weld cracks such as solidification cracks and liquefaction cracks can be suppressed.

(Evaluation of weld cracks)
Next, it will be described that welding cracks can be suppressed by forming the built-up portion 50 by the laser build-up welding apparatus and the laser build-up welding method of the embodiment.

Example 1
In Example 1, overlay welding was performed using the laser overlay welding apparatus 10 shown in FIG. The laser overlay welding apparatus 10 shown in FIG. 1 was also used in the following examples and comparative examples.

  As the build-up object 40, a block material of MM247LC, which is a Ni-based superalloy, was used. The size of the build-up object 40 was 50 mm in length, 10 mm in width, and 20 mm in thickness. The build-up surface 41 was a surface composed of the above-described length (50 mm) and width (10 mm).

  HA230 was used as a filler material. The average particle size (median diameter) of the filler powder 23 was 90 μm. The average particle size was measured by a laser diffraction scattering method (hereinafter the same).

  Here, in Table 1, the chemical composition of the material which comprises the build-up target object 40 and a filler material is shown.

  A semiconductor laser was used as the laser oscillator 29. A laser beam 28 having a circular laser beam cross section was used. Therefore, the shape of the laser spot was circular. The energy profile of the laser beam 28 is a top hat type. Here, a beam homogenizer was installed in the optical path 20b through which the laser beam in the welding laser head 20 passes, and a top hat type laser beam 28 was obtained.

  In the cross section of the laser beam, the energy of the laser beam 28 is accumulated outward from the center of the cross section as the center O, and the minimum energy is obtained in the region 61 inside the boundary 60 which is 87% of the total energy of the laser beam 28 in the cross section. The value was 90% of the maximum value of energy. The boundary 60 and the maximum and minimum values of energy were determined by the method described above. In this laser beam 28, the diameter of the boundary 60 was 5 mm.

  Overlay welding of a single layer was performed along the outer periphery of the build-up surface 41 with a laser output of 2100 W, a welding speed of 300 mm / min, and a feeding rate of the filler powder 23 of 9 g / min.

  Then, the weld crack of the build-up part 50 was evaluated by the fluorescence penetration flaw detection test. Here, on the surface of the built-up portion 50, the powder 23 melted only on the surface adheres. Therefore, the surface of the built-up part 50 is uneven by the powder 23 to which a part is attached. When the fluorescent penetrant testing is performed in this state, the fluorescent penetrating flaw detection liquid penetrates into the irregularities on the surface of the built-up portion 50 and oozes out. Therefore, it is difficult to determine the defect. Therefore, the surface was ground with a grinder to remove the irregularities, and then a fluorescence penetration test was conducted.

  In the fluorescence penetration flaw detection test, the length of the weld crack on the entire surface of the built-up portion 50 was measured using a measurement microscope. FIG. 6 is a diagram schematically showing a side surface of the built-up portion 50 in order to explain the length of the weld crack on the entire surface of the built-up portion 50. As shown in FIG. 6, for example, it is assumed that weld cracks 70, 71, and 72 are generated at three locations on the entire surface of the built-up portion 50. The lengths of the weld cracks 70, 71, 72 are amm, bmm, and cmm, respectively, as shown in FIG. In this case, the length of the weld crack on the entire surface of the built-up portion 50 is (a + b + c) mm. That is, the length of the weld crack on the entire surface of the built-up portion 50 is a value obtained by integrating the length of each weld crack.

  The length of the weld cracks 70, 71, 72 is the distance between one end and the other end of the weld cracks 70, 71, 72, that is, a straight line connecting one end and the other end of the weld cracks 70, 71, 72. Is the length of

  Table 2 shows the measurement results of the weld crack length of the entire surface of the built-up portion 50.

  As shown in Table 2, there was no weld crack in Example 1.

(Example 2)
The build-up object 40 used in Example 2 was the same as the build-up object 40 of Example 1. IN625 was used as a filler material. The average particle size (median diameter) of the filler powder 23 was 90 μm. In Table 1, the chemical composition of the material which comprises the build-up target object 40 and a filler material is shown.

  A semiconductor laser was used as the laser oscillator 29. A laser beam 28 having a substantially square cross section was used. Therefore, the shape of the laser spot was substantially square. The energy profile of the laser beam 28 is a top hat type. Here, a beam homogenizer was installed in the optical path 20b through which the laser beam in the welding laser head 20 passes, and a top hat type laser beam 28 was obtained.

  In the cross section of the laser beam, the energy of the laser beam 28 is accumulated outward from the center of the cross section as the center O, and the minimum energy is obtained in the region 61 inside the boundary 60 which is 87% of the total energy of the laser beam 28 in the cross section. The value was 90% of the maximum value of energy. The boundary 60 and the maximum and minimum values of energy were determined by the method described above. In this laser beam 28, the length of one side of the quadrangle inscribed by the circular boundary 60 was 5 mm.

  The laser output, the welding speed, and the supply speed of the filler powder 23 were the same as those in Example 1. A built-up portion 50 is formed along the outer periphery of the build-up surface 41, and a new built-up portion 50 is formed on the built-up portion 50 in a state where the temperature (surface temperature) of the built-up portion 50 is 500 ° C. Formed. That is, the built-up part 50 laminated in two stages was formed. In addition, the temperature (surface temperature) of the build-up part 50 was measured with the radiation thermometer (hereinafter the same).

  In the same manner as in Example 1, the surface of the built-up portion 50 was ground with a grinder to remove the irregularities, and then a fluorescence penetration test was performed. Table 2 shows the measurement results of the weld crack length of the entire surface of the built-up portion 50. As shown in Table 2, there were no weld cracks in Example 2.

(Example 3)
The build-up object 40 used in Example 3 was the same as the build-up object 40 of Example 1. HA230 was used as a filler material. The average particle size (median diameter) of the filler powder 23 was 90 μm. In Table 1, the chemical composition of the material which comprises the build-up target object 40 and a filler material is shown.

  The laser oscillator 29, the shape of the cross section of the laser beam, the energy profile of the laser beam 28, the laser output, the welding speed, and the feeding speed of the filler powder 23 were the same as those in the second embodiment.

  A built-up portion 50 is formed along the outer periphery of the build-up surface 41, and the built-up portion 50 is newly formed on the built-up portion 50 in a state where the temperature (surface temperature) of the built-up portion 50 is 410 ° C. Formed. That is, the built-up part 50 laminated in two stages was formed.

  In the same manner as in Example 1, the surface of the built-up portion 50 was ground with a grinder to remove the irregularities, and then a fluorescence penetration test was performed. Table 2 shows the measurement results of the weld crack length of the entire surface of the built-up portion 50. As shown in Table 2, there was no weld crack in Example 3.

Example 4
The build-up object 40 used in Example 4 used the block material of GTD-111 used as a material of the moving blade of a gas turbine. The size of the build-up object 40 was the same as that of Example 1. IN617 was used as a filler material. The average particle size (median diameter) of the filler powder 23 was 90 μm. In Table 1, the chemical composition of the material which comprises the build-up target object 40 and a filler material is shown.

  The laser oscillator 29, the shape of the cross section of the laser beam, the energy profile of the laser beam 28, the laser output, the welding speed, and the feeding speed of the filler powder 23 were the same as those in the second embodiment.

  A built-up portion 50 is formed along the outer periphery of the build-up surface 41, and a new built-up portion 50 is formed on the built-up portion 50 in a state where the temperature (surface temperature) of the built-up portion 50 is 415 ° C. Formed. That is, the built-up part 50 laminated in two stages was formed.

  In the same manner as in Example 1, the surface of the built-up portion 50 was ground with a grinder to remove the irregularities, and then a fluorescence penetration test was performed. Table 2 shows the measurement results of the weld crack length of the entire surface of the built-up portion 50. As shown in Table 2, there was no weld crack in Example 4.

(Comparative Example 1)
The build-up object 40 and filler material used in Comparative Example 1 were the same as those in Example 3. The average particle diameter (median diameter) of the filler powder 23 was also the same as that of Example 3.

  A semiconductor laser was used as the laser oscillator 29. A laser beam 28 having a circular laser beam cross section was used. Therefore, the shape of the laser spot was circular. The energy profile of the laser beam 28 is a Gaussian type.

  In the cross section of the laser beam, the energy of the laser beam 28 is accumulated outward from the center of the cross section as the center O, and the minimum energy is obtained in the region 61 inside the boundary 60 which is 87% of the total energy of the laser beam 28 in the cross section. The value was 10% or less of the maximum value of energy. The boundary 60 and the maximum and minimum values of energy were determined by the method described above. In this laser beam 28, the diameter of the boundary 60 was 5 mm.

  The laser output was 2100 W, the welding speed was 300 mm / min, and the feed rate of the filler powder 23 was 9 g / min. A built-up portion 50 is formed along the outer periphery of the build-up surface 41, and the built-up portion 50 is newly formed on the built-up portion 50 in a state where the temperature (surface temperature) of the built-up portion 50 is 410 ° C. Formed. That is, the built-up part 50 laminated in two stages was formed.

  In the same manner as in Example 1, the surface of the built-up portion 50 was ground with a grinder to remove the irregularities, and then a fluorescence penetration test was performed. Table 2 shows the measurement results of the weld crack length of the entire surface of the built-up portion 50. As shown in Table 2, in Comparative Example 1, there was a weld crack, and the length of the weld crack on the entire surface of the built-up portion 50 was 12.1 mm.

(Comparative Example 2)
The build-up object 40 and filler material used in Comparative Example 2 were the same as those in Example 1. The average particle diameter (median diameter) of the filler powder 23 was also the same as that in Example 1.

  The shape of the laser oscillator 29 and the cross section of the laser beam were the same as those in Example 1. Here, in Comparative Example 2, the energy profile of the laser beam 28 in a state close to that of the top hat type was formed. That is, in the cross section of the laser beam, the energy of the laser beam 28 is accumulated outward with the center O of the cross section as the center, and the energy in the region 61 inside the boundary 60 which is 87% of the total energy of the laser beam 28 in the cross section. The minimum value of was 70% of the maximum value of energy. The boundary 60 and the maximum and minimum values of energy were determined by the method described above. In this laser beam 28, the length of one side of the quadrangle inscribed by the circular boundary 60 was 5 mm.

  The laser output, the welding speed, and the feeding speed of the filler powder 23 were the same as those in Example 1, and single layer overlay welding was performed along the outer periphery of the overlay surface 41.

  In the same manner as in Example 1, the surface of the built-up portion 50 was ground with a grinder to remove the irregularities, and then a fluorescence penetration test was performed. Table 2 shows the measurement results of the weld crack length of the entire surface of the built-up portion 50. As shown in Table 2, in Comparative Example 2, there was a weld crack, and the length of the weld crack on the entire surface of the built-up portion 50 was 3.2 mm.

(Comparative Example 3)
The build-up object 40 and filler material used in Comparative Example 3 were the same as those in Example 2. The average particle diameter (median diameter) of the filler powder 23 was also the same as that in Example 2.

  The laser oscillator 29, the shape of the laser beam cross section, and the energy profile of the laser beam 28 were also the same as those in the second embodiment. The laser output, the welding speed, and the supply speed of the filler powder 23 were also the same as in Example 2. However, in Comparative Example 3, the built-up portion 50 is formed along the outer periphery of the build-up surface 41, and the temperature (surface temperature) of the built-up portion 50 is 50 ° C. on the built-up portion 50. A built-up portion 50 was newly formed. And the build-up part 50 laminated | stacked on 2 steps | paragraphs was formed.

  In the same manner as in Example 1, the surface of the built-up portion 50 was ground with a grinder to remove the irregularities, and then a fluorescence penetration test was performed. Table 2 shows the measurement results of the weld crack length of the entire surface of the built-up portion 50. As shown in Table 2, in Comparative Example 3, weld cracks existed, and the length of the weld cracks on the entire surface of the built-up portion 50 was 7.8 mm.

  According to the embodiment described above, it is possible to suppress weld cracks such as solidification cracks and liquefaction cracks when overlay welding is performed using a laser.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Laser cladding apparatus, 20 ... Welding laser head, 20a ... End face, 20b ... Optical path, 20c ... Powder path, 20d ... Gas path, 21 ... Optical fiber, 22 ... Powder supply apparatus, 23 ... Powder, 24 ... Powder supply 25, shield gas, 26 ... gas supply device, 27 ... gas supply tube, 28 ... laser beam, 29 ... laser oscillator, 30 ... energy profile converter, 40 ... build-up object, 41 ... overlay surface, 50: Overlaying part, 51 ... Molten pool, 60 ... Boundary, 61 ... Area.

Claims (7)

A laser beam emitted from a laser oscillator as a laser beam, and an optical path portion for irradiating a built-up object made of a Ni-base superalloy;
An energy profile conversion unit that is provided in the optical path unit and constitutes the laser beam having a top-hat type energy profile;
A laser build-up welding apparatus, comprising: a filler material supply unit that supplies powder of the filler material to a laser beam irradiation unit of the build-up object. In a cross section perpendicular to the irradiation direction of the laser beam having the top hat type energy profile,
The energy of the laser beam is accumulated outward from the center of the cross section, and the minimum value of the energy is the maximum value of the energy in the region inside the boundary that is 87% of the total energy of the laser beam in the cross section. 2. The laser overlay welding apparatus according to claim 1, wherein the laser overlay welding apparatus is 80% or more.   3. The laser overlay welding apparatus according to claim 1, wherein the filler material is a solid solution strengthened Ni-base superalloy.   The laser overlay welding apparatus according to any one of claims 1 to 3, wherein a cross-sectional shape of the laser beam perpendicular to the irradiation direction is substantially rectangular.   The laser overlay welding apparatus according to any one of claims 1 to 4, further comprising a shield gas supply unit that supplies a shield gas toward the overlay surface. A build-up process in which a filler material is supplied to a build-up surface made of a Ni-base superalloy, and a laser beam is irradiated to form a build-up portion on the build-up surface with the melted melt material. Have
A laser overlay welding method, wherein an energy profile of the laser beam is a top hat type.   The laser build-up according to claim 6, wherein, in the build-up step, a new build-up part is laminated on the build-up part in a state where the temperature of the formed build-up part is 400 ° C. or higher. Prime welding method.

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